null  null
Editorial
# 06 July 2008
Yannick MALINGE
Vice President
Flight Safety
Content
Dear Customers and Aviation Safety colleagues,
The Airbus Safety Magazine . . . . . . . . . . . . . . . . .
Runway excursions remain one of the three main accident
categories, accounting for about a quarter of all accidents
in 2007.
News
The following two main contributing factors to these events
have been well identified in the past by the aviation
community :
• Unstabilized approaches
• Lack of go-around decision
As announced in the previous issue of this magazine, the
“A320/ Runway overrun” article that you will find hereafter
illustrates very well the need to repeat the lessons learnt
from these occurrences. This is particularly true for the
new entrants in the aviation community.
On a different subject, we are very pleased to publish the
article titled “FCTL check after EFCS reset on ground”,
as it has been co-written by an Airbus operator.
Let me take this opportunity to remind you that we
encourage our customer to share safety information that
could bring added value to other Airbus operators, by
providing airline safety articles for this magazine.
...................................................
Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
A320/ Runway overrun
M. Baillion
FCTL check after EFCS
reset on ground
K. Tritschler & A. Urdiroz
.........................
A320/ Possible consequences
of VMO/MMO exceedance
M. Palomèque
.......................................
A320/ Prevention of tailstrikes
M. Palomèque
.......................................
Low fuel situations awareness
F. Marani
...............................................
Rudder pedal Jam
J. Rendu
I hope you will enjoy reading this sixth issue of Safety
First, and look forward to meet you at the 15th Flight Safety
Conference in Paris.
.............................................
...............................................
Why do certain AMM tasks require
equipment resets?
D. Harris . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Slide/Raft Improvement
Yours sincerely
F. Sauvage
Yannick MALINGE
Vice President Flight Safety
............................................
Cabin attendant falling through
the avionics bay access panel in cockpit
P-O. Guenzel
.........................................
1
2
3
4
10
14
18
22
27
29
31
33
Safety First
1
# 06 July 2008
The Airbus Safety Magazine
Safety First
The Airbus Safety Magazine
For the enhancement of safe flight through
increased knowledge and communications.
Safety First is published by the Flight Safety Department
of Airbus. It is a source of specialist safety information
for the restricted use of flight and ground crew members
who fly and maintain Airbus aircraft. It is also distributed
to other selected organisations.
requirements or technical orders. The contents do not
supersede any requirements mandated by the State of
Registry of the Operator’s aircraft or supersede or amend
any Airbus type-specific AFM, AMM, FCOM, MEL
documentation or any other approved documentation.
Material for publication is obtained from multiple sources
and includes selected information from the Airbus Flight
Safety Confidential Reporting System, incident and
accident investigation reports, system tests and flight
tests. Material is also obtained from sources within the
airline industry, studies and reports from government
agencies and other aviation sources.
Articles may be reprinted without permission, except where
copyright source is indicated, but with acknowledgement
to Airbus. Where Airbus is not the author, the contents of
the article do not necessarily reflect the views of Airbus,
neither do they indicate Company policy.
All articles in Safety First are presented for information
only and are not intended to replace ICAO guidelines,
standards or recommended practices, operator-mandated
Contributions, comment and feedback are welcome. For
technical reasons the editors may be required to make editorial
changes to manuscripts, however every effort will be made
to preserve the intended meaning of the original. Enquiries
related to this publication should be addressed to:
Airbus
Flight Safety Department (GSE)
1, rond point Maurice Bellonte
31707 Blagnac Cedex - France
Contact: Marie-Josée Escoubas
E-mail: [email protected]
Fax: +33 (0)5 61 93 44 29
Safety First
# 06 July 2008
Safety First is published
by Airbus S.A.S
1, rond point Maurice Bellonte
31707 Blagnac Cedex / France
Editor:
Yannick Malinge,
Vice President Flight Safety
Concept Design by
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© Airbus S.A.S. 2008 – All rights reserved. Confidential and proprietary documents.
By taking delivery of this Brochure (hereafter “Brochure”), you accept on behalf of your
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2
News
15th Flight Safety
Conference
The planning for this year’s conference is well
underway. It will be held from the 20th to the 23rd
of October in Paris. A provisional agenda has been
defined and the invitations have been sent out in
June. If you are an Airbus customer, and have not
yet received an invitation, please contact Nuria
Soler at the address below. Please note that this
is a conference for Airbus and our customers only.
We do not accept outside parties into the
conference so as to ensure that we can have an
open forum for everybody to share information.
As always we welcome presentations from you.
The conference is a forum for everybody to share
information, so if you have something you believe
will benefit other operators and/or Airbus, then
please contact us.
