AAIB Bulletin 7/2017

AAIB Bulletin 7/2017
AAIB Bulletin
7/2017
TO REPORT AN ACCIDENT OR INCIDENT
PLEASE CALL OUR 24 HOUR REPORTING LINE
01252 512299
Air Accidents Investigation Branch
Farnborough House
Berkshire Copse Road
Aldershot
Hants GU11 2HH
AAIB Bulletin: 7/2017
GLOSSARY OF ABBREVIATIONS
aal
Tel: 01252 510300
Fax: 01252 376999
Press enquiries: 0207 944 3118/4292
http://www.aaib.gov.uk
AAIB investigations are conducted in accordance with
Annex 13 to the ICAO Convention on International Civil Aviation,
EU Regulation No 996/2010 and The Civil Aviation (Investigation of
Air Accidents and Incidents) Regulations 1996.
The sole objective of the investigation of an accident or incident under these
Regulations is the prevention of future accidents and incidents. It is not the
purpose of such an investigation to apportion blame or liability.
Accordingly, it is inappropriate that AAIB reports should be used to assign fault
or blame or determine liability, since neither the investigation nor the reporting
process has been undertaken for that purpose.
AAIB Bulletins and Reports are available on the Internet
http://www.aaib.gov.uk
This bulletin contains facts which have been determined up to the time of compilation.
Extracts may be published without specific permission providing that the source is duly acknowledged, the material is
reproduced accurately and it is not used in a derogatory manner or in a misleading context.
Published 13 July 2017
Cover picture courtesy of Stephen R Lynn
© Crown copyright 2017
Published by the Air Accidents Investigation Branch, Department for Transport
Printed in the UK on paper containing at least 75% recycled fibre
(www.srlynnphotography.co.uk)
ISSN 0309-4278
above airfield level
ACAS
Airborne Collision Avoidance System
ACARS
Automatic Communications And Reporting System
ADF
Automatic Direction Finding equipment
AFIS(O)
Aerodrome Flight Information Service (Officer)
agl
above ground level
AIC
Aeronautical Information Circular
amsl
above mean sea level
AOM
Aerodrome Operating Minima
APU
Auxiliary Power Unit
ASI
airspeed indicator
ATC(C)(O) Air Traffic Control (Centre)( Officer)
ATIS
Automatic Terminal Information System
ATPL
Airline Transport Pilot’s Licence
BMAA
British Microlight Aircraft Association
BGA
British Gliding Association
BBAC
British Balloon and Airship Club
BHPA
British Hang Gliding & Paragliding Association
CAA
Civil Aviation Authority
CAVOK
Ceiling And Visibility OK (for VFR flight)
CAS
calibrated airspeed
cc
cubic centimetres
CG
Centre of Gravity
cmcentimetre(s)
CPL Commercial Pilot’s Licence
°C,F,M,T
Celsius, Fahrenheit, magnetic, true
CVR Cockpit Voice Recorder
DME
Distance Measuring Equipment
EAS
equivalent airspeed
EASA
European Aviation Safety Agency
ECAM
Electronic Centralised Aircraft Monitoring
EGPWS
Enhanced GPWS
EGT
Exhaust Gas Temperature
EICAS
Engine Indication and Crew Alerting System
EPR
Engine Pressure Ratio
ETA
Estimated Time of Arrival
ETD
Estimated Time of Departure
FAA
Federal Aviation Administration (USA)
FDR Flight Data Recorder
FIR
Flight Information Region
FL
Flight Level
ftfeet
ft/min
feet per minute
g
acceleration due to Earth’s gravity
GPS
Global Positioning System
GPWS
Ground Proximity Warning System
hrs
hours (clock time as in 1200 hrs)
HP
high pressure
hPa
hectopascal (equivalent unit to mb)
IAS
indicated airspeed
IFR
Instrument Flight Rules
ILS
Instrument Landing System
IMC
Instrument Meteorological Conditions
IP
Intermediate Pressure
IR
Instrument Rating
ISA
International Standard Atmosphere
kgkilogram(s)
KCAS
knots calibrated airspeed
KIAS
knots indicated airspeed
KTAS
knots true airspeed
kmkilometre(s)
ktknot(s)
lbpound(s)
LP
low pressure
LAA
Light Aircraft Association
LDA
Landing Distance Available
LPC
Licence Proficiency Check
mmetre(s)
mbmillibar(s)
MDA
Minimum Descent Altitude
METAR
a timed aerodrome meteorological report
minminutes
mmmillimetre(s)
mph
miles per hour
MTWA
Maximum Total Weight Authorised
NNewtons
Main rotor rotation speed (rotorcraft)
NR
N g
Gas generator rotation speed (rotorcraft)
engine fan or LP compressor speed
N1
NDB
Non-Directional radio Beacon
nm
nautical mile(s)
NOTAM
Notice to Airmen
OAT
Outside Air Temperature
OPC
Operator Proficiency Check
PAPI
Precision Approach Path Indicator
PF
Pilot Flying
PIC
Pilot in Command
PNF
Pilot Not Flying
POH
Pilot’s Operating Handbook
PPL
Private Pilot’s Licence
psi
pounds per square inch
QFE
altimeter pressure setting to indicate height
above aerodrome
QNH
altimeter pressure setting to indicate
elevation amsl
RA
Resolution Advisory
RFFS
Rescue and Fire Fighting Service
rpm
revolutions per minute
RTFradiotelephony
RVR
Runway Visual Range
SAR
Search and Rescue
SB
Service Bulletin
SSR
Secondary Surveillance Radar
TA
Traffic Advisory
TAF
Terminal Aerodrome Forecast
TAS
true airspeed
TAWS
Terrain Awareness and Warning System
TCAS
Traffic Collision Avoidance System
TGT
Turbine Gas Temperature
TODA
Takeoff Distance Available
UHF
Ultra High Frequency
USG
US gallons
UTC
Co-ordinated Universal Time (GMT)
VVolt(s)
V1
Takeoff decision speed
V2
Takeoff safety speed
Rotation speed
VR
VREF
Reference airspeed (approach)
VNE
Never Exceed airspeed
VASI
Visual Approach Slope Indicator
VFR
Visual Flight Rules
VHF
Very High Frequency
VMC
Visual Meteorological Conditions
VOR
VHF Omnidirectional radio Range
AAIB Bulletin: 7/2017
CONTENTS
SPECIAL BULLETINS / INTERIM REPORTS
None
SUMMARIES OF AIRCRAFT ACCIDENT (‘FORMAL’) REPORTS
None
AAIB FIELD INVESTIGATIONS
COMMERCIAL AIR TRANSPORT
FIXED WING
Spitfire IXT
G-LFIX
15-Sep-16
3
HA-PPC
17-Jul-16
8
G-MYES
30-May-16
24
G-VINB
20-Jan-17
51
G-JLRW
G-AXFN
G-ETIV
22-Mar-17
06-May-17
07-Dec-16
55
57
58
G-TIVV
D-MNBU
17-May-17
25-Aug-16
65
66
ROTORCRAFT
None
GENERAL AVIATION
FIXED WING
None
ROTORCRAFT
Sud-Aviation SE-313B Alouette II
SPORT AVIATION / BALLOONS
Rans S6-ESD (Modified) Coyote II
AAIB CORRESPONDENCE INVESTIGATIONS
COMMERCIAL AIR TRANSPORT
Agusta AW139
GENERAL AVIATION
Beech 76 Duchess
Jodel D119
Robin DR400/180 Regent
SPORT AVIATION / BALLOONS
Aerotechnik EV-97 Eurostar
Ikarus C22
© Crown copyright 2017
i
AAIB Bulletin: 7/2017
CONTENTS Cont
MISCELLANEOUS
ADDENDA and CORRECTIONS
None
List of recent aircraft accident reports issued by the AAIB
(ALL TIMES IN THIS BULLETIN ARE UTC)
© Crown copyright 2017
ii
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AAIB Bulletin: 7/2017
AAIB Field Investigation Reports
A Field Investigation is an independent investigation in which
AAIB investigators collect, record and analyse evidence.
The process may include, attending the scene of the accident
or serious incident; interviewing witnesses;
reviewing documents, procedures and practices;
examining aircraft wreckage or components;
and analysing recorded data.
The investigation, which can take a number of months to complete,
will conclude with a published report.
© Crown copyright 2017
1
AAIB Bulletin: 7/2017
7/2017
G-LFIX
EW/G2016/09/14
ACCIDENT
Aircraft Type and Registration: Spitfire IXT, G-LFIX
No & Type of Engines: 1 Rolls-Royce Merlin 25 piston engine
Year of Manufacture: 1944 (Serial no: ML407)
Date & Time (UTC): 15 September 2016 at 1520 hrs
Location: Sywell Aerodrome, Northampton
Type of Flight: Commercial Operation
Persons on Board:
Crew - 1
Passengers - 1
Injuries:
Crew - None
Passengers - None
Nature of Damage:
Heavy damage to propeller, minor damage to
engine cowls, landing gear doors and wingtip
Commander’s Licence:
Airline Transport Pilot’s Licence
Commander’s Age:
60 years
Commander’s Flying Experience: 23,500 hours (of which 500 were on type)
Last 90 days - 150 hours
Last 28 days - 40 hours
Information Source:
AAIB Field Investigation
Synopsis
The left landing gear collapsed on the landing roll despite the pilot having selected the
landing gear down and confirmed indications that it was down and locked. The aircraft
subsequently left the runway and came to rest on grass beside it. The pilot and passenger
vacated the aircraft uninjured.
It was subsequently discovered that the left landing gear actuator seals had failed, preventing
the actuator from achieving full extension.
History of the flight
The pilot stated that he was conducting the second passenger flight in G-LFIX that day.
The weather was fine with a light wind favouring Runway 03L1. Having re-joined the circuit
downwind the pilot selected the landing gear down and felt both legs lower, then observed
the illuminated down lights indicating the landing gear was locked down. As there was a
bright sun the pilot briefly removed his sunglasses to check that indication was not in fact
glare on the indicator. A normal approach to Runway 03L was then flown.
The aircraft crossed the runway threshold at about 85 kt before landing in a 3-point attitude
with no bounce or yaw and initially tracked straight for about 250 m. However, at about
Footnote
1
Runway 03L is a concrete runway with a landing distance available of 1,000 m.
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AAIB Bulletin: 7/2017
7/2017
G-LFIX
EW/G2016/09/14
35 kt the left wing started to lower. The pilot tried to counteract this with full right aileron and
full rudder as the aircraft started to yaw rapidly to the left, departing the runway onto grass
beside it. The pilot switched the engine’s magneto switches off as the aircraft came to rest
on its nose (Figure 1). The aerodrome’s RFFS were quickly on the scene.
The pilot vacated the aircraft unassisted followed by the uninjured passenger with the use
of a ladder provided by the RFFS.
Figure 1
G-LFIX after the landing gear collapse
Landing gear description
The landing gear of the Spitfire Mk IX is operated by two hydraulic actuators, one for each
landing gear. In both the extended and retracted position each landing gear is held in
position by a spring-actuated chamfered locking pin which engages in either the down-lock
lug or the up-lock lug on each landing gear.
Extension of the landing gear requires the pilot to move the selector lever out of its detent.
This energises the hydraulic system and actuator, removing the load from the locking pin,
and rotates the locking pin 180o. Movement of the selector lever to the down detent retracts
the landing gear actuator, moving the landing gear past the chamfer of the landing gear
locking pin. While the landing gear is in motion down appears in the landing gear status
window on the landing gear selector. When each landing gear is fully extended the increase
in hydraulic system pressure operates a pressure switch which causes idle to be displayed
in the landing gear status window. In addition, when the landing gear locking pin has
engaged in the down-lock lug of the landing gear, the indication circuit for that landing gear
is completed.
© Crown copyright 2017
4
in the landing gear status window. In addition, when the landing gear locking pin has engaged
in the down-lock lug of the landing gear, the indication circuit for that landing gear is
completed.
AAIB Bulletin: 7/2017
7/2017
G-LFIX
Landing gear position indication
EW/G2016/09/14
Landing gear position indication
The Spitfire Mk IX is fitted with a landing gear position indicator on the left side of the
The Spitfire
IX indicator
is fitted with
a landing
gear
position
indicator on the
left sideWhen
of thethe
instrument
panel. Mk
The
consists
of two
black,
back-illuminated
panels.
instrument panel. The indicator consists of two black, back-illuminated panels. When the
bulbs behind the panels light up the word UP is displayed in the upper panel and the word
bulbs behind the panels light up the word up is displayed in the upper panel and the word
DOWN in
the lower panel, Figure 2.
down in the lower panel (Figure 2).
Indicator panel windows
Bulb positions (panel cover removed)
Figure 2
Landing gear indication panel
When both landing gear legs are locked in the down position and the respective indication
circuits are made, the down caption is illuminated. Two lights are fitted behind each caption
to provide indication in the event of a single bulb failure.
The landing gear indication system fitted to G-LFIX had been modified so that instead of
both bulbs behind the relevant caption illuminating only when both landing gear legs were in
the relevant position, the left bulb in each panel would indicate the position of the left landing
gear leg and the right bulb the position of the right landing gear leg. This meant that the
letters ‘D’ and ‘O’ of the word down in the panel would be illuminated by the left bulb and the
letters ‘W’ and ‘N’ would be illuminated by the right bulb.
The operator stated that the differences between this aircraft’s landing gear indicator and a
conventional indicator are verbally briefed to pilots during their conversion onto the aircraft
by the chief pilot.
Aircraft examination
After recovery of the aircraft by the maintenance organisation it was found that the left
landing gear was difficult to force into the down and locked position. The landing gear
selector was in the down position and the idle caption was showing in the landing gear
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AAIB Bulletin: 7/2017
7/2017
G-LFIX
EW/G2016/09/14
selector window. Further inspection revealed that the landing gear had failed to lock down
because the landing gear actuator ram chevron seals had failed and pieces liberated from
the seals had migrated between the actuator ram and the seal support plate, jamming the
actuator ram before it reached its full extension (see Figure 3).
Seal support plate
Seal Debris
Seals
Figure 3
Seal debris on landing gear actuator ram
Each landing gear actuator is fitted with three seals. In 2013, due to a hydraulic leak,
replacement seals were purchased and fitted by the maintenance organisation. As the
supplier only had four new seals available, two of the original seals were refitted to the
landing gear actuators. The maintenance organisation confirmed that the seals which failed
were from the four purchased in 2013. The seals have an estimated life of five years.
The manufacturer of the seals was advised of the event by the aircraft’s maintenance
organisation, which also contacted other Spitfire operators directly to ensure they were
aware of the problem. They discovered that other operators have had similar problems, but
that they had not informed the seal manufacturer.
All the seals were passed to the AAIB. Examination under high powered optical microscopy
confirmed that the failure of the seals had initiated in the region of the seal lip. The failure
surfaces indicated that the seal lip material had been drawn between the seal and the
actuator ram. Examination of the internal bore of the seals and the failure surfaces indicated
that the seal failure had been progressive, with small amounts of material being liberated.
The presence of this material between the seals and the hydraulic ram resulted in the
release of further material which, over a number of operating cycles, produced sufficient
material to jam the actuator ram within the seal pack.
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AAIB Bulletin: 7/2017
7/2017
G-LFIX
EW/G2016/09/14
Tests
Destructive and non-destructive testing was carried out on both the original and
replacement (2013) seals by two independent laboratories to identify a reason for the
failure of the 2013 seals. The tests did not identify a difference in either the physical
properties or the chemical constituents of the seals that could have made the 2013 seals
more prone to early failure.
During their investigation of the event the maintenance organisation carried out tests on the
landing gear position indication system. These confirmed that the indication system was
serviceable. They also showed that, in the event that the left bulb in the down indictor panel
did not illuminate, the indirect light produced by the bulb on the right side of the indicator
was sufficient to partially illuminate the letters D and O of the down indication.
Analysis
The partial collapse of the landing gear was caused by the failure of chevron seals in the
left landing gear actuator, which jammed the actuator before it reached the “down and
locked” position. When the actuator became jammed, the increase in pressure within the
hydraulic operated the pressure switch in the landing gear selector, which resulted in the
status indictor window changing from down to idle and provided an indication to the pilot that
the landing gear had completed its extension cycle. Extensive examination and material
testing was unable to identify a defect within the failed seals or a change in the chemical
composition of the seals purchased in 2013 that would have contributed to their failure.
No defects were found within the landing gear position indication system. The fact that the
left landing gear did not achieve a locked position meant that the left light bulb in the landing
gear position indicator would not have illuminated. However, tests showed that sufficient
light was produced by the right bulb to illuminate the D and O of the down caption.
Safety action
In order to prevent the illumination of the complete word “DOWN” in the landing
gear position indicator in the event that one landing gear has not achieved the
fully locked position, the maintenance organisation modified the landing gear
indicator to prevent light from either of the indicator bulbs illuminating the
complete down caption.
Conclusion
The collapse of the left landing gear was caused by a failure of the landing gear actuator
chevron seals, which jammed the actuator before the landing gear had reached the locked
position.
The reason for the failure of the chevron seals purchased in 2013 could not be determined.
The modification to the landing gear indicator panel should minimise the possibility of a pilot
being unaware of a failure of the landing gear to achieve a locked position.
© Crown copyright 2017
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AAIB Bulletin: 7/2017
HA-PPC
EW/C2016/07/04
ACCIDENT
Aircraft Type and Registration:
Sud-Aviation SE-313B Alouette II, HA-PPC
No & Type of Engines:
1 Turbomeca Artouste II C6 turboshaft engine
Year of Manufacture:
1960 (s/n 1500)
Date & Time (UTC):
17 July 2016 at 1700 hrs
Location:
Breighton Aerodrome, Yorkshire
Type of Flight:
Private
Persons on Board:
Crew - 1
Passengers - 4
Injuries:
Crew - 1 (Fatal)
Passengers - 4 (Serious)
Nature of Damage:
Aircraft destroyed
Commander’s Licence:
Private Pilot’s Licence (H)
Commander’s Age:
36 years
Commander’s Flying Experience: 708 hours (of which more than 164 were on type)
Last 90 days - 18 hours
Last 28 days - 8 hours
Information Source:
AAIB Field Investigation
Synopsis
The helicopter flew along the runway at about 30 ft agl and carried out a quick stop.
Witnesses reported a nose-up pitch attitude of around 45° was attained as the helicopter
flared, then, as it levelled, the rotor blades struck the tail boom. The helicopter rotated to
the right through 180° and dropped vertically to the ground. Everyone on board was taken
to hospital; the pilot died subsequently. No technical failure was found which could explain
the accident.
History of the flight
Previous flights
The pilot kept the helicopter at a private site located 27 nm to the east of Breighton Aerodrome.
On the day of the accident he flew it to Breighton, where a vintage aircraft fly-in event was taking
place. From there he flew several trips in the helicopter, taking friends and acquaintances for
short flights. At 1636 hrs, following a local flight with three male passengers, the helicopter
returned to Breighton. The pilot flew along Runway 28 and reduced speed above the runway,
before flying towards the parking area in a steep nose‑down attitude at a height of 30 ft to
50 ft. Approaching the fuel pumps the helicopter levelled and taxied forwards, however it
pitched nose-down momentarily a couple of times, bringing the tail boom into close proximity
to the rotor disc. It landed without incident in front of the fuel pumps; photographs taken from
outside the helicopter showed a steady nose-down pitch attitude of 3° in the hover and at
touchdown. The helicopter was refuelled with 112 litres of fuel.
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AAIB Bulletin: 7/2017
HA-PPC
EW/C2016/07/04
Accident flight
The passenger who subsequently occupied the left front seat of the helicopter for the
accident flight had flown an aircraft as part of a display formation earlier in the day. He
had just finished putting it away when he met the pilot outside the hangar. The pilot
offered him a flight in HA-PPC, which he accepted, and he went into the clubhouse to
advise his partner. He then went to the helicopter, where he discovered there was a
passenger who he knew seated in the back. Not knowing how much fuel was on board
he asked the pilot if it was still alright for him to join the flight and whether there was room
for anyone else. The pilot said it was fine and the passenger returned to the clubhouse to
see if anyone else wanted to come. One person agreed and then a second asked if they
could join as well. The passenger escorted them both out to the helicopter and checked
with the pilot to see if they could join the flight. The pilot accepted them and they boarded
in to the rear cabin.
The passenger who had invited the persons from the clubhouse, who was also a qualified
helicopter pilot and instructor on another type of helicopter, occupied the left front seat; dual
controls were fitted. Both front seat occupants wore full four-point harnesses. The other
three passengers were seated on the bench seat in the rear of the helicopter, which was
equipped with lap straps only. All persons on board were wearing headsets connected to
the intercom system. A pre-flight safety briefing was not given to the passengers.
At 1648 hrs, with five persons on board, the pilot started up, lifted to a hover, turned 30°
to the right and took off in a north-westerly direction. The helicopter was photographed
in a 3° nose-down attitude in the hover. During the climb, the pilot offered control to the
front seat passenger and a formal control handover took place. The passenger flew the
helicopter to the west and then around to the south, performing some general handling
manoeuvres at heights of between 1,000 ft and 2,000 ft amsl, before returning towards
the airfield. He then flew along the runway at a height of around 100 ft, whereupon the
pilot asked if he would like to do a zoom climb and a pushover at the end of the runway;
the passenger declined.
The pilot resumed control, again with a formal handover, and suggested the passenger
follow him through on the controls. He zoom-climbed to around 700 ft agl, pushed over into
a steep descent before levelling at 400 ft to 500 ft agl and turning into a left-hand circuit
pattern. He turned onto final approach at about 100 ft agl flew along the runway at a speed
of around 55 kt before carrying out a quick stop. The front seat passenger reported that the
quick stop was smooth and progressive with no perceptible yaw.
The onlookers described a nose-up pitch attitude of between 45° and 55° during the quick
stop. As the helicopter pitched nose-down towards a more level attitude there was an
audible “crack” and a “very loud bang”. One witness described seeing the tail lifting into the
rotor disc. The main rotor blades struck the tail boom and the engine exhaust cowling; the
tail rotor assembly separated from the helicopter. The helicopter rotated through 180° to the
right as it dropped vertically to the ground.
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AAIB Bulletin: 7/2017
HA-PPC
EW/C2016/07/04
Several bystanders ran across to assist. The helicopter was substantially upright but leaning
to the right. The engine had detached from its mounting and was lying on the ground a few
metres away; the sound of it spooling down could still be heard. Both doors had come open
in the accident sequence. The pilot unfastened his harness and fell sideways out of his side
door, his feet were trapped under the yaw pedals and he could not escape further without
assistance. The passenger in the right rear seat unfastened his lap strap and managed to
get himself clear of the helicopter before collapsing to the ground; the other occupants all
had to be assisted out of the wreckage. Emergency services attended the scene and the
five persons on board were transferred to hospital, either by road or by air ambulance. The
pilot died a few days later in hospital.
Accident site and wreckage
Actions by airfield staff
An immediate response was carried out by the airfield staff and emergency services followed
by methodical post-crash management action taken by the Chief Engineer at Breighton.
Shortly after the accident, the wreckage and detached items were moved away from the
main runway and covered to protect them from the elements. CCTV footage and witness
detail had been retained at the airfield and passed into AAIB custody. Figure 1 shows the
helicopter shortly after the accident on the airfield.
Figure 1
Helicopter wreckage
After an initial examination of the wreckage, the main rotor blades were removed and the
wreckage was transported to the AAIB HQ in Farnborough for a detailed examination.
© Crown copyright 2017
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AAIB Bulletin: 7/2017
HA-PPC
EW/C2016/07/04
Pilot information
The pilot’s full logbook records were not available for the investigation. He qualified initially
for a Private Pilot’s Licence (Helicopter) in 2002 with a Hughes 269 type rating, in July 2002
he added a SA341G, Gazelle, type rating and in 2007 an endorsement for a SA318/SE313,
Alouette. At the time of the accident the pilot held a valid EASA PPL(H) and a Hungarian
National PPL(H).
Following his purchase of HA-PPC in 2007 the aircraft logbooks recorded that 163:25 hours
had been flown on the helicopter. The pilot’s ‘on type’ experience is based on this data.
Recorded information
Recorded radar data for the period around the time of the accident was examined. Great
Dun Fell radar head, 72 nm to the north-west, showed primary returns, identified as
HA‑PPC, manoeuvring to the west and south of the airfield. The final contact was recorded
at 1656:22 hrs, 2 nm south-east of the airfield.
A rear-seat passenger took some pictures with his mobile phone during the flight and these
included several taken during the first low flypast but none closer to the time of the accident.
Video evidence was obtained from two security cameras mounted on a hangar to the south
of the runway which showed the helicopter manoeuvring on the previous flight and during
the accident flight. The cameras covered the east and west ends of the runway, but not the
centre portion where the accident occurred and therefore the accident sequence was not
recorded.
A spectator who had been photographing aircraft throughout the day took a number of
pictures of HA-PPC during the afternoon. He captured two sequential photographs, at
0.2 second intervals, showing disruption of the rotor head and main body of the helicopter,
while it was still airborne.
Aircraft description
The SE-313B Alouette II is a lightweight utility helicopter originally designed for a variety
of military and State roles. Examples of the type were used by armed forces including the
British Army and although a few remain in State usage, many are now owned and flown
privately.
HA-PPC first came into service in 1960 as XP967, operated by the British Army. It was
transferred to the UK civil register in 1990. The pilot purchased the helicopter in 2007 and
transferred it to the Hungarian register, although it continued to be based in the UK. He had
flown approximately 160 hours in HA-PPC.
The helicopter airframe is made up of a tubular steel frame through which all of the
major engine and transmission components can be seen. It has an enclosed cabin but
the majority of its panels, including the roof, are of clear Perspex giving the pilot and
passengers very good all round visibility. The helicopter can carry up to five people
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AAIB Bulletin: 7/2017
HA-PPC
EW/C2016/07/04
including the pilot and co‑pilot. The helicopter is powered by a Turbomeca Artouste II
single shaft gas turbine engine driving a three-blade main rotor and two-blade tail rotor via
a conventional transmission system. There is a centrifugal clutch and freewheel coupling
assembly between the engine and main rotor gearbox input. The tail rotor output shaft is
fitted with a hydraulic rotor brake consisting of disc and caliper assembly.
The cyclic and collective flying controls consist of a system of rods, levers and bell cranks
routed under the cabin floor and up behind the cabin to the fixed and rotating star assembly
attached to the main rotor gearbox. The lateral and longitudinal control systems are fitted
with servo units powered by a simple hydraulic system. Flying control servo assistance was
an optional extra in the Alouette series of helicopters. The system consists of a main rotor
gearbox-driven pump, reservoir and filters. Hydraulic pressure can be controlled by a pilot
operated servo on/off valve situated on the cabin floor alongside the co-pilot’s seat.
System pressure is displayed on a gauge on the side of the instrument binnacle. The Flight
Manual states that the hydraulic servo system requires the main rotor head to be fitted with
hydraulic blade dampers.
The tail rotor control is transmitted via the yaw pedals into cables and pulleys running along
the tail pylon into a pitch change actuation mechanism which operates through the tail rotor
gearbox.
The main rotor blades consist of an extruded aluminium alloy main spar which forms the
leading edge of the blade. The aerofoil section and trailing edge of the spar is constructed
of thin gauge aluminium alloy, packed with a synthetic resin foam filler to give rigidity to the
skin. Tip balance weights are fitted to the blades and covered by light alloy tip fairings. The
blades are attached to the rotor head blade sleeves by two tapered steel bolts. The main
rotor head is fitted with hydraulic piston drag dampers. In addition to the drag dampers,
there are cables attached between each blade at the outer end of the blade sleeve, held in
place by small articulated links. These cables are known as the blade spacing equaliser
system.
Tie bars are fitted within the blade sleeve which take the centripetal loads from the main
rotor blades onto the flapping hinge trunnion alleviating those loads from the blade sleeve
pitch change bearings.
Fuel is held in a single 580 litre (153 US gallon/464 kg) cubic tank within the helicopter
framework under the main rotor gearbox and supplied to the engine via an electrical booster
pump. Of the 580 litres of fuel, 15 litres (12 kg) is considered unusable and is shown by a
red marker on the fuel contents gauge scale. Low fuel is indicated by a red warning light
within the fuel gauge which illuminates when there is 60 litres (48 kg) remaining. It should
be noted that the fuel gauge is calibrated in US gallons and both metric and imperial weights
and quantities are used in the Flight Manual performance charts.
The Alouette series of helicopters are fitted with either skids, floats or wheeled landing gear.
HA-PPC was fitted with skids.
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The cockpit instruments are of a conventional electro-mechanical and pneumatic design.
HA-PPC was also fitted with a transponder and radio along with a Skyforce GPS. The
front seats and passenger bench seat in the rear, are of a lightweight tubular construction
with leather covered cushion facings on top of the original cord and canvas facings.
Flight Manual
The Operating Limitations section of the Flight Manual for the SE-313B Alouette II helicopter
includes, under the title ‘Manoeuvring limits’, the information:
‘The following recommendations should be observed:
- Over 3,000 lb (1,361 kg) gross weight, approach should be made at a
shallow angle
- Handle the aircraft gently near limit speed and reduce speed before
attempting sharp manoeuvres’
Weight and balance
The maximum all-up weight (MAUW) of the helicopter is 1,588 kg (3,500 lb) with a CG
range of 274 cm to 307 cm, measured from a datum forward of the aircraft nose. The
design and mechanical layout of the helicopter are such that fuel quantity is the balancing
factor when flights are being planned. If a pilot is planning to carry passengers they must
take into account that all persons and items in the cabin will bring the CG forward. The
addition of fuel will bring the CG aft.
Table 1 shows the last two weight and balance checks recorded for HA-PPC. Following the
most recent helicopter overhaul, there was in an increase in weight of 46 kg. It also shows
the basic CG moving forward from 320.5 cm to 317 cm. The reason for this is discussed
later in this report.
Date
Inclusions
Empty Weight
6 Aug 12
Fire extinguisher, first aid kit,
5x seat harnesses, 5x headsets,
Skyforce GPS, transponder,
unusable fuel
994 kg
(Note - does not include
fuel tank at red warning
level of 48 kg)
320.5 cm
1,088 kg
317 cm
Standard cockpit, 4x headsets,
first aid kit, battery, systems
10 Mar 16
filled with oils and fuel at red
warning level 48kg
Table 1
Weighing record details
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It was not possible to determine the precise quantity of fuel on board at the time of the
accident therefore a series of weight and balance calculations were completed (Table 2).
The fuel consumption at maximum weight and a cruise speed of 90 kt is approximately
175 litre/hr (140 kg/hr) and the VNE at sea level is 100 kt.
Fuel on
‘red’
warning
Fuel at takeoff assuming uplift
quantity of 90 kg
added to ‘red’ level in
the tank
Minimum possible fuel
remaining at the time of
the accident - assuming
previous shutdown fuel
above red warning level
Empty Weight
1,088 kg
1,088 kg
1,088 kg
Fuel
0 kg
90 kg
64 kg
Passengers & items
in the cabin
424 kg
424 kg
424 kg
Total
1,512 kg
1,602 kg
1,576 kg
CG
(Range 274-307 cm)
276.6 cm
278.2 cm
277.7 cm
Table 2
Weight and balance figures1
(Red font shows a total exceeding the maximum allowable 1,588 kg)
The CG position figures in the table shows the CG moving forward as fuel is used. The
range of its movement brings it close to but does not exceed the forward CG limit.
Aircraft examination
Aircraft structure
The helicopter had landed upright on its landing skids which had left deep indentations in
the surface of the grass runway. The landing skids cross bars and inclined shock absorbers
had bent, bringing cabin structure into close proximity with the ground. The cabin structure
was distorted, the doors had detached and the majority of the cabin Perspex transparency
had fragmented.
The structure supporting the main rotor gearbox had retained its basic shape over the fuel
tank but the gearbox itself had partially detached, tilted forward and leaning over to the left.
The tubular framework around and beneath the main rotor gearbox had suffered bending
and fractures to the various struts and ties. The fuel tank was distorted and had split
allowing the fuel to drain out on to the ground. The structures around the transmission
Footnote
1
The figures presented for the fuel load are based on the assumption that the pilot refuelled with 90 kg at the
point when the red fuel low warning light illuminated at 48 kg. It is possible that there was more than 48 kg
of fuel already in the tank, therefore the takeoff weight could have been more than 1,602 kg.
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deck were covered in a film of oil and spattered with grease. The oil had escaped from the
lubricating oil tank and its associated supply and return pipes which had been damaged
during the accident.
The tubular frame tail boom was in a highly disrupted state. All three tubes which make up
the triangular section of the framework had been distorted and severed approximately half
way up the tail boom. The tail rotor gearbox and associated framework had detached as
had the tail rotor protective skid. There was no evidence that the underside of the tail rotor
skid contacted the ground during the accident sequence. The stabiliser aerofoils and cross
tube were severely damaged and had also detached. The centre section of the cross tube
was heavily scuffed and flattened and the inboard face of the stabiliser was badly crushed
at its trailing edge.