We look forward to meeting you all at the conference !
Contact: Mrs Nuria Soler
E-mail: [email protected]
fax: +33 (0) 561934429
Safety First
3
# 06 July 2008
The Airbus Safety Magazine
Information
Magazine distribution
If you wish to subscribe to Safety First, please fill
out the subscription form that you will find at the
end of this issue.
Please note that the paper copies will only be
forwarded to professional addresses.
Your articles
This magazine is a tool to help share information,
therefore we rely on your inputs. We are keen to
receive articles from customers, that we can pass
along to other operators through the magazine.
If you wish to share your experience, please contact
us.
Contact: Marie-Josée Escoubas
[email protected]
Fax: +33 (0) 5 61 93 44 29
Safety Information
on the Airbus websites
On the different Airbus websites we are building
up more and more safety relevant information for
you to use.
The present and previous issues of Safety First
can be accessed to in the Flight Operations
Community- Safety and Operational Materials
chapter-, in the secure area of
www.airbusworld.com
Or directly at the secure site at:
https://w3.airbus.com/
If you do not yet have access rights, then contact
your IT administrator or refer to “Registration
information” (top left of web page).
Other safety and operational expertise publications,
like the Flight Operation Briefing Notes (FOBN),
Getting to Grips with… brochures, e-briefings etc…
are regularly released as well in the Flight Operations
Community at the above sites.
The FOBN, referred to in some articles in this issue,
may as well be found on the Safety Library room
of the general public Airbus website at
http://www.airbus.com/en/corporate/ethics/safety_lib/
Flight Safety
Hotline:
+33 (0)6 29 80 86 66
E-mail:
[email protected]
4
A320/
Runway overrun
By: Marc BAILLION
Flight Safety Director
1 Introduction
It stopped approximately 200 meters beyond the
runway limit and the 156 occupants were able to
evacuate the plane safely. There was no post
impact fire, but the aircraft suffered a hull loss.
The following sequence of events has been retrieved
from the DFDR and CVR. Data from the latter is
incomplete as the Captain’s voice was not audible.
Flight conditions at 4 700ft :
Runway excursions, together with Controlled Flight
Into Terrain (CFIT), are one of the main categories
of incidents and accidents. In the last two years,
ten runway excursions were reported to Airbus.
This article will describe on of these occurrences,
where the aircraft was damaged beyond economical repair
The root causes of this event are common to many
other runway excursions, and it is therefore
worthwhile to share the lessons learned from this
accident and to repeat the following key safety
messages:
• Fly stabilized approaches
• Be go-around minded
2 Description
of the event
An A320 performed a visual approach to a
runway 12. The aircraft landed at 6h23’ local time
and overran the end of the 1966 meter long runway
at a speed of approximately 85kt.
The aircraft was performing a visual approach.
Gross weight was 64t (Max landing weight is 64.5t)
Configuration clean (Slat 0° / Flaps 0°) with landing
gears up and locked.
Autopilot 1 was engaged in DES (longitudinal mode)
and NAV (lateral mode). Both Flight Directors (FD)
were engaged. ATHR was engaged in thrust mode.
Captain was the Pilot Flying (PF).
Selected altitude on FCU was 3 000ft.
Aircraft heading was 155°.
Wind speed was 23kt, and wind direction 300°.
This resulted in a 20kt tailwind and a 13kt right
crosswind.
Speed target was managed by the FMGC and
was equal to 285kt.
CAS was 306kt
Vapp = 138kt
Safety First
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# 06 July 2008
The Airbus Safety Magazine
Approach
Approaching 3 000ft, The crew contacted ATC :
- F/O : “… approaching 10 DME 3 000”
- ATC : Roger and wind is calm.
Report finals runway 12”.
- F/O : “Check finals runway 12 …”.
As the aircraft approached 3 000ft, the A/P vertical
mode changed to Altitude Acquire (ALT*) then to
Altitude Hold (ALT). The ATHR changed to speed
mode.
The A/P vertical mode was then changed to Flight
Path Angle (FPA), with a selected –3° FPA target.
The aircraft descended accordingly.
The selected FPA was then changed to 0° and the
aircraft leveled off at 2 800ft RA.
The crew selected configuration 11 and, 3 seconds
later, landing gears down.
Slats and flaps surfaces reached the position FULL
about 3s after the crew selected this configuration. Speedbrakes started to retract (speedbrakes
are inhibited in configuration FULL on A320).
The crew armed the ground spoilers, and the
selected FPA was successively changed to –3.6°,
then to –5.5° and –7° after having selected
configuration 22 at about 2 600ft RA (CAS was
198kt ; VFE = 200kt).