Rotor head, blades and dampers
For identification during maintenance, the main rotor head, blades and associated
components are colour coded (red, blue and yellow) and marked with tape or painted
bands. All three main rotor blades had exhibited varying degrees of damage to their
aerofoil skin surfaces and their tip fairings had detached. The yellow blade had suffered
the worst damage and had lost the outermost upper section of aerofoil skin. One of the
pieces of skin material had a scuffed transfer of grey paint on to its outer surface. The
yellow blade main spar had taken on a permanent curved bend upwards and rearwards
along its entire length. The red and blue blade main spars were also damaged but not to
the same extent. The upper and lower skin surfaces of all three blades, from the blade
root outwards, showed evidence of multi-strand steel cable strikes. The hydraulic blade
damper trunnions had failed on all three blades. The yellow blade had undergone an
extreme lag or ‘retardation’ and the blue and red blades suffered an equally extreme lead
or ‘advance’ over-travel.
The blade spacing cables had detached between the red and yellow blades and between
the red and blue blades. In each case, the articulated links which connect the eye-end
to the cuff joint had broken across their attachment bolt hole. Laboratory analysis of the
broken cable links show that they all failed in overload.
The rotor head assembly had witness marks at various points on the articulated joints
(ie flapping and drag hinges) of all three arms and on the head boss due to over-travel
about the joints. The droop restrainer ring was in place and free to move within its location
slot but was compressed and misshapen in several areas around its circumference.
Cockpit controls and instruments
Despite severe distortion to the instrument binnacle, the helicopter instrumentation,
switches and controls were undamaged. The barometric altimeter was set at 1020 hPa
which matched the local QNH at the time of the accident. Apart from this setting no
meaningful data could be gathered from any of the other instruments which had decayed
to zero or null readings when electrical power was lost after the accident. The fuel shut‑off
cock, flow control lever and governor control lever were all in the forward max or open
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positions. The adjustable stop on the governor control lever quadrant was set forward of
the mid position.
Tail rotor
The two-blade tail rotor had lost the outer half of both of its blades but was still attached
by its hub to the tail rotor gearbox. The pitch change links were intact and responded to
a manual input to the pitch change actuation mechanism with full range and in the correct
sense.
Flying controls
The flying control rods and linkages from the cyclic and collective were bent and in many
cases broken behind the cabin leading up to the main rotor gearbox. Despite the damage
to these control runs, continuity and operation in the correct sense could be demonstrated
in the collective and cyclic control systems via the servos. The control rods mounted on
the main rotor gearbox between the bell crank pivot shaft and fixed star of the swash
plate assembly, through to the rotating star and into the red, yellow and blue pitch control
rods were relatively intact except for a slight bend. However, the lateral control rod had
fractured at the waisted portion above the eye-end adjustment thread. There was also
evidence of ferrous corrosion on the eye-end thread in the same area.
The yaw pedals were intact and free to move. The control rod between the yaw pedals
and control quadrant was distorted. The cables between the quadrant and the tail
rotor pitch change input helix on the tail rotor gearbox had broken near to the tail boom
structure disruption. However, continuity and operation in the correct sense could be
demonstrated.
The hydraulic system pipes had been damaged but the majority of other system
components were intact. There was fluid present in the system but there had been some
leakage from the damaged pipes. Although the servo selector valve hand wheel had
broken in two and was not attached to its valve, examination found the valve spindle to be
fully clockwise in its open servo on position.
Engine and transmission
The engine had fully detached and had come to rest next to the helicopter on the ground.
The output clutch assembly was free to rotate but the core of the engine was jammed.
The exhaust and its insulation cowl had also detached and there was crush damage to
the diffuser. There was also a perforation to the combustion chamber. Removal of the
diffuser released the tension on the rear bearing and the compressor and turbine assembly
became free to rotate. Despite the accident, the engine and its ancillary equipment were
in good condition. There was no evidence of foreign object debris within the engine.
Notwithstanding the detachment of the tail rotor gearbox and dislocation of the main rotor
gearbox, both assemblies were undamaged, free to rotate and contained lubricating oil.
The main rotor gearbox magnetic particle detection plug was free of debris. The tail rotor
drive shaft, inclined shaft (tubular tail rotor drive shaft which runs beneath the engine) and
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freewheel unit had detached from the helicopter. The inclined shaft head had been pulled
from its universal joint and the shaft which runs along the top of the tail boom had been
bent and showed evidence of a torque-twist failure at the outer end. The freewheel unit
worked correctly and was intact except for a small amount of distortion to its engagement
splines.
The photographs taken by chance during the accident sequence show the engine and
transmission shafts undergoing serious disruption and separation whilst the helicopter was
still airborne.
Crashworthiness
Although the design of this helicopter predates many of the crashworthiness requirements
of EASA Certification Specification 27, this helicopter absorbed most of the impact forces.
The skid cross tubes deformed uniformly and the seat frames and faces absorbed the
shock. The straps and harnesses retained the occupants and reduced the possibility of
them being ejected from the cabin during the accident. The fuel tank split in the impact but
did not burst open thereby reducing the possibility of fuel spillage as well as the likelihood
of a post-crash fire.
Meteorology
Meteorological data for Breighton is not recorded but reports from persons at the airfield
suggested that the weather was fine and clear with a west-south-west wind of 10 kt to 15 kt.
Photographs and video recordings taken at the time of the accident showed clear skies at
low level, with good visibility; the surface wind was gusty from a westerly direction.
Airfield information
Breighton is an unlicensed aerodrome situated at the south-west corner of a disused
military airfield. The field elevation is 20 ft amsl. The single grass runway, orientated
10/28, is 850 m in length and 45 m in width; all circuits are to the south. A parallel tarmac
taxiway is located on the south side of the runway, alongside which are various hangars
and buildings, including a clubhouse. A refuelling facility is positioned in front of the
clubhouse.
Organisational information
Overall condition and maintenance
Despite the damage to the helicopter the examination found it to be in good condition.
The Hungarian based Continued Airworthiness Management Organisation (CAMO) had
carried out a major overhaul of the helicopter and issued a Certificate of Airworthiness
and Release to Service on 11 March 2016. This included the helicopter check-weigh and
CG calculation. It was reported that during the major overhaul the cabin structure was
replaced due to an unacceptable level of degradation of the light alloy skin in the cabin
floor due to corrosion. The AAIB was informed that the replacement cabin was of German
origin and this is supported by the cabin specification plate fitted on the cabin floor.
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The Artouste C6 engine fitted to HA-PPC is recorded as having annual servicing and
although not recorded in its Engine Log Book, a Release to Service Certificate showed
that it had been overhauled in October 2005. It was due its next calendar based overhaul
in October 2020. The engine manufacturer has no record of this work being carried out
by any of their approved organisations.
Other information
Handling of flight controls
A non-qualified person on board an aircraft handling the flight controls for a short duration is
common practice but whether it is allowable under existing regulation is not clearly specified.
HA-PPC is an Annex II aircraft and is subject to national regulation in Hungary, not to EASA
regulation. The Hungarian Ministry of National Development advised that a passenger
cannot operate a helicopter without holding the appropriate type rating.
For EASA aircraft, Regulation (EC) No 216/2008, Article 7, states:
‘Except when under training, a person may only act as a pilot if he or she holds
a licence and a medical certificate appropriate to the operation to be performed.’
The EASA interpretation of the phrase ‘act as a pilot’ is equivalent to that defined by ICAO
where ‘to pilot’ is:
‘To manipulate the flight controls of an aircraft during flight time2.’
EASA states:
‘outside of a training context, a helicopter pilot without the required typerating, and travelling as a passenger, is prohibited from manipulating the flight
controls of the aircraft during flight time.’
In the UK the interpretation for an Annex II aircraft is similar to that for an EASA aircraft.
CAA Flight safety information publication3
CAA Safety Sense Leaflet 02 – ‘Care of Passengers’ states:
‘The Commander of an aircraft is responsible for the safety and well-being of his
passengers and the law requires a pre-flight safety briefing in any UK registered
aircraft.
This applies to ALL aircraft, including gliders, balloons, microlights and
helicopters, as well as ‘conventional’ aeroplanes.’
Footnote
2
3
P12 of Part 1 ‘Definitions’ in ICAO Doc 9713 ‘International Civil Aviation Vocabulary’.
Available at: http://publicapps.caa.co.uk/modalapplication.aspx?appid=11&mode=list&type=sercat&id=21
[Accessed 13 September 2016]
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Advice on the importance of the correct distribution of weight in a helicopter is provided in
the FAA ‘Helicopter Flying Manual, Chapter 06: Weight and Balance4. For forward CG it
states:
‘This condition is easily recognized when coming to a hover following a vertical
takeoff. The helicopter has a nose-low attitude, and excessive rearward
displacement of the cyclic control is needed to maintain a hover in a no-wind
condition. Do not continue flight in this condition, since a pilot could rapidly
lose rearward cyclic control as fuel is consumed.’
However this indicator can be disguised in strong wind conditions:
‘A forward CG is not as obvious when hovering into a strong wind, since less
rearward cyclic displacement is required than when hovering with no wind.
When determining whether a critical balance condition exists, it is essential to
consider the wind velocity and its relation to the rearward displacement of the
cyclic control.’
An illustration of the effect of the CG on pitch attitude is included and shown at Figure 2.
Figure 2
Illustration of the effect of CG on helicopter handling5
Analysis
The pilot had been inviting different people for flights during the course of the day. On this
occasion, although he hadn’t originally planned to, he accepted four passengers on board.
The helicopter, with these four passengers and an uplifted fuel load of 90 kg, exceeded the
Flight Manual limitation for maximum weight. The helicopter was also operating towards
the forward limit of its CG range.
Footnote
Available at: https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/helicopter_flying_
handbook/
5
Shown in: https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/helicopter_flying_
handbook/
4
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A safety briefing is a required part of every flight and gives the pilot an opportunity to advise
the passengers of features specific to the aircraft type and indicate the emergency escape
procedures. The absence of a briefing did not affect the outcome of this flight.
Weight and balance
In 2012 the helicopter empty weight was 994 kg including 12 kg (26.7 lb) unusable fuel,
ie an empty fuel tank. In 2016, after a major overhaul, the helicopter was reweighed and
recorded as having a weight of 1,088 kg. Taking into account this figure includes 48 kg
of fuel, the resultant empty weight was 1,040 kg. The revised empty weight was 46 kg
greater than the previous weighing record. This increase is likely to have been as a result
of the cabin change and explains the movement of the basic CG forward from 320.5 cm
to 317 cm. It is possible that the pilot overlooked these changes when he considered how
many passengers he could take on a flight.
For the accident flight, the weight of the helicopter with its fitted equipment, an assumed
minimum reserve (red light) fuel of 48 kg and just the pilot on board was calculated at
1,227 kg. The MAUW is 1,588 kg, thus the available payload for fuel and passengers
would be 361 kg. The pilot had loaded 90 kg of fuel, giving a maximum possible available
payload of 271 kg. The combined weight of the passengers and other non-essential
items on board was 285 kg, an exceedence of 14 kg or greater6. This degree of weight
exceedence was probably not significant for gentle flight manoeuvres but may have been
relevant for some more dynamic manoeuvres. The information provided in the Flight
Manual for operation at weights above 1,361 kg (3,000 lb) recommends a reduction in
speed before ‘attempting sharp manoeuvres’. During the accident flight a zoom climb
and a bunt were observed and on the previous flight the helicopter was flown towards the
parking area in a steep nose-down pitch attitude before levelling.
The Flight Manual weight of 1,361 kg (3,000 lb), above which the helicopter must be handled
‘gently’ at higher speeds and shallow approach angles are required, for HA-PPC represents
the pilot plus one hour of fuel on board with no passengers, or 30 minutes fuel with one
passenger.
Effect on handling characteristics
All weight in the helicopter cabin acts to move the CG forward whereas fuel moves the CG
aft. For the flight preceding the accident flight there were three male passengers on board,
and less fuel than on the accident flight. The CG is likely to have been towards the forward
edge of the range, leading to a nose-low attitude and rearward stick position in a zero wind
hover, a situation which brings the rotor disc closer to the tail boom. Cyclic control authority
is reduced, making it more difficult to reduce speed and decreasing manoeuvrability. The
CCTV recordings showed that at the end of this flight the rotor disc twice came close to
contacting the tail boom as the helicopter flew towards the fuel pumps.
Footnote
6
The figures presented for the fuel load are based on the assumption that the pilot refuelled with 90 kg of fuel
at the point when the red fuel low warning light illuminated at 48 kg. It is possible that there was more than
48 kg of fuel already in the tank, therefore the exceedence may have been greater than 14 kg.
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The helicopter was refuelled after this flight, moving the CG further aft. However, the
additional load in the cabin would have brought the CG forward. The observed nose-down
attitude in the hover suggests that the helicopter was operating with a forward CG which
would have brought the rotor disc closer to the tail boom in flight, increasing the possibility
of its contacting the tail boom.
Accident sequence
The helicopter component examination clearly shows that the main rotor disc came into
contact with the tail boom structure. It is evident from the damage to the main rotor blades
and their tips, along with the damage to the stabiliser and its cross tube, that the first impact
was from the yellow blade closely followed by blue and the red blades in succession. The
yellow blade tip missed the right stabiliser aerofoil but collided with the cross tube and
on into the inboard trailing edge corner of the left stabiliser aerofoil. Figure 3 shows the
damage to the stabiliser cross tube and path of the blade impact.
Figure 3
Damage to the stabiliser cross tube and path of the blade impact
This was the probable source of the “loud crack” described by the passengers and many
of the witnesses. The tip fairing was crushed and detached and its deformation precisely
matched the profile of the stabiliser trailing edge. In this initial impact, the cross tube was
flattened and there is evidence that the yellow blade, whilst in contact with the cross tube,
travelled underneath the tail rotor drive shaft and it is possible that it momentarily restricted
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its rotation to the extent that it twisted under torque and failed. It is also possible that
the torque-twist occurred when the shaft bent as the tail rotor gearbox and its associated
structure bent and separated from the tail boom. Photographic evidence shows a long
section of tail rotor drive shaft, still rotating, detached from the helicopter whilst it was
airborne and the torque-twist could only have happened prior to this event.
The tail structure suffered a number of main rotor blade strikes leading to complete loss
of structural integrity. With an NR7 at approximately 360 rpm, there could have been up to
18 blade passes and potential impacts per second.
With an Alouette II helicopter at rest, it can be shown that the most likely blade tip impact
point will be in the area where the stabiliser is fitted. However, it is very difficult to pull a main
rotor blade down to contact this area by hand against the anti-droop ring. Nevertheless,
in flight the aerodynamic and inertial forces have a large effect on the disc path and can,
under extreme circumstances, allow the tip of the main rotor to come into contact with the
tail structure. Potential blade impact may be exacerbated by a forward CG, which reduces
the distance between the blade tip path and tail boom.
The damage to the hydraulic dampers and blade spacing cables is likely to have occurred
at the first impact of the yellow blade leading to an inertial shock through the rotor head
when it momentarily slowed as the yellow blade transited through the structure. Then, as
this structure disintegrated, the head, which was still being driven, caused the red and blue
blades to accelerate under their own inertia to over-travel with enough energy to break
through the damper trunnions. The lead and lag of the damaged blades would then not
be damped or controlled; the effect would be for the blades to fly out of track leading to a
worsening out of phase situation between the blades. It is possible that it was during this
early sequence of events that the pitch rods were damaged.
It is also early in the sequence that the inter blade cables and drag dampers suffer significant
shock loading as the blades and head, still being driven from the main rotor gearbox,
collided with the tail structure. The two sequential photographs show the latter stages of
the sequence, by which time the disruption and deflection of the blades from their normal
track and phase was so great that one of the blades collided with the engine with such force
that it detached from the helicopter. This was probably the source of the “bang” described
by witnesses.
The tail rotor appears to have departed the helicopter and flown upwards and forwards,
suffering secondary damage after collision with the main rotor blades. This resulted in the
torque rotation of the helicopter through 180º as it dropped to the ground.
The sudden deceleration when the helicopter hit the ground resulted in all three main rotor
blades undergoing a violent droop whilst still rotating. The blades collided with the remains
of the tail boom structure severing the already damaged tubing to leave a distinctive angular
cut. It was also likely at this point that the droop restrainer ring was misshapen.
Footnote
7
NR – Abbreviation used to represent rotor rpm in rotary wing aviation.
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Finally whilst still in a drooped condition, a main rotor blade struck the cabin structure.
The impact caused severe distortion to the left side door frame, instrument binnacle and
fragmented the cockpit transparencies and brought the main rotor to a stop. Based on
the witness evidence and the helicopter’s proximity to the ground, it is estimated that this
whole sequence took less than five seconds.
Observations
It was suggested by outside observers that it was possible that the accident resulted from
the tail skid striking the ground. However, there is no evidence that the tail skid came into
contact with the ground prior to or during the accident.
The engine manufacturer could find no records that the overhaul had been carried out by
one of their approved organisations. However, the engine performance or condition was
not a causal or contributory factor.
Conclusion
The helicopter was well maintained, serviceable and in good condition prior to the accident.
All the damage to the helicopter’s structure, its components and systems is attributable
to the main rotor disc striking the tail boom structure in the vicinity of the stabiliser cross
tube. There was no evidence of pre-accident defects of the flying controls or transmission
system which could have led to the rotor disc colliding with the tail boom, therefore it
probably occurred as result of control inputs.
The helicopter was close to or above the MAUW of 1,588 kg (3,500 lb). Also, the CG was
towards the forward limit of the allowable range detailed in the Flight Manual, thus the
margin of clearance of the rotor disc from the tail boom in flight may have been reduced,
increasing the risk of the disc striking the tail boom.
It is probable that whilst a quick stop was carried out, coarse control inputs associated
with the dynamic manoeuver caused the main rotor disc to contact the tail boom.
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ACCIDENT
Aircraft Type and Registration: Rans S6-ESD (Modified) Coyote II, G-MYES
No & Type of Engines: 1 Jabiru 2200A piston engine
Year of Manufacture: 1992 (Serial no: PFA 204-12254)
Date & Time (UTC): 30 May 2016 at 1557 hrs
Location: Near Shifnal Airfield, Shropshire
Type of Flight: Private
Persons on Board:
Crew - 1
Passengers - 1
Injuries:
Crew - 1 (Fatal)
Passengers - 1 (Fatal)
Nature of Damage: Aircraft destroyed
Commander’s Licence: UK National Private Pilot’s Licence
Commander’s Age: 64 years
Commander’s Flying Experience: 185 hours (of which 8 were on type)
Last 90 days - 13 hours
Last 28 days - 10 hours
Information Source: AAIB Field Investigation
Synopsis
The aircraft was manoeuvring in the circuit at Shifnal Airfield, having flown there from
its base near Market Drayton. While appearing to reposition for an approach to land on
Runway 28, the aircraft was observed to stall and possibly enter a spin. It did not recover
before striking the ground in a field to the east of the airfield. The pilot and his passenger
were both fatally injured.
A review of records revealed that sixteen Rans S6 accidents, involving stalls and/or spins, have
been investigated in the UK by the AAIB since 1994. As a result, the Light Aircraft Association
(LAA) is conducting a review of accident data, on this and similar types of microlight, and a
flight test program, to determine factors that may have contributed to this accident history.
History of the flight
The aircraft was on a flight from its base at Longford, near Market Drayton, to Shifnal, a
grass airfield run by a flying club. The pilot/owner was in the left seat and a passenger was
in the right. After departure from Longford’s north-easterly runway, the aircraft flew around
the northern edge of Market Drayton and then turned south towards Shifnal Airfield. It
tracked down the west side of Shifnal Airfield, before turning and approaching the airfield’s
overhead from the south-west.
Club members at Shifnal reported that, because the wind was from the north, Runway 36
was in use, which visiting pilots would have been advised about when obtaining PPR (prior
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permission required) before arriving at the airfield. However, the landing ‘T’ in the signal
square indicated that Runway 28 was in use. Whether the pilot attempted to obtain prior
permission was not established but there was no record of him doing so. There was no
other traffic near Shifnal Airfield at the time of G-MYES’ arrival.
The aircraft turned on to the right hand downwind leg for Runway 28, from the crosswind
leg, and witnesses (club members) noticed that the aircraft was lower and closer to the
airfield than normal for that circuit. The aircraft appeared to be following the railway line
which runs just north of the airfield.
The club had a loudspeaker connected to a radio transceiver, tuned to the airfield frequency,
which was audible outside the club house. Two witnesses, who were outside, recalled
hearing a “downwind” report from G-MYES on the flying club’s radio and at the end of the
downwind leg the aircraft was observed turning right towards the final approach leg for
Runway 28. As the base turn continued, the aircraft flew through the Runway 28 extended
centreline. It then rolled wings level and headed towards the airfield, although noticeably
south of the normal final approach path and near one of the local noise-sensitive areas.
The aircraft then made a further turn onto an easterly heading but witnesses did not agree
on the direction of the turn. One witness described the turn as being “quite steep” and
at a low speed. During the turn, the aircraft was observed to roll abruptly, in a manner
suggesting a wing-drop stall, from which it recovered. Then, a little further from the airfield,
still on an easterly track and at low height, the aircraft banked left and appeared to enter
a spin, descending from the witnesses’ view. Realising that impact with the ground was
inevitable, the witnesses rapidly made their way towards the aircraft, while telephoning the
emergency services.
Another witness, not at the airfield, had a clear view of the field into which the aircraft
descended and saw the final part of the descent. He described the aircraft being pitched
nose-down, approximately 80°, and turning through at least 300°.
The wreckage was found in the field, with both occupants having sustained fatal injuries.
Meteorology
The Met Office provided an aftercast of conditions affecting Shifnal Airfield at the time of the
accident. Their summary stated:
‘Weather conditions at the location of the incident were generally benign, with
no significant weather or low cloud being reported in the vicinity. Winds were
north-easterly at around 10 KT, and visibilities were greater than 10 KM. There
was scattered fair weather cumulus and stratocumulus in the area, with the
occasional patch of more broken cloud. Cloud bases were no lower than
3000 feet. The general air temperature was between plus 18 °C and 19 °C,
with dew points of plus 9 °C to 11 °C. The weather conditions were consistent
with those forecast by the F215 chart and the Birmingham TAF.’
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The METAR at 1550 hrs for Birmingham Airport, 27 nm east-south-east of Shifnal, stated
that the wind was from 020° at 13 kt, and the automatic METAR for RAF Shawbury, 12 nm
north-west of Shifnal, stated that the wind was from 020° at 9 kt.
The pilot
The pilot, an experienced aircraft engineer, began learning to fly, on three-axis microlights,
in February 2012. He flew solo for the first time after 40 hours of dual training, of which
approximately 25 hours were in the circuit, and passed the skill test for issue of a National
Private Pilot’s Licence (NPPL), with the rating to fly microlights, in December 2013, after
accruing 76 hours. The pilot’s microlight rating was revalidated on 9 December 2015,
valid to 31 November 2017. At the time of the accident, he had accumulated a total of
185 flying hours, of which 132 were in command. His log book indicated that all his flying
was conducted in three-axis microlights.
The previous owner of G-MYES had demonstrated the aircraft to the pilot before they then
conducted a 30-minute flight together on 25 March 2016, with the previous owner occupying
the left seat and the pilot in the right seat. During that flight, the previous owner reminded
the pilot, who took control for parts of the flight, of the need to co-ordinate turns with rudder.
He also demonstrated a stall. In the circuit, on the base turn, he took control from the pilot
when he became concerned about the aircraft’s speed.
The pair conducted another 30-minute flight on 23 April 2016, after the pilot had purchased
the aircraft, with the pilot in the left seat and the previous owner in the right seat. This flight
included general handling, two stalls, one with flap up and one with full flap, and circuits. On
the first approach in the circuit, the previous owner became concerned that the speed was
too low and took control. There were two further landings, which were uneventful.
The pilot then flew the aircraft to his base near Market Drayton and began flying it regularly.
The pilot’s log book showed that he had undertaken 13 flights in G-MYES, including those
with the previous owner, totalling 7 hours and 45 mins of flying time on type. There was no
evidence he had flown any other Rans S6 aircraft.
The pilot had signed an appropriate medical declaration and was reportedly in good health.
Previous visits to Shifnal
The pilot’s log book showed that he had visited Shifnal on four previous occasions, in April
and September 2014 and January 2015. Historical wind information suggested that on
three of those flights, Runway 28 may have been in use. Since the flight in 2015, he had
flown to 20 other destinations from his base at Longford.
The passenger
The passenger was also a member of the flying club at Longford and flew a different type
of three-axis microlight. He and the pilot had flown as passengers in each other’s aircraft
previously. The passenger had not, according to available evidence, flown a Rans S6 as
pilot.
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Medical information
Post-mortem examinations were carried out on both the aircraft’s occupants by a pathologist,
who reported that there was no evidence of underlying disease in the pilot or the passenger
and that each had died from multiple injuries. Toxicology tests revealed no evidence of any
substance that could have contributed to the accident. It was also reported that, whilst no
evidence of incapacitation was found, the possibility could not be fully ruled out.
The pilot held a valid Medical Declaration.
Airfield information
The airfield at Shifnal is unlicensed and operated by a flying club, which welcomes visiting
aircraft. The airfield has a grass surface with two runways, orientated 10/28 and 18/36,
respectively. A windsock is positioned south-east of the intersection of the two runways and
a signal square had been laid out north of the Runway 28 threshold.
The flying club publishes instructions on its website, including maps and diagrams of circuit
procedures, as well as information that prior permission is ‘strictly’ required by visiting pilots.
The airfield is within the Shawbury Area of Intense Aerial Activity and the flying club is keen
to co-ordinate their activities with any military flying.
There are a number of noise-sensitive areas around the airfield, notably a small group of
buildings to the east, just south of the extended centreline for Runway 28.
The flying club website
One image on the flying club website shows the airfield, runways, and noise-sensitive areas,
together with the circuit patterns and two ‘gates’ through which aircraft should depart the
circuit (Figure 1).
The image shows two line features north of the airfield, a railway line and the A464 trunk
road (Priorslee Road). It also highlights an area to the north and east of the A464, which
is to be avoided, and indicates that the circuit should be flown parallel to, but south of, the
A464.
The flying club website also features an image of the airfield layout, with the railway line
shown to the north, without the circuit pattern being depicted (Figure 2).
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Figure 1
The website image of the circuit and noise-sensitive areas,
annotated ‘DO NOT OVERFLY!’
Figure 2
The website depiction of the airfield, showing the railway line to the north
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Information in a commercially published airfield guide
Similar information about the airfield was also available in a commercially published airfield
guide. When an AAIB investigator visited Longford, the day after the accident, a copy of this
guide was on the briefing table in the club caravan, open at the pages for Shifnal (Figure 3).
Figure 3
The information on Shifnal Airfield, and its noise and circuit procedures,
in the commercially published airfield guide
The ‘Noise and Circuit Procedures’ chart (Figure 4) in this guide showed one hachured line
north of the airfield, which the circuit parallels, but, although it followed the line of the A464
trunk road, the guide did not indicate whether it was a road, railway, or other line feature.
The guide also stated that the airfield is ‘strictly PPR’.
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Figure
4 4
Figure
The Noise and Circuit Procedures chart from the guide
In addition, the guide contained a warning about its content under the heading ‘Important’:
‘The [name of the flight guide] 2016 (the “Guide”) is a guide only and it is not
intended to be taken as an authoritative document. …. before flight, any
owner and user of the Guide should contact the operator of all departure and
destination airfield(s) to check that [sic] the extent to which any published
information set out in Aviation Publications and/or this Guide is still in force
and the extent to which it has been changed, supplemented, or amended. If
an owner’s or user’s departure or destination is an unlicensed airfield, such
a check with the operator must be undertaken before flight as any changes
relating to information concerning such an airfield may not be contained in
any Aviation Publication….’
Pilot’s notes and guidance
Pilot’s notes
The ‘LAA Type Acceptance Data Sheet TADS 204 Rans S6-ES’ states ‘A set of pilot’s notes
for the Rans S6-ES are included in the build manual’.
The UK agent for Rans aircraft informed the AAIB that all Rans S6 aircraft in the UK were
kit-built aircraft and that, historically, the manufacturer did not issue pilot’s notes with kit‑built
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aircraft, due to variations in build standard and different regulatory oversight regimes.
However, it did issue a set of pilot’s notes for factory-built aircraft in the USA.
Amongst the aircraft documents retrieved by investigators was a set of ‘Rans S6-ES Coyote
II Pilots notes’, which bore the manufacturer’s logo. The Rans agent did not recognise
this document, which appeared to have been written or modified by a Rans S6 pilot or
owner as some text was written in the first person. Further, the notes were relevant to a
Rotax‑engined Rans S6-ES, not one fitted with a Jabiru 2200A engine.
Guidance
Guidance and advice on the signs and symptoms of stalling and spinning and on stall
avoidance is provided in the CAA ‘Handling Sense Leaflet 2’, entitled ‘Stall/Spin Awareness’.
This leaflet is available from the CAA website1.
Recorded information
Sources of recorded information
Recorded information was available from a tablet computer2, portable GPS unit3,
smartphone4, Closed-Circuit Television (CCTV) recorded at Shifnal Airfield and
ground‑based primary5 radar (without altitude information) from Manchester Airport.
The tablet computer and portable GPS were owned by the pilot of the aircraft and the
smartphone by the passenger.
The smartphone contained a hand-held video recording, made by the passenger, as the
aircraft departed from Longford. The recording started shortly before the aircraft lined up for
takeoff on the north-easterly runway and ended just over three minutes later, as the aircraft
approached the town of Market Drayton, when it was at an altitude of about 1,000 ft amsl.
The ASI was in view and indicating zero when the aircraft was stationary on the ground.
However, once the aircraft started to move, the camera angle changed to a view outside
the cockpit. The pilot’s portable GPS unit was installed on the left side of the instrument
panel and his tablet computer in the lower centre of the instrument panel. The pilot, in the
left seat, was flying the aircraft throughout the period of the video.
The portable GPS unit was operating during the accident flight and had recorded
GPS‑derived position, altitude, track and ground speed at a nominal rate of once every
60 seconds. The first data point was recorded at 1536:13 hrs and the final data point at
1556:30 hrs.
Footnote
https://publicapps.caa.co.uk/docs/33/ga_srg_09webHSL02.pdf
Apple-manufactured iPad mini model A1550, operating an Airbox Aerospace Ltd Runway HD flight navigation
software application.
3
Airbox Aerospace Ltd-manufactured Aware 1. This device shoes the aircraft’s horizontal position on a
moving map display that includes topographical features, airports and waypoints as an aid to navigation.
4
Samsung manufactured Galaxy model SM-J500FN.
5
The aircraft transponder had not been selected by the pilot to transmit secondary radar Mode A (squawk
code) or Mode C (altitude) information.
1
2
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The tablet computer contained a flight plan6 for a direct route between Longford and Shifnal
Airfield, which is located just over 14 nm to the south-south-east (a track of 160°) from
Longford. No GPS track log was recorded for the accident flight on the tablet computer.
GPS track logs were available for previous flights from both the portable GPS unit and tablet
computer. None of these previous records contained flights to Shifnal.
The radar data commenced at 1537:27 hrs, shortly after the aircraft had taken off, and
ended at 1552:54 hrs.
The RTF frequency in use at Shifnal Airfield was not recorded.
Summary of recorded data
Figure 5 shows the GPS track of the flight from Longford to Shifnal and Figure 6 the final
two GPS points during the approach.
The radar and GPS tracks correlated closely, corroborating the relative accuracy of the two
independent data sources.
The aircraft took off at 1536 hrs from the north-easterly runway at Longford. The recording
on the smartphone of the takeoff and initial climb showed nothing unusual. Shortly
after, the aircraft made a right turn onto a southerly heading, whilst climbing initially to
about 1,700 ft amsl. As the aircraft approached the town of Donnington, it then climbed
progressively. At 1552 hrs, on a southerly track, the aircraft passed just less than half a
mile to the west of Shifnal Airfield. During the next three minutes, the aircraft was recorded
operating in an area 0.5 nm to the south-west of Shifnal Airfield, during which it descended
from a peak recorded altitude of 1,967 ft amsl to 1,050 ft amsl (600 ft agl).
Shortly after, footage from the CCTV showed the aircraft joining the crosswind leg for the
(right hand) circuit to Runway 28 at Shifnal Airfield. It then turned on to the downwind leg,
before disappearing out of camera view. As the aircraft turned onto the downwind leg, it
was recorded by the GPS as being at an altitude of 990 ft amsl (585 ft agl). The CCTV
corroborated witness accounts that the aircraft had turned to fly approximately overhead the
adjacent railway track.