A Single Chime (SC) sounded, which corresponds
to the “SPD BRK DISAGREE” caution, triggered
because of the difference between the actual
position of the speedbrakes (retracted) versus the
commanded position (extended).
The F/O announced “Still high” and immediately
after “Too close”.
The speedbrake lever remained in the extended
position until the end of recorded data.
The ground spoilers were not rearmed.
At 2 300ft RA, the Captain disconnected the A/P
and disengaged both FD.
ATC announced “Wind is calm3, cleared to land
runway 12”.
At 1 600ft RA, configuration 3 was selected (CAS
was 186kt; VFE = 185kt).
4
At about 1 150ft RA, during the LH turn to intercept
the runway centerline, configuration FULL5 was
selected (CAS was 170kt; VFE = 177kt) and within
about one second, speedbrake lever was pushed
aft to command extension. To do that, the crew
disarmed the ground spoilers.
The F/O announced “High speed he” and
immediately after “Let’s circle again it’s too high”
followed by “High”.
Configuration 1: Slats 18° / Flaps 0°
Configuration 2: Slats 22° / Flaps 15°
3
The wind information was not reliable because the wind
indication system had been out of order for several months.
A NOTAM had been issued, but the crew was not aware.
1
2
The Captain then pushed the stick and increased
the rate of descent up to 1 900ft/min.
At 600ft RA the EGPWS alarm “Sink Rate” triggered
and sounded twice.
The Captain decreased the nose-down pitch from
–6.5° to –2.5°. The aircraft rate of descent decreased.
At 500ft RA CAS was approximately 170kt
(Vapp+ 32), and the rate of descent was about
1 800ft/min.
F/O said “Our speed is too high. We can make
another circuit. How about that”.
The Captain continued the approach.
6
Both brake pedals were kept pressed while Autobrake
mode selection was changed to MAX.
This had no effect because the Autobrake was not
activated.
Landing
At 200ft RA the wind characteristics were: 11kt
tailwind and 6kt crosswind from the left.
At 170ft RA, Autobrake MED was selected.
At about 150ft RA, the EGPWS alarm “Sink Rate”
triggered and sounded twice.
The Captain pulled the stick and adjusted the pitch
from –2.5° nose down to +1° nose up (reached at
about 50ft). The aircraft rate of descent decreased.
At approximately 50ft RA, both thrust levers were
retarded to idle. CAS was 159kt (Vapp + 21).
The aircraft flew over the runway 12 threshold, at
a height of 35ft.
F/O called out “Speed”.
The aircraft floated above the runway during 9s
and both main landing gears touched down at
about 740m beyond the runway 12 threshold (1
226m of runway left), CAS was 150kt (Vapp+12).
The aircraft bounced and touched down again at
1 070m beyond the runway threshold (896m of
runway left). CAS was 146kt (Vapp+8), ground
speed was 158kt.
Both brake pedals were fully pressed and the aircraft
longitudinal deceleration reached 0.3g.
The thrust levers remained at idle and no reverser
thrust was selected.
Note: Pressing the brake pedals normally
deactivates the Autobrake. Here, the
Autobrake did not activate since the ground
spoilers did not deploy as they had been
disarmed upon speedbrake selection.
Ground spoilers, even disarmed, extend at
touchdown at reverser thrust selection.
However, as mentioned above, in this event
reverser thrust was not selected.
Configuration 3 : Slats 22° / Flaps 20°
Configuration FULL: Slats 27° / Flaps 35°
6
Spoilers 2 to 4 act as speed brakes
4
The Captain then pulled full back stick and the
thrust levers were set to TOGA for about 2s (while
the aircraft was 316 meters from the runway end)
and back to idle.
CAS was approximately 113kt.
The brake pedals were slightly released, and then
were fully pressed again7.
The aircraft left the runway at a ground speed of
approximately 85kt, crossed a field, descended a
steep gradient and came to a stop in some trees.
3 Key Points
• The aircraft was performing a visual approach
to the 1 966m long runway 12, with A/P1 and
both FD engaged.
• A/P was disconnected at 2 300ft RA.
• At about 1 200ft RA, during left final turn,
configuration FULL was selected and immediately
after, speed brake lever was pushed aft. This
disarmed the ground spoilers.
• At 500ft RA, CAS was approximately 170kt
(Vapp+32) and the rate of descent was about
1 800ft/min.
• The approach was never stabilized.
• The aircraft first touched down at 740m from
the runway threshold (1 226m left), CAS was
150kt (Vapp+12).
• The second touch down occurred at about
1 070m from the runway threshold (896m left),
CAS was 146kt (Vapp+8).
• Both thrust levers remained at idle. No thrust
reverser was selected.
• The crew performed manual