At 1556:30 hrs, the last GPS data point was recorded. This indicated that the aircraft was
at an altitude of 628 ft amsl (290 ft agl), on a track of 148°M, with a groundspeed of 56 mph
(an estimated indicated airspeed of 51 mph (44 KIAS) based on the METAR for Shawbury).
The aircraft was 670 m from the threshold of Runway 28 and 300 m from the accident site.
Analysis of the tablet computer indicated that the aircraft struck the ground shortly after, at
about 1557 hrs.
Footnote
6
A GPS flight plan consists of sequentially ordered waypoints to assist in lateral navigation. A typical flight
plan consists of the departure and destination airport, with intermediate waypoints such as radio navigation
beacons or topographical features, if required. If a flight plan is selected, the GPS displays a track line on
the moving map display that the pilot can follow.
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Figure 5
GPS track of flight from Longford
Figure 6
Final GPS points during approach to Shifnal
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Description of the aircraft
The Rans S6 is a high-wing, strut-braced microlight aircraft with two side-by-side seats.
The airframe is mainly of bolted and riveted aluminium tube construction, with the forward
fuselage structure consisting of a welded tubular steel cage. The entire airframe is covered
with pre-sewn polyester fabric envelopes.
G-MYES, constructed from a kit in 1992, was originally built as a Rans S6-ESD variant.
However, the aircraft’s records indicated that in 2001 it was reconfigured to increase the
performance and raise the maximum gross weight from 386 kg to 450 kg. The aircraft
variant was subsequently designated as a Rans S6-ESD (Modified) Coyote II and was
considered structurally and aerodynamically equivalent to the Rans S6-ES variant. The
aircraft had completed approximately 2,144 flight hours since it was built.
It was fitted with a Jabiru 2200A four-stroke engine7 driving a two-bladed wooden propeller.
The engine was constructed in 2000 and had achieved approximately 1,203 operating hours.
The records indicated that the engine had previously experienced a number of stoppages
and power loss events; the most recent of these occurred in August 2008. Following this
event the fuel filter was cleaned and no further problems were experienced.
The LAA Permit-to-Fly was valid until 9 August 2016.
On-site examination
The aircraft had crashed in a gently sloping barley field approximately 683 m south-east
of the Runway 28 threshold at Shifnal, in an upright but steep nose-down attitude with an
impact heading of approximately 225o.
The engine and nosewheel had made indentations in the ground, although the main landing
gear had not made contact, indicating an approximate 70° to 80º nose-down attitude. An
area of undisturbed crop between the initial impact mark and the wreckage, indicated that
the aircraft had bounced approximately 5 m forward and to the left of the initial impact point,
before coming to rest. There were no other ground marks. However, the right wing had
flattened the crop at the initial impact point, indicating that the aircraft was in a right‑wing‑low
attitude at impact. The impression made by the right wing in the crop was parallel to and
approximately 5 m from the wing’s final position. This, together with the absence of any
evidence of rotational marks on the ground or in the crop, indicated that the aircraft was not
spinning at impact.
One propeller blade had broken off in the impact and fragmented into multiple pieces, almost
all of which were found at the initial impact point. The other blade remained attached and
intact. Neither blade displayed substantial evidence of leading edge damage nor chord‑wise
scuffing. This, together with the concentrated distribution of fragments of the damaged
blade, was indicative of a lack of propeller rotation, or rotation at low power, at impact.
Footnote
7
A number of power plants are available for this type of aircraft. G-MYES was originally equipped with a
Rotax 503 engine when it was first built, however it was modified with a Jabiru 2200A engine in 2001 at the
same time the aircraft was configured from an –ESD to –ES variant.
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The front of the aircraft, including the engine compartment, windscreen and cabin roof
area had sustained severe damage in the impact. The fuselage aft of the cockpit and the
empennage had remained relatively intact, although many of the tubular structural members
were broken. The wings were largely undamaged but the wing lift struts on both sides were
damaged.
The aircraft was equipped with a single polythene fuel tank, with an approximate capacity
of 40 litres, located in the rear fuselage behind the seats. It was noted that the fuel selector
was in the on position. Approximately 37 litres (28 kg) of motor gasoline was drained from
the fuel tank.
Following on-site inspection, the wreckage was recovered to the AAIB’s facility at
Farnborough for a detailed examination.
Detailed examination of the wreckage
Airframe
The examination confirmed that the operating system for the primary flying controls was
intact prior to the accident, although substantial disruption occurred during the impact.
It was not possible to ascertain the trim state of the aircraft due to disruption of the elevator
control and bungee trim system. The aircraft was fitted with a fixed metal trim tab on the
left elevator, a rudimentary aluminium plate, which was bent down approximately 90o to the
elevator surface; this appeared to be an excessive angle. The position of the trim tab was
not considered to be related to impact loads, as the aircraft tail did not contact the ground
during the impact. The previous owner could not recall the approximate angle at which the
trim tab had been set, and had never adjusted it, but did not believe it had been as much
as 90o.
Airspeed indication
The aircraft was not equipped with a stall warning system. The pitot probe, which
projected from the left wing leading edge was broken during the impact. The plastic tubing
connecting the pitot tube to the ASI was free from obstruction, however its integrity had
been compromised in two places. One area of damage was in the region where the tube
routed through cockpit structure, which had sustained significant damage during the impact.
The appearance of the damage indicated that it had been pierced by something sharp, and
the damage was considered to be impact-related. The second area of damage was a tear
immediately adjacent to where the tube expanded over the metal port on the back of the
ASI. The damage was examined visually and microscopically. Gouges and scoring on the
external surface, together with the direction of the tear suggested that this damage was
also most likely impact-related. Had this damage existed pre-impact, the size of the hole
resulting from the tear would have caused a substantial leak of pitot pressure to the ASI,
causing a large under-read and possible fluctuation of the needle.
The plastic hose was removed and the ASI was tested by applying air pressure. The needle
responded correctly across the relevant speed range, however a leak of air pressure from
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the unit was observed. The ASI case was intact but it is possible the leak was a result
of damage to the internal mechanism. Had the instrument leak been present before the
accident it may have manifested itself as an under-read; that is, the ASI may have displayed
a speed lower than the actual airspeed of the aircraft.
Flaps
The flaps are operated by a ‘handbrake’-style lever, located between the seats, which
is connected to a series of Teleflex cables running to the flap surfaces. The flap lever
is mounted between two metal plates, into which are machined four detents. The
selected flap position is maintained by a spring-loaded retractable lock-bar, operated by
a push‑button release on the end of the lever, which engages in the detents. The first
detent corresponds to the fully retracted position (flap lever fully down) and the remaining
three detents correspond to 11°, 20° and 43° of flap extension respectively. The geometry
of the detents is such that it prevents the flap lever from being lowered unless the release
button is pressed, but allows the lock-bar to ride up out of its detent and snap into the next
detent when the lever is raised. Therefore, the post-impact position of the lever alone
may not be a reliable indication of the flap setting prior to impact, due to the potential for
it to be driven upwards by impact forces.
The flap operating system was intact, except for bending deformation on the right hand
metal plate of the mechanism, indicative of a lateral impact. The flap lever was aligned with
the second detent but the retractable lock-bar wasn’t properly seated in the detent. Impact
deformation of the fuselage structure below and immediately forward of the flap lever
suggested that parts of the control stick torque tube and seat structure could have been
driven upwards during the impact, moving the flap lever, before relaxing back to a position
clear of the lever. However, closer examination of the flap lever mechanism revealed a
witness mark on the second detent, consistent with the shape of the retractable lock-bar,
suggesting the flap lever was in the second detent (ie one stage of flap (11o) selected) at
the time of impact.
Engine controls and indications
The engine rpm indicator was intact and the needle indicated approximately 1,250 rpm.
The choke lever was fully in. The right magneto switch was in the on position but disruption
to the left magneto switch meant it was not possible to determine its pre-impact position.
The carburettor heat control was partly dislodged from the instrument panel and it was
not possible to ascertain whether carburettor heat had been applied at the time of impact.
The throttle cable is actuated by the throttle lever, which is mounted at floor level
immediately forward of the seats. This area of the cockpit sustained substantial disruption
and it was not possible to ascertain any useful information from the throttle lever position.
Engine
The engine was subjected to a strip-inspection at a Jabiru overhaul facility. The
examination also included ancillary components, such as the mechanical fuel pump, oil
pump, carburettor and the ignition system.
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Disassembly of the engine revealed that it had not been subject to overhaul since installation.
The crank case and crank shaft were in good condition. However, cylinder compression
checks showed that cylinders No 1 and 3 had poor compression ratios, with some leakage
from the exhaust and inlet valves. Minor cracks were found on the cylinder heads of
cylinders No 1 and 2. The Jabiru specialist considered that the engine would run with these
defects but that they did not reflect a good state of repair. The oil was drained from the
engine; it was black and dirty and did not have the appearance of oil that had recently been
changed. The spark plugs appeared to be new, clean and with an appropriate firing gap.
The throttle cable terminated in a solid linkage which was mounted on a bracket attached to
the carburettor. The throttle cable exhibited a 90o bend, caused by impact loads (Figure 7),
and the mounting bracket was deformed. In order to confirm the pre-impact position of the
throttle valve, the throttle linkage was detached from the mounting bracket and the bracket
was straightened. When the throttle linkage was re-mounted on the bracket, its position
corresponded to the butterfly valve being fully closed. This indicated that the throttle was
closed at impact.
Throttle valve
(not visible)
Mounting
bracket
Throttle valve
actuation
Throttle cable
(note 90o bend)
Figure 7
The carburettor
Examination of the carburettor confirmed that the choke was in the off position. There was
a small amount of fuel in the carburettor fuel bowl and some small particles of debris. Some
corrosion was evident on the main jet holder and, when examined under a microscope,
solidified oily residue was evident on the internal bore. However, the main needle jet itself
was clean and free from debris. The idle jet also exhibited some oily residue; this is not
uncommon as oil can seep into the carburettor when the engine is shut down. The rubber
of the inlet manifold and fuel inlet hoses had lost all its flexibility, consistent with age-related
degradation.
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Carburettor icing
The CAA ‘Safety Sense leaflet 14’, on ‘Piston Engine Icing8’, describes carburettor icing and
its effect on engine performance as follows:
‘…carburettor (carb) icing [is] caused by a combination of the sudden temperature
drop due to fuel vaporisation and pressure reduction as the mixture passes
through the carburettor venturi and past the throttle valve.
If the temperature drop brings the air below its dew point, condensation results,
and if the drop brings the mixture temperature below freezing, the condensed
water will form ice on the surfaces of the carburettor. This ice gradually blocks
the venturi, which upsets the fuel/air ratio causing a progressive, smooth loss of
power and slowly ‘strangles’ the engine.’
The leaflet incorporates a graph of temperature and dew point (Figure 8), depicting the
probability of carburettor icing at various power settings. In the reported conditions, the
graph shows that moderate icing could be expected at cruise power, and serious icing at
descent power.
Figure 8
CAA Chart showing probability of carburettor icing; the red lines show the approximate
values of temperature and dew point at the time of the accident
Footnote
8
http://publicapps.caa.co.uk/docs/33/20130121SSL14.pdf
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Weight and Balance
The Rans S6-ESD (Modified) has a Maximum Takeoff Weight (MTOW) of 450 kg and a
maximum empty weight of 268 kg. The last weight & balance report for G-MYES was
produced in June 2014 and listed the aircraft empty weight as 238.8 kg. This information,
together with the occupant, fuel and baggage weights was used to calculate the weight and
balance of the aircraft at the time of the accident. The weight and balance was determined
to be within the aircraft manufacturer’s limits.
Maintenance
The check flight for the last Permit-to-Fly Certificate of Validity renewal was performed on
7 August 2015 by an LAA Inspector. The flight test report noted the onset of buffet in a stall
as occurring at 36 mph (31 KIAS), with flaps up, and 32 mph (28 KIAS) with flaps down. The
minimum airspeed achieved was noted as being 38 and 36 mph, respectively (Figure 9).
There were no additional comments regarding the stall characteristics of the aircraft.
Figure 9
Extract from check flight report
The LAA Inspector who conducted the check flight explained that he had probably made an
error, and entered the figures for the ‘minimum speed achieved’ on the ‘natural buffet speed’
line and vice versa. If so, the onset of buffet in a stall occurred at 38 mph and 36 mph, with
the flaps up and flaps extended, respectively.
Since acquiring the aircraft in April 2016, the pilot had made numerous searches on the
internet (using his iPad) for information regarding the Jabiru 2200 engine. These included
searches on 23 and 24 May 2016 relating to ‘spark plug gaps’, ‘spark plug torque loading’,
‘starter motor’, ‘overhaul’, ‘fuel pump gasket’ and ‘fuel pump seal’. An entry in the aircraft
log book on 22 May 2016, relating to a 25 minute flight, stated: ‘Local flight to warm eng
[engine] oil for change’. The subsequent entry on 27 May 2016 stated: ‘G/run [Ground run]
for leak check satis [satisfactory]. Flight check post oil /plugs /filter cx9’ suggesting that the
pilot had replaced the engine oil, oil filter and spark plugs.
Footnote
9
The abbreviation ‘cx’ is often used in aircraft logbooks to mean ‘check’ but it can also mean ‘change’. As the
logbook entry for the previous flight indicated the pilot’s intention to change the oil, it is considered that in this
instance it means ‘change’.
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Previous events
A review of other Rans S6 (all variants) accidents investigated by the AAIB was carried out
during the investigation. Details of those which were considered to involve stalling and/or
spinning are as follows, in reverse chronological order:
Date
Registration
26/8/16
G-MYLD
5/7/15
G-CDVF
22/8/14
G-BYOU
28/8/13
G-MYSP
14/7/13
G-BYMV
24/8/12
G-MZCA
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Extract from
AAIB report
Location
Near Cobham, Following an engine
Kent
problem, ‘the aircraft
stalled into trees’.
Result
No injuries
Damage to
propeller, engine
mounting, cockpit
frame and wings
Shifnal Airfield, Following an engine
2 seriously
Shropshire
problem, the ‘aircraft lost injured
height and struck the
Aircraft
ground in a steep nose- substantially
down attitude’.
damaged
Mount Airey
‘Shortly after takeoff the 1 seriously
Airstrip, South engine stopped and the injured
Cave, East
aircraft stalled.’
Aircraft damaged
Yorkshire
beyond economic
repair
Redhill
‘[the aircraft] was
1 fatality
Aircraft destroyed
Aerodrome,
climbing away after a
Surrey
touch-and-go landing
when the aircraft’s
engine was heard to
falter. The aircraft
was seen to slow in a
climbing attitude before
stalling and entering a
vertical dive from which it
did not recover.’
Near Stoke
‘Witness evidence
2 fatalities
Golding
suggests that the aircraft Aircraft destroyed
Airfield,
entered a stall followed
Leicestershire by an incipient spin after
entering the circuit.’
Private airstrip ‘The aircraft became
Aircraft
13 nm southlow and slow on final
significantly
south-east of
approach to a grass
damaged
Norwich
airstrip. A go-around
was initiated but the
aircraft appeared to stall
and rolled to the right.’
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G-MYES
EW/C2016/05/01
Extract from
AAIB report
‘Following a ‘touchand-go’… the aircraft
appeared to stall.’
1 seriously
injured
Aircraft destroyed
‘The aircraft stalled and
crashed shortly after
becoming airborne.’
Aircraft
extensively
damaged
Weston Park
near Shifnal,
Shropshire
‘During a go-around,
the aircraft stalled and
crashed…’
G-CBAZ
Middlewich,
Cheshire
‘…the aircraft’s
behaviour after takeoff
indicated that it had…
suffered a stall…’
24/12/03
G-CCNH
6/5/00
G-MZDG
6/10/99
G-MYLA
Felixkirk, North ‘Shortly after takeoff, at
Yorkshire
less than 50 feet agl,
the aircraft developed
a left roll that the pilot
could not correct even
with the application of
full opposite aileron.’ See
note 1
Barton
‘The initial climb was
Aerodrome,
normal until at about
Manchester
200 feet agl when
the aircraft’s left wing
dropped, probably
due to turbulence. In
attempting to regain
full control, the
handling pilot, who was
inexperienced, stalled
the aircraft’
Monewden,
‘The aircraft wing
Suffolk
then stalled and it had
entered the initial phase
of auto-rotation when it
hit the ground’.
2 aircraft
occupants
suffered minor
injuries; a
member of
the public was
seriously injured
Aircraft
substantially
damaged
The pilot suffered
a minor injury
Aircraft
extensively
damaged
Both wings
and fuselage
damaged
Date
Registration
14/2/09
G-BZYL
10/5/08
G-MYBA
28/3/05
G-CCNB
25/3/05
© Crown copyright 2017
Location
Brimpton
airstrip near
Aldermaston,
Berkshire
Chilbolton,
Hampshire
41
Result
Landing gear
collapsed,
propeller
smashed, engine
shock-loaded
and cockpit
area structure
distorted
1 fatality
Aircraft destroyed
AAIB Bulletin: 7/2017
G-MYES
Date
Registration
Location
4/7/99
G-MWRK
Near
Easingwold,
Yorkshire
13/10/94
G-MWUN
Penrith,
Cumbria
Extract from
AAIB report
‘…the engine went
completely quiet as the
aircraft passed over the
farm buildings adjacent
to the house. It then
entered a right turn and
descended out of sight.
A few seconds later [the
witness] heard a “dull
thud”. She ran across
the farm yard and saw…
[the] aircraft in a nosedown attitude “with its tail
in the air’ See Note 2.
‘…the pilot considered
that all the symptoms
indicated that a stall was
occurring… the aircraft
… [the aircraft] hit the
ground at about 40° to
45°, with the engine and
the nosewheel taking the
full impact’.
EW/C2016/05/01
Result
1 seriously
injured
Aircraft destroyed
2 occupants
suffered minor
injuries
Aircraft destroyed
Note 1: This is symptomatic of a stall with a wing-drop
Note 2: This description is consistent with an accident resulting from a stall
In summary, including G-MYES, this represents sixteen accidents involving stalling and/
or spinning, resulting in six fatalities, six serious injuries and five minor injuries since 1999.
Since 1989, CAA data indicates that the size of the UK fleet of Rans S6 aircraft (all variants)
has been as follows:
Year
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
© Crown copyright 2017
Total registered at
31 DEC
1
8
19
37
61
70
80
96
108
121
Total hours flown by the fleet
during the year
0
246
423
866
2,249
4,517
2,977
3,683
4,208
3,988
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Year
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
G-MYES
Total registered at
31 DEC
137
147
157
163
171
184
185
187
187
191
187
185
180
176
173
166
163
EW/C2016/05/01
Total fleet hours
Total hours flown by the fleet
during the year
4,748
4,251
5,440
7,024
6,838
5,809
5,973
5,603
6,943
4,993
5,615
4,857
4,827
3,712
3,605
3,436
1,184
108,013
Mean fleet size
131 aircraft
At the time of writing, the UK fleet comprised 161 Rans S6 aircraft.
Analysis
Operations
The flight seemed to be routine and the aircraft was serviceable, with sufficient fuel. The
weather conditions were suitable, with the surface wind favouring a landing on Runway 36
at Shifnal Airfield.
The pilot was appropriately qualified and had accrued a total of 185 hours, of which 7 hours
and 45 minutes were logged as being on the Rans S-6, including 1 hour of flying with the
previous owner. During these flights, the previous owner had reportedly intervened twice,
when he became concerned about the airspeed on final approach, and had pointed out the
importance of the correct use of rudder during turns.
Information about the destination, Shifnal Airfield, was available to the pilot in the commercial
flight guide which was found open at the page for Shifnal in the club caravan at Longford
the day after the accident. The entry included the requirement for PPR, as did the Shifnal
flying club website. It is not known whether the pilot attempted to obtain prior permission
but there was no record of him doing so. If he had contacted the flying club at Shifnal, he
would have been advised that Runway 36 was in use.
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The pilot had visited Shifnal previously, possibly when Runway 28 was in use, but it was
not established how he had flown the circuit on those occasions. He had visited 20 other
airfields since his last visit to Shifnal.
In the absence of a PPR briefing, the pilot probably did not know that Runway 36 was in
use. The prevailing conditions, as indicated by the windsock, favoured Runway 36 but the
signal square indicated that Runway 28 was active. On arrival, the aircraft flew just west of
the airfield, on a southerly track, and entered the circuit through the south-west gate. This
route positioned the aircraft on the dead side of the Runway 28 circuit. As witnessed, the
aircraft then flew a downwind leg for Runway 28, closer to the runway than normal, and,
concurrently, the pilot made a ‘downwind’ radio transmission.
It is not known why the aircraft flew the downwind leg closer to the airfield than seemed
normal. The radio transmission, which the pilot made downwind, did not include any
mention of a problem. The pilot may have been following the railway line, instead of the
A464 road, as the line feature to use to remain south of the avoid area. This would explain
the proximity of the aircraft’s downwind track to the airfield and, consequently, the reason
for the aircraft’s low height.
At the conclusion of the base turn, the aircraft was displaced south of Runway 28’s extended
centreline, which might be expected given the northerly wind and the proximity of the
downwind leg to the airfield. The aircraft then broke off the approach, did not go around,
and turned on to an easterly track, away from the airfield, possibly to re-position for the final
approach to Runway 28.
Manoeuvring in the final approach area
The wing-drop observed by witnesses was indicative of flight at an angle of attack which
was close to the stall. An initial recovery appeared to have been achieved but, at a height
of approximately 290 ft agl, the aircraft seemed to enter a spin from which it did not recover.
There was some evidence, from the engineering investigation, to suggest that spin recovery
had been initiated, as there were no rotational marks on the ground or in the crop at the
accident site and the aircraft had struck the surface in a steep nose-down attitude.
Airfield information
The various charts for the airfield showed one or both of the two line features north of the
airfield; the railway line and the A464 trunk road. They were similarly orientated, running
east-south-east or south-east, and both are near the northern airfield boundary. In the
commercial flight guide, the hachured line which delineated the boundary of the downwind
leg was not annotated as a road or railway. However, the flying club website did show that
the A464 was the line feature to remain south of on the downwind leg.
The warning included in the commercial flight guide set out the limitations of the information
it included and reminded pilots, planning to land at unlicensed airfields, to contact the airfield
operator in advance.
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Medical information
The post-mortem examinations found no evidence of underlying disease and concluded
that the pilot and passenger had suffered fatal injuries. Toxicology tests also revealed no
evidence of any substance that could have contributed to the accident. While there was
no evidence that the accident was the result of some form of incapacitation, the possibility
could not be ruled out fully.
Pilot’s notes
The provenance of the pilot’s notes found with the aircraft documentation could not be
established. The LAA TADS 204 for the Rans S6-ES indicated that a set of pilot’s notes is
included in the original build manual for each aircraft. However, the UK Rans sales agent
commented that the manufacturer did not issue pilot’s notes with kit-built aircraft, due to
variations in the build standard and different regulatory oversight regimes, although it did
provide them with factory-built aircraft in the USA. In addition, the original build manual
may not always reflect the actual configuration of an aircraft, especially if the aircraft has
been modified or re-engined. The LAA has, therefore, committed to produce appropriate
pilot’s notes, as described in the ‘Safety Action’ section later in this report.
Engineering
It was not possible to make any assessment of spin direction from observation of the
aircraft wreckage and ground marks. However, it was established that the aircraft had
struck the surface in a steep nose-down attitude in a field about 700 m to the south-east
of Shifnal Airfield.
The investigation did not identify any pre-accident mechanical defects in the aircraft, or
its flight controls, which could have contributed to a departure from controlled flight. The
fixed‑trim tab on the elevator was observed to be bent down approximately 90o to the elevator
surface. The LAA commented that, had the aircraft flown with such an extreme deflection
on the trim tab, the effect would have been similar to that with a normally deflected tab but
that it would cause additional drag. It did not consider that the additional drag would have
had a significant effect on the aircraft handling or performance.
While the investigation identified a tear in the plastic tube of the pitot system and a pressure
leak in the ASI, such anomalies, had they existed before the accident, would probably
have resulted in the ASI significantly under-reading ie the aircraft’s speed would have been
greater than that indicated. This would have been evident to the pilot.
Examination of the engine, propeller and ground marks indicated that the engine was
operating with low, or no, power at the point of impact. In particular, it was determined that
the throttle was closed at the time of impact, although it was not possible to establish why.
The possibility of carburettor icing causing a reduction or loss of engine power could
not be dismissed. In the prevailing conditions, moderate carburettor icing could have
occurred at cruise power and serious carburettor icing at descent power. If carburettor
ice had built up during the descent and circuit, it could have caused a lack of power during
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the final manoeuvres. The transient nature of carburettor ice makes it difficult to identify
as a causal factor.
Alternatively, a reduction or loss of engine power may have occurred for some other,
undetermined, reason. A number of anomalies were noted with the engine during detailed
examination, which may have affected engine efficiency or performance. So, although
there were no conclusive findings from the engine examination, the possibility of an engine
stoppage or power loss, for reasons other than carburettor icing, could not be ruled out.
The oil drained from the engine did not have the appearance of oil that had recently been
changed, yet the logbook indicated that this procedure had been carried out by the pilot a
few days prior to the accident. Conversely, the spark plugs, which were recorded as being
changed at the same time, appeared new. A review of earlier logbook entries did not identify
any oil changes in the preceding few years. It is possible that previous owners were not in
the habit of recording engine oil changes in the logbook, or it may be that an oil change had
not been carried out for some time. If so, the fresh oil may have quickly become dirty by
mixing with the remains of the old oil in the engine.
Safety Action
As a result of the rate of stall/spin accidents involving Rans S6 aircraft in the UK,
the LAA has undertaken to conduct a safety review encompassing the following
aspects:
●● ‘Complete a review of accident data with the type to date, including
consideration of the aircraft configuration, weights and cg positions, mission
and pilot profiles of those involved, including a comparison with the accident
data for similar types of microlight
●● Carry out a flight test program on at least two representative examples,
to investigate possible handling, performance or other factors that might
contribute to an elevated accident rate, - including in particular:
© Crown copyright 2017
♦♦
Longitudinal stability
♦♦
Ability to trim (in pitch)
♦♦
Longitudinal and lateral/directional trim changes with changes in
power and configuration (ie flap position)
♦♦
Directional stability and control, including contributing effects of
adverse yaw with aileron input, and any contributing ergonomic
aspects
♦♦
Pre-stall warning
♦♦
Stall characteristics
♦♦
Ease of operation of controls
♦♦
Adequacy of low-speed stall recovery/climb performance at
different weights and centre of gravity positions
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EW/C2016/05/01
♦♦
Behaviour in a simulated engine failure
♦♦
Instrumentation - in particular adequacy of indication of airspeed
and slip’
The LAA has advised that the applicable paragraphs of BCAR Section S, both
current and extant at the time the type was introduced to the UK, are being
used as the basis for this evaluation. The results of the safety review will be
communicated to all Rans S6 pilots within the LAA membership
The LAA has also undertaken to produce a series of pilot’s notes for the Rans
S6, tailored to each airframe/engine combination on the UK fleet, on completion
of the flight tests. The relevant Rans S6 TADS will be updated accordingly.
Flying club
Recognising the possibility of future confusion, the flying club at Shifnal Airfield
reported that it had removed the landing T and signal square, to prevent incorrect
signals being displayed.
Conclusions
The aircraft appeared to be manoeuvring at low speed in the circuit at Shifnal Airfield,
having flown there from its base near Market Drayton. While apparently repositioning for
an approach to land on Runway 28, the active runway indicated by the signal square, the
aircraft was observed to stall and possibly enter a spin. It did not recover before striking the
surface in a steep nose-down attitude in a field to the south-east of the airfield. On impact,
the engine was operating at low, or no, power. Although there were no conclusive findings
from the engine examination, the possibility of an engine stoppage or power loss, due to
carburettor icing or other reasons, could not be ruled out.
Shifnal Airfield advises visiting pilots that prior permission is required (PPR) before arrival,
however, there was no evidence that the pilot had contacted the airfield. Had he done so,
he would have been advised that Runway 36 was in use.
The pilot had recently bought the aircraft and had accrued about 8 hours on the type, flying
this aircraft. It was reported that, during two flights on G-MYES with the previous owner,
he, the previous owner, had taken control from the pilot when he became concerned about
the aircraft’s speed.
The post-mortem examination found no evidence of underlying disease or substance that
could have contributed to the accident and concluded that the pilot and passenger had
suffered fatal injuries. While there was no evidence that the accident was the result of some
form of incapacitation, the possibility could not be ruled out.
A review of records revealed that sixteen Rans S6 accidents have been investigated in
the UK by the AAIB since 1994. As a result, the LAA is conducting a review of accident
data on the aircraft type, including a comparison with the accident data for similar types
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of microlight, and a flight test program to investigate factors that might contribute to this
aircraft’s accident rate. It has also committed to produce a series of pilot’s notes applicable
to Rans S6 aircraft of the various configurations existent in the UK.
Advice on the awareness of stalling and spinning in general aviation is provided in the
CAA’s ‘Handling Sense Leaflet 2’10, entitled ‘Stall/Spin Awareness’, which is available on
the CAA website.
Footnote
10
https://publicapps.caa.co.uk/docs/33/ga_srg_09webHSL02.pdf
© Crown copyright 2017
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AAIB Correspondence Reports
These are reports on accidents and incidents which
were not subject to a Field Investigation.
They are wholly, or largely, based on information
provided by the aircraft commander in an
Aircraft Accident Report Form (AARF)
and in some cases additional information
from other sources.
The accuracy of the information provided cannot be assured.
© Crown copyright 2017
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G-VINB
EW/G2017/01/09
INCIDENT
Aircraft Type and Registration: Agusta AW139, G-VINB
No & Type of Engines: 2 Pratt & Whitney Canada PT6C-67C turboshaft
engines
Year of Manufacture: 2012 (Serial no: 31398)
Date & Time (UTC): 20 January 2017 at 1627 hrs
Location: Ravenspurn North Platform, North Sea
Type of Flight: Commercial Air Transport (Passenger)
Persons on Board:
Crew - 2
Passengers - None
Injuries:
Crew - None
Passengers - N/A
Nature of Damage: None
Commander’s Licence: Airline Transport Pilot’s Licence
Commander’s Age: 43 years
Commander’s Flying Experience: 6,035 hours (of which 1,964 were on type)
Last 90 days - 99 hours
Last 28 days - 20 hours
Information Source: Aircraft Accident Report Form submitted by the
pilot
Synopsis
After reporting for duty, a change in the flying programme resulted in a requirement for
the crew to fly a seven-sector shuttle at short notice. Whilst the commander reviewed the
technical log and discussed some issues with the engineering department, the co-pilot
completed the flight planning. The initial plan was to refuel on West Sole Alpha platform
but the flight crew surmised that the seven sectors could be completed with round trip
fuel. While re-planning the flight, the fourth destination was incorrectly inserted as
Ravenspurn North platform rather than Ravenspurn Alpha platform. The error was not
noticed and the flight proceeded to land at Ravenspurn North platform, whose helideck
was not manned.
History of the flight
The flight crew reported for a base duty standby period at Norwich at 1155 hrs and
1200 hrs, respectively, expecting a 1630 hrs departure. However, freezing fog in the
morning had disrupted the flying programme. On arrival, the crew were informed they
were required for a departure as soon as possible for a seven-sector shuttle, including
refuelling and shutting down on West Sole Alpha platform. The crew then discussed
the route and completed the planning accordingly. Initially, no payload information was
available as the customer’s flight planning sheet had not yet arrived.
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When the customer’s flight planning sheet was issued, which detailed the payload, the
crew realised that the flight could be completed without refuelling offshore. As a result, the
co-pilot re-planned the seven sectors while the commander went to review the aircraft’s
technical log. While doing so, he was also asked to advise the engineering department on
a technical defect with another helicopter.
While re-planning, Ravenspurn Alpha was transposed to Ravenspurn North on the operator’s
fuel planning sheet for sector four. Once the commander returned to join the co-pilot, the
crew rebriefed. The routing was correct on the customer supplied flight planning sheet but
the error on the fuel planning sheet was not noticed.
The aircraft departed Norwich and the first three sectors were completed without incident.
The crew then carried out a rotors-running turnaround on West Sole Alpha platform, during
which they received radio calls regarding the payload on the final, seventh sector and the
manifests for the fourth and fifth sectors. Whilst the co-pilot was dealing with the payload
request, the commander programmed the FMS. The crew were also aware that another
helicopter was inbound, to land on the helideck.
On departing the West Sole Alpha platform, the helicopter proceeded to the Ravenspurn
field. The co-pilot made a radio call to request helideck availability from the Ravenspurn
Field Helicopter Landing Officer (HLO) but only used the word “Ravenspurn” when providing
the name of the platform on which the crew intended to land, instead of “Ravenspurn North”.
The HLO responded: “Ravenspurn Alpha deck is available, standing by on the north side”.
However, the crew did not pick up on the discrepancy between their intended destination
and the clearance and carried out an approach and landing to Ravenspurn North. There
was no helideck crew present, as required by the operator, and a radio call alerted the crew
to the fact they had landed on Ravenspurn North rather than Ravenspurn Alpha, where they
were expected (Figure 1).
Once the crew realised their mistake, they remained rotors running and requested a helideck
crew, in accordance with the procedure in the operator’s Operations Manual. Once the
helideck crew were in place, the helicopter departed for the Ravenspurn Alpha platform.
The remaining sectors were completed without incident.
Procedures
Fuel planning is completed on the operator’s AW139 flight planning software, which uses
a drop-down menu for the selection of each destination. The fuel plan is supplemented by
a flight planning sheet, which is supplied by the customer and lists the payload for each
sector. This is generated by a system called Vantage, which companies use across the
North Sea to generate payload information for operators.
The operator’s flight planning software and Vantage use codes rather than the full name
of platforms. However, the codes used by the operator’s flight planning software, and the
helicopter’s systems, differ from those used by Vantage. This complicates any crosschecking
of the flight plan, as a decode is required. On the operator’s and helicopter’s systems, the
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code used for Ravenspurn Alpha was RA but Vantage used RAVA. Similarly, Ravensprun
North was RVN versus RAVN.
The initial plan for the seven-sector task included a shutdown and refuelling on West Sole
Alpha, with the onward sectors detailed on a second flight plan. On this occasion, the
flight planning sheet, with the payload information, arrived after the first fuel plan had been
completed.
Once the crew had the payload information, they realised that they could complete the trip
without refuelling offshore. Re-planning involved re-ordering the destinations into one flight
plan, rather than the initial two. This involved the co-pilot selecting the destinations using
the drop down menu and it was during this process that the destination for sector four was
mis-selected as Ravenspurn North (RVN) rather than Ravenspurn Alpha (RA).
The remaining sectors were completed without incident.
Figure 1
©RigMap
Rig map of the Ravenspurn Field (Ravenspurn Alpha is denoted as RA)
Analysis
Once the crew received their tasking for the multi-sector day, they began flight planning.
They were hampered by a lack of onward payload information, which, when it did arrive,
meant they could complete all the sectors without the requirement to refuel offshore. This
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G-VINB
EW/G2017/01/09
resulted in rapid re-planning by the co-pilot, while the commander was otherwise occupied
checking the helicopter’s technical log and advising the engineering department about
another helicopter. This lessened the time the crew had together to check the new flight
plan, leading to the incorrect destination for the fourth sector not being identified. Contrary
to their expectation, there was also time pressure from the moment the crew reported for
duty, due to the weather which had disrupted operations that morning.
The flight crew abbreviated the name of the installation in R/T transmissions from
“Ravenspurn North” to “Ravenspurn”. As a result, neither the flight crew nor the HLO
identified that the helicopter was heading for Ravenspurn North, which had an unmanned
helideck, rather than Ravenspurn Alpha where they were expected. The HLO did use
“Ravenspurn Alpha” in his transmission on the helideck availability but the discrepancy was
not picked up, perhaps due to confirmation bias.
Conclusion
An error at the flight planning stage led the crew to land on an unmanned helideck.
There were a number of occasions when the error could have been picked up; briefing
before departure from Norwich, crosschecking the flight plan and payload information,
during the radio calls with the Ravenspurn HLO and in programming the FMC. These
opportunities were missed through perceived time pressure, differences in codes and
possibly confirmation bias in the crew.
Once the mistake was realised, the crew correctly followed the operator’s procedures,
waiting on the deck with rotors running until the helideck was manned and they received
permission to depart.
Safety actions
The operator carried out a prompt internal investigation into the incident and
identified a number of potential safety actions. The following are of relevance
to this report:
‘ 1.
Carry out a Flight Planning Software review for robustness and ease of
use.
2. Carry out a review of the destination nomenclatures used for planning
applications and software.
3. Reiterate to all crews the importance of clear and unambiguous
communications.
4. Reiterate to crews the importance of re-briefing all aspects of the flight
when a significant change has been applied.’
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AAIB Bulletin: 7/2017
G-JLRW
EW/G2017/03/05
ACCIDENT
Aircraft Type and Registration: Beech 76 Duchess, G-JLRW
No & Type of Engines: 2 Lycoming O-360-A1G6D piston engines
Year of Manufacture: 1979 (Serial no: ME-165)
Date & Time (UTC): 22 March 2017 at 1050 hrs
Location: Exeter Airport, Devon
Type of Flight: Training
Persons on Board:
Crew - 2
Passengers - None
Injuries:
Crew - None
Passengers - N/A
Nature of Damage: Left pitot tube, left foot step
Commander’s Licence: Airline Transport Pilot’s Licence
Commander’s Age: 56 years
Commander’s Flying Experience: 6,936 hours (of which 440 were on type)
Last 90 days - 21 hours
Last 28 days - 13 hours
Information Source: Aircraft Accident Report Form submitted by the
pilot and subsequent AAIB enquiries
Synopsis
The aircraft was landed on the right main and nose landing gears after the left main gear
failed to extend. The lower clevis pin in the left main gear trailing link was subsequently
found to be missing.
History of the flight
The instructor reported that the aircraft was engaged on a dual training flight for the purpose
of obtaining a Multi-Engine Piston rating. The pilot under training carried out a full ‘A’ Check
prior to the flight; no defects with the landing gear were noted.
The initial part of the flight was normal; however, on lowering the landing gear the left gear
light failed to illuminate and the gear unsafe light remained on. Recycling the gear and
changing the gear indicator light bulbs failed to resolve the problem. On returning to Exeter
the emergency gear lowering procedure was attempted in accordance with the relevant
checklist, but this was unsuccessful. A flypast of the tower confirmed that the left gear had
not lowered.
The aircraft was flown in the local area for approximately 45 minutes whilst alternative
courses of action were discussed with operations and the engineering organisation. This
also allowed additional fuel to be consumed prior to landing.
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With no resolution to the problem, the pilots briefed for an approach and landing with the
instructor flying the aircraft. Both engines were shut down and the propellers feathered
when over the Runway 26 threshold. The pilot under training positioned the propeller
blades to the horizontal and isolated the fuel and electrics. Following touchdown the aircraft
veered to the left, coming to a halt on the grass beside the runway. The pilots evacuated
the aircraft normally.
Subsequent examination of the left main landing gear revealed that the lower clevis pin in
the trailing link was missing. As the pin was not recovered, it was not possible to determine
the reason for its absence.
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AAIB Bulletin: 7/2017
G-AXFN
EW/G2017/05/06
ACCIDENT
Aircraft Type and Registration: Jodel D119, G-AXFN
No & Type of Engines: 1 Continental Motors Corp C90-14F piston
engine
Year of Manufacture: 1959 (Serial no: 980)
Date & Time (UTC): 6 May 2017 at 1120 hrs
Location: Near Netherthorpe Airfield, Yorkshire
Type of Flight: Private
Persons on Board:
Crew - 1
Passengers - None
Injuries:
Crew - None
Passengers - N/A
Nature of Damage: Extensive
Commander’s Licence: Private Pilot’s Licence
Commander’s Age: 57 years
Commander’s Flying Experience: 346 hours (of which 131 were on type)
Last 90 days - 6 hours
Last 28 days - 0 hours
Information Source: Aircraft Accident Report Form submitted by the
pilot
The pilot reported that the engine failed without warning as he was turning crosswind after
takeoff. He declared a MAYDAY and had no option other than to attempt a forced landing in
a field of rape seed. The aircraft came to rest upside down but the pilot was uninjured and
able to exit using the door.
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AAIB Bulletin: 7/2017
G-ETIV
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ACCIDENT
Aircraft Type and Registration: Robin DR400/180 Regent, G-ETIV
No & Type of Engines: 1 Lycoming O-360-A3A piston engine
Year of Manufacture: 2000 (Serial no: 2454)
Date & Time (UTC): 7 December 2016 at 1327 hrs
Location: Rochester Airport, Kent
Type of Flight: Private
Persons on Board:
Crew - 1
Passengers - 1
Injuries:
Crew - None
Passengers - None
Nature of Damage: Right mainwheel spat severely cracked and
brake unit damaged
Commander’s Licence: Private Pilot’s Licence
Commander’s Age: 76 years
Commander’s Flying Experience: 863 hours (of which 728 were on type)
Last 90 days - 21 hours
Last 28 days - 0 hours
Information Source: AAIB enquiries in response to a report from
Rochester Airport
Synopsis
Following a medical procedure, the pilot asked a qualified flight instructor (FI) to act as his
“safety pilot”. The FI agreed and occupied the right seat of the pilot’s dual-controlled aircraft.
The pilot had not sought advice from an Aero-Medical Examiner (AME) prior to the flight.
The left of two parallel runways (Runway 20L) at Rochester Airport was being used for
takeoff but the pilot was unaware that Runway 20R was being used for landings when
he carried out some forced landing practice orientated towards Runway 20L. During the
second approach, when the aircraft was close to the ground, the FI in the right seat overrode
the pilot’s control inputs and turned the aircraft right, towards the parallel Runway 20R. The
right mainwheel hit and destroyed an airfield lighting unit before the pilot regained control
and landed the aircraft on Runway 20R.
The pilot assessed the accident to be a breakdown in communication and inappropriate
aircraft handling by the FI during the approach. A contributory factor was a misunderstanding
of the regulations concerning a ‘Safety Pilot’.
History of the flight
Six days after a minor eye operation, the pilot asked an FI, whom he had previously flown
with, to act as his “safety pilot” and occupy the right seat of the pilot’s dual-controlled,
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EASA aircraft for a local flight. The pilot believed his eyesight had fully recovered after the
operation1 but, as it was also six weeks since his previous flight, he thought having a ‘safety
pilot’ was a sensible precaution. However, the role of ‘safety pilot’ was not discussed before
the flight and the FI did not regard himself as the Pilot-in-Command (PIC)2.
Two parallel runways positioned close together, Runway 20 Left (20L), the ‘relief’ runway,
and Runway 20 Right (20R), the ‘main’ runway, were in use. Runway 20L has a takeoff
and landing distance of 684 m and the threshold is displaced more than 100 m upwind
from the threshold of Runway 20R (830 m). Before departure, the FI met the airfield’s
duty Flight Information Service Officer (FISO) and was told Runway 20L would be used for
takeoff but Runway 20R would be used for landing. Circuits were not permitted because
the condition of the grass was not suitable but practice forced landing (PFL) was allowed.
According to the pilot, he was not informed that Runway 20R was to be used for landing.
After takeoff, the aircraft departed the circuit area and recorded radiotelephony indicates
both the pilot and the FI spoke on the radio. Returning to the airfield, the pilot asked to
fly to the overhead to carry out a PFL and go-around. The FISO asked him to report
overhead, ready to commence, stating the circuit was right-hand but without mentioning
which of the parallel runways was in use. The pilot’s reply indicates he planned to use
“the reserve” (referring to the relief Runway 20L), but the FISO did not appreciate this.
The first PFL approach was towards Runway 20L but the aircraft was too high so the
pilot went around before attempting a second PFL, also towards Runway 20L. In the
latter stages of this approach, at the suggestion of the FI, the pilot “warmed the engine”
by advancing the throttle for a short time. He did not recall being advised to go-around
during this approach.
The surface wind was from 210º at 15 kt and the pilot believed that, by the time he was
approximately 15 ft above the ground, he was in a position from which he could have
landed on Runway 20L, albeit the aircraft was pointing left of the runway, because he
“overcompensated for the drift”. He later stated that he was about to apply power and
right rudder when, without warning, his inputs on the control column were overridden and
the aircraft turned approximately 60º right. He initially thought there was a malfunction
of the flying controls but then the FI declared “20 main” and the pilot realised the FI
was manipulating the control column and had rolled the aircraft to the right towards
Runway 20R.
The pilot believed the aircraft was now close to stalling, because the power had not been
increased, but he managed to regain control and land on Runway 20R. After taxiing
to the apron he was made aware that the right mainwheel had struck an abbreviated
precision approach path indicator (APAPI) unit positioned in the Runway 20L undershoot
(Figure 1).
Footnote
1
2
See Medical.
See EASA regulations.
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AAIB Bulletin: 7/2017
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Figure 1
APAPI units showing damage to the left unit, in a view looking along
Runway 20L from the undershoot. The units are installed for Runway 20R
which is on the right of the photograph
Following the accident, the pilot realised he and the FI should have briefed carefully
before the flight and discussed what they understood the term ‘safety pilot’ to mean and
who was to be PIC. Although after the flight the pilot signed in the aircraft technical log
(which was also the journey log) captain column, he thought he was flying as Pilot-inCommand Under Supervision (PICUS) and expected the ‘safety pilot’ to offer verbal input
during the flight. He also thought the FI, acting as ‘safety pilot’, could take control if safety
was compromised and assumed the FI would announce such action in the conventional
way, stating ‘I have control’.
Instructor’s report
The FI had logged 10,309 hours total flying experience (mostly instructional), with
5,010 hours on type and 16 hours total time within the preceding 28 days. When he
agreed to act as ‘safety pilot’ he considered it a ‘check flight’ rather than an instructional
flight, because he knew the pilot was licensed and his currency permitted him to fly with
passengers.
During the first PFL, the FI observed the aircraft was positioned too high and that the pilot
sensibly executed a go-around. On the second approach the FI saw the aircraft deviate
below the optimum glidepath so, at approximately 400 ft, his recollection was that he
suggested the pilot apply a “clearing burst of power for five seconds”. By doing this the FI
thought the engine would be warmed and the additional power would allow the aircraft to
regain the glidepath but the pilot did not apply power for as long as suggested. The FI’s
recollection was that because the aircraft was still low, he directed the pilot to go-around
but the pilot did not react.
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At a late stage in the approach the FI recognised the aircraft was “in a stalling configuration,
low and slow” and was tracking towards a rough area to the left of Runway 20L. He regarded
the situation as dangerous and tried to take control by turning the aircraft right towards
Runway 20R. However, he was prevented from taking full control because the pilot did not
relinquish control. Nevertheless, he believed his unannounced intervention was necessary
because the pilot had not, in his opinion, been flying in a “satisfactory manner”. He could
not explain why he did not announce taking or handing back control, nor why he did not
initiate a go-around.
In retrospect, the FI realised a thorough pre-flight brief ought to have been held and that he
should have enquired carefully about the pilot’s medical situation. When he checked the
relevant regulations he (like the pilot) was not aware that ‘safety pilot’ is not a recognised role
in normal operations. Although he felt his intervention prevented a more serious accident
from occurring, to refresh his skills and to learn from the event, the flight instructor carried
out subsequent training with a flight examiner.
Airfield report
The airfield duty manager was positioned to the east of the Runway 20R threshold when he
observed the aircraft approaching left of the Runway 20L approach path. He described the
aircraft as appearing to be “very low” and “very slow”. He estimated it was two feet above
the ground, flying relatively slowly and still downwind and to the left of the Runway 20L
threshold when it abruptly veered right towards Runway 20R. He had the impression the
aircraft was close to stalling when the right mainwheel struck the left APAPI unit, which
detached from its mountings.
EASA regulations
Medical
The pilot possessed an EU Class 2 Medical Certificate valid until 8 November 2017 with one
limitation, that he have available corrective spectacles and carry a spare set of spectacles
(VNL). On 1 December 2016 he underwent a minor operation to remove a cataract from his
right eye and was told he could drive a motor vehicle two days later. He did not seek advice
from his AME but was apparently informed during a hospital check on 4 December that the
sight in his right eye was “good, 20/20”3.
A day after the accident, an ophthalmologist stated the pilot’s uncorrected vision was 20/20
or better in each eye. The pilot was unable to explain why he did not speak to his AME
before flying, except that he believed his eyesight had been adequately checked and that
he had thought he was doing the safest thing by flying with an FI, who could take control if
necessary.
Footnote
3
Visual acuity of 20/20 is a US measurement for which the UK equivalent is 6/6. This is better than a score
of 6/12 which is the visual acuity a pilot should demonstrate in each eye, with or without corrective lenses,
when tested for an EASA Class 2 Medical Certificate.
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Annexe IV to Commission Regulation (EU) No 1178/2011 states at PART MED.A.020,
‘Decrease in medical fitness
a)
b)
Licence holders shall not exercise the privileges of their licence and
related ratings or certificates at any time when they:
(1)
are aware of any decrease in their medical fitness which might
render them unable to safely exercise those privileges;
(2)
take or use any prescribed or non-prescribed medication which
is likely to interfere with the safe exercise of the privileges of the
applicable licence;
(3)
receive any medical, surgical or other treatment that is likely to
interfere with flight safety.
In addition, licence holders shall, without undue delay, seek aero-medical
advice when they:
(1)
have undergone a surgical operation or invasive procedure;
(2)
have commenced the regular use of any medication;
(3)
have suffered any significant personal injury involving incapacity to
function as a member of the flight crew;’
The PART MED regulations also state (paragraph MED.B.001) that a pilot, who does not fully
comply with the requirements for a Class 2 medical certificate, can have a certificate issued
with a limitation code if it is assessed they can perform their duties safely by complying with
that limitation. If an:
‘Operational Safety Pilot Limitation (OSL)’ is placed on a pilot’s medical
certificate then he or she ‘shall only operate an aircraft if another pilot fully
qualified to act as pilot-in-command on the relevant class or type of aircraft
is carried on board, the aircraft is fitted with dual controls and the other pilot
occupies a seat at the controls.’
The related Guidance Material states that this ‘Safety Pilot ’is to be aware of the incapacity
which the pilot might suffer from and be prepared to take over the controls during flight.
The term ‘Safety Pilot’ only applies to pilots with the limitation ‘OSL’ on their Class 2 medical
certificate and this pilot had no such limitation. Where an ‘OSL’ limitation does apply, the
‘Safety Pilot’ has to be the PIC.
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Pilot-in-command
Regulation (EC) No 216/2008 of the European Parliament is EASA’s ‘Basic Regulation’ and
Annex IV, paragraph 1.c. states:
‘Before every flight, the roles and duties of each crew member must be defined.
The pilot in command must be responsible for the operation and safety of the
aircraft and for the safety of all crew members, passengers and cargo on
board.’
The ‘Basic Regulation’ also states, at Article 7, that:
‘Except when under training, a person may only act as a pilot if he or she
holds a licence and a medical certificate appropriate to the operation to be
performed.’
Further guidance on a PIC’s responsibilities during non-commercial operations are given in
Commission Regulation (EU) No 1178/2011. PART-NCO.GEN.105 states at paragraph (f):
‘During flight, the pilot-in-command shall…remain at the controls of the aircraft
at all times except if another pilot is taking the controls.’
Also, in accordance with PART-NCO.OP.130 the PIC is to:
‘ensure that before or, where appropriate, during the flight, passengers are
given a briefing on emergency equipment and procedures.’
Flight instructors
Subpart J to Annexe I to Commission Regulation (EU) No 1178/2011 states that the
privileges of a FI certificate are to conduct flight instruction for the issue, revalidation or
renewal of a licence or rating. For an FI to perform such duties, on an aircraft for which he
or she is suitably qualified, he or she will be the PIC for the flight and will sign the journey
log as the person in charge. There is no EASA or CAA definition for the term ‘check flight’,
as used by the FI.
A pilot of a single crew aircraft who flies alone or with passengers is responsible for the
safe conduct of the flight and logs the time as PIC. However, when accompanied by an
FI, exercising the privileges of an FI certificate, a pilot logs ‘dual instruction time’. The
exception to this is when the FI does not influence or control the aircraft’s flight and only
observes the other pilot, allowing the FI to certify the pilot’s log book to state they acted as
‘student pilot-in-command (SPIC)’ or as ‘pilot-in-command under supervision’.
AAIB Comment
Prior to the flight the pilot and FI had not appropriately briefed and agreed their roles and
procedures. Both the pilot and the FI thought the FI could act as ‘safety pilot’, providing
verbal advice from the right seat, while being available to take control if the pilot became
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incapacitated. However, the role of ‘Safety Pilot’ was not applicable because the pilot’s
medical certificate was not endorsed ‘OSL’ and, because the FI did not sign for the aircraft as
PIC, his role being that of a passenger and he should not have tried to perform instructional
duties.
Although not causal to the accident, the pilot had an operation to remove a cataract from
his right eye. Following the procedure he should have consulted with his AME as it was a
surgical operation and also to ensure that the treatment he had received did not ‘interfere
with flight safety’.
Safety actions
Following an investigation, a safety action was taken at the airfield to ensure
pilots are told the runway in use when they call on the radio prior to arrival.
In May 2017 the CAA published CAP 1535, ‘The Skyway Code’4 which is
intended to provide General Aviation pilots involved in non-commercial and
flight training operations with practical guidance on the operational, safety and
regulatory issues relevant to their flying. ‘The Skyway Code’ includes a section
on the responsibilities of the Pilot in Command in a format which is intended to
be more accessible than from regulatory documents.
To further clarify the term ‘Safety Pilot’ when used with an ‘Operational Safety
Pilot Limitation (OSL)’ placed on a Medical Certificate, the CAA will produce
an article for ‘Clued Up’, its magazine for the general aviation community.
Additionally, the CAA will also ask the General Aviation Safety Council (GASCO)
to publish the same article in its Flight Safety Bulletin.
Footnote
4
See http://www.caa.co.uk/General-aviation/Safety-information/The-Skyway-Code/
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AAIB Bulletin: 7/2017
G-TIVV
EW/G2017/05/20
ACCIDENT
Aircraft Type and Registration: Aerotechnik EV-97 Eurostar, G-TIVV
No & Type of Engines: 1 Rotax 912-UL piston engine
Year of Manufacture: 2005 (Serial no: PFA 315-14435)
Date & Time (UTC): 17 May 2017 at 1125 hrs
Location: Yarrow Valley, Scottish Borders
Type of Flight: Private
Persons on Board:
Crew - 1
Passengers - 1
Injuries:
Crew - None
Passengers - None
Nature of Damage: Damage to nose landing gear, propeller and
lower fuselage panels
Commander’s Licence: National Private Pilot’s Licence
Commander’s Age: 67 years
Commander’s Flying Experience: 444 hours (of which 112 were on type)
Last 90 days - 6 hours
Last 28 days - 3 hours
Information Source: Aircraft Accident Report Form submitted by the
pilot
The pilot was taking off for a local flight, with a friend as his passenger. After reaching flying
speed, with the wheels just off the ground, he realised that he could not move the control
stick back, as usual. As a result, the aircraft was not climbing away from the surface and the
pilot aborted the takeoff. The aircraft landed back on the airstrip but bounced and pitched
up, before appearing to stall and impact the ground in a nose-down attitude. It came to
rest with its nose landing gear collapsed and damage to the propeller and lower fuselage
panels. Neither occupant was injured.
The pilot examined the aircraft afterwards and all the controls worked normally. He
concluded that there may have been a restriction in the cockpit, which prevented the control
stick from moving rearwards normally. He noted that the passenger had been carrying a
bulky camera or could have been obstructing the controls in some other way.
General Aviation Safety Sense Leaflet 02 – ‘Care of Passengers’, published by the CAA,
gives details of information that passengers should be given before they fly. This includes
the need to keep items secure and away from the controls, to prevent restrictions.
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AAIB Bulletin: 7/2017
D-MNBU
EW/G2016/08/20
ACCIDENT
Aircraft Type and Registration: Ikarus C22, D-MNBU
No & Type of Engines: 1 C22 Rotax 912 UL piston engine
Year of Manufacture: 1994 (Serial no: 9409-3597)
Date & Time (UTC): 25 August 2016 at 0800 hrs
Location: Popham Airfield, Hampshire
Type of Flight: Private
Persons on Board:
Crew - 1
Passengers - None
Injuries:
Crew - 1 (Minor)
Passengers - N/A
Nature of Damage: Nosewheel and left mainwheel
Commander’s Licence: Other
Commander’s Age: 62 years
Commander’s Flying Experience: 40 hours (of which 40 were on type)
Last 90 days - 25 hours
Last 28 days - 15 hours
Information Source: Aircraft Accident Report Form submitted by the
pilot
D-MNBU was landing on Runway 08 at Popham Airfield during a competition. It was
performing what the pilot described as a “spot turn” manouevre, in which the pilot shuts
down the aircraft’s engine at height and then glides the aircraft to land. The pilot reported
Popham’s weather to be clear, with 5 kt wind and a temperature of 18°C. The runway, which
has a grass surface, was reported as being soft.
Shortly before landing, the aircraft’s speed became too slow, causing it to stall on to the
runway. The nosewheel and left main landing gear were damaged, and the pilot sustained
minor injuries.
The pilot believed that the accident was caused by paying insufficient attention to the
aircraft’s speed during a challenging manoeuvre.
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AAIB Bulletin: 7/2017
Miscellaneous
This section contains Addenda, Corrections
and a list of the ten most recent
Aircraft Accident (‘Formal’) Reports published
by the AAIB.
The complete reports can be downloaded from
the AAIB website (www.aaib.gov.uk).
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AAIB Bulletin: 7/2017
TEN MOST RECENTLY PUBLISHED
FORMAL REPORTS
ISSUED BY THE AIR ACCIDENTS INVESTIGATION BRANCH
2/2011
Aerospatiale (Eurocopter) AS332 L2 Super Puma, G-REDL
11 nm NE of Peterhead, Scotland
on 1 April 2009.
Published November 2011.
2/2015 Boeing B787-8, ET-AOP
London Heathrow Airport
on 12 July 2013.
Published August 2015.
1/2014 Airbus A330-343, G-VSXY
at London Gatwick Airport
on 16 April 2012.
3/2015
Eurocopter (Deutschland)
EC135 T2+, G-SPAO
Glasgow City Centre, Scotland
on 29 November 2013.
Published October 2015.
Published February 2014.
2/2014 Eurocopter EC225 LP Super Puma
G-REDW, 34 nm east of Aberdeen,
Scotland on 10 May 2012
and
G-CHCN, 32 nm south-west of
Sumburgh, Shetland Islands
on 22 October 2012.
Published June 2014.
3/2014
Agusta A109E, G-CRST
Near Vauxhall Bridge,
Central London
on 16 January 2013.
Published September 2014.
1/2016 AS332 L2 Super Puma, G-WNSB
on approach to Sumburgh Airport
on 23 August 2013.
Published March 2016.
2/2016
Saab 2000, G-LGNO
approximately 7 nm east of Sumburgh Airport, Shetland
on 15 December 2014.
Published September 2016.
1/2017 Hawker Hunter T7, G-BXFI
near Shoreham Airport
on 22 August 2015.
1/2015 Airbus A319-131, G-EUOE
London Heathrow Airport
on 24 May 2013.
Published March 2017.
Published July 2015.
Unabridged versions of all AAIB Formal Reports, published back to and including 1971,
are available in full on the AAIB Website
http://www.aaib.gov.uk
© Crown copyright 2017
69
Air Accidents Investigation Branch
Farnborough House
Berkshire Copse Road
Aldershot
Hants GU11 2HH
AAIB Bulletin: 7/2017
GLOSSARY OF ABBREVIATIONS
aal
Tel: 01252 510300
Fax: 01252 376999
Press enquiries: 0207 944 3118/4292
http://www.aaib.gov.uk
AAIB investigations are conducted in accordance with
Annex 13 to the ICAO Convention on International Civil Aviation,
EU Regulation No 996/2010 and The Civil Aviation (Investigation of
Air Accidents and Incidents) Regulations 1996.
The sole objective of the investigation of an accident or incident under these
Regulations is the prevention of future accidents and incidents. It is not the
purpose of such an investigation to apportion blame or liability.
Accordingly, it is inappropriate that AAIB reports should be used to assign fault
or blame or determine liability, since neither the investigation nor the reporting
process has been undertaken for that purpose.
AAIB Bulletins and Reports are available on the Internet
http://www.aaib.gov.uk
This bulletin contains facts which have been determined up to the time of compilation.
Extracts may be published without specific permission providing that the source is duly acknowledged, the material is
reproduced accurately and it is not used in a derogatory manner or in a misleading context.
Published 13 July 2017
Cover picture courtesy of Stephen R Lynn
© Crown copyright 2017
Published by the Air Accidents Investigation Branch, Department for Transport
Printed in the UK on paper containing at least 75% recycled fibre
(www.srlynnphotography.co.uk)
ISSN 0309-4278
above airfield level
ACAS
Airborne Collision Avoidance System
ACARS
Automatic Communications And Reporting System
ADF
Automatic Direction Finding equipment
AFIS(O)
Aerodrome Flight Information Service (Officer)
agl
above ground level
AIC
Aeronautical Information Circular
amsl
above mean sea level
AOM
Aerodrome Operating Minima
APU
Auxiliary Power Unit
ASI
airspeed indicator
ATC(C)(O) Air Traffic Control (Centre)( Officer)
ATIS
Automatic Terminal Information System
ATPL
Airline Transport Pilot’s Licence
BMAA
British Microlight Aircraft Association
BGA
British Gliding Association
BBAC
British Balloon and Airship Club
BHPA
British Hang Gliding & Paragliding Association
CAA
Civil Aviation Authority
CAVOK
Ceiling And Visibility OK (for VFR flight)
CAS
calibrated airspeed
cc
cubic centimetres
CG
Centre of Gravity
cmcentimetre(s)
CPL Commercial Pilot’s Licence
°C,F,M,T
Celsius, Fahrenheit, magnetic, true
CVR Cockpit Voice Recorder
DME
Distance Measuring Equipment
EAS
equivalent airspeed
EASA
European Aviation Safety Agency
ECAM
Electronic Centralised Aircraft Monitoring
EGPWS
Enhanced GPWS
EGT
Exhaust Gas Temperature
EICAS
Engine Indication and Crew Alerting System
EPR
Engine Pressure Ratio
ETA
Estimated Time of Arrival
ETD
Estimated Time of Departure
FAA
Federal Aviation Administration (USA)
FDR Flight Data Recorder
FIR
Flight Information Region
FL
Flight Level
ftfeet
ft/min
feet per minute
g
acceleration due to Earth’s gravity
GPS
Global Positioning System
GPWS
Ground Proximity Warning System
hrs
hours (clock time as in 1200 hrs)
HP
high pressure
hPa
hectopascal (equivalent unit to mb)
IAS
indicated airspeed
IFR
Instrument Flight Rules
ILS
Instrument Landing System
IMC
Instrument Meteorological Conditions
IP
Intermediate Pressure
IR
Instrument Rating
ISA
International Standard Atmosphere
kgkilogram(s)
KCAS
knots calibrated airspeed
KIAS
knots indicated airspeed
KTAS
knots true airspeed
kmkilometre(s)
ktknot(s)
lbpound(s)
LP
low pressure
LAA
Light Aircraft Association
LDA
Landing Distance Available
LPC
Licence Proficiency Check
mmetre(s)
mbmillibar(s)
MDA
Minimum Descent Altitude
METAR
a timed aerodrome meteorological report
minminutes
mmmillimetre(s)
mph
miles per hour
MTWA
Maximum Total Weight Authorised
NNewtons
Main rotor rotation speed (rotorcraft)
NR
N g
Gas generator rotation speed (rotorcraft)
engine fan or LP compressor speed
N1
NDB
Non-Directional radio Beacon
nm
nautical mile(s)
NOTAM
Notice to Airmen
OAT
Outside Air Temperature
OPC
Operator Proficiency Check
PAPI
Precision Approach Path Indicator
PF
Pilot Flying
PIC
Pilot in Command
PNF
Pilot Not Flying
POH
Pilot’s Operating Handbook
PPL
Private Pilot’s Licence
psi
pounds per square inch
QFE
altimeter pressure setting to indicate height
above aerodrome
QNH
altimeter pressure setting to indicate
elevation amsl
RA
Resolution Advisory
RFFS
Rescue and Fire Fighting Service
rpm
revolutions per minute
RTFradiotelephony
RVR
Runway Visual Range
SAR
Search and Rescue
SB
Service Bulletin
SSR
Secondary Surveillance Radar
TA
Traffic Advisory
TAF
Terminal Aerodrome Forecast
TAS
true airspeed
TAWS
Terrain Awareness and Warning System
TCAS
Traffic Collision Avoidance System
TGT
Turbine Gas Temperature
TODA
Takeoff Distance Available
UHF
Ultra High Frequency
USG
US gallons
UTC
Co-ordinated Universal Time (GMT)
VVolt(s)
V1
Takeoff decision speed
V2
Takeoff safety speed
Rotation speed
VR
VREF
Reference airspeed (approach)
VNE
Never Exceed airspeed
VASI
Visual Approach Slope Indicator
VFR
Visual Flight Rules
VHF
Very High Frequency
VMC
Visual Meteorological Conditions
VOR
VHF Omnidirectional radio Range
AAIB Bulletin 7 /2017
AAIB Bulletin 7/2017
AAIB Bulletin
7/2017
TO REPORT AN ACCIDENT OR INCIDENT
PLEASE CALL OUR 24 HOUR REPORTING LINE
AAIB
Air Accidents Investigation Branch
01252 512299
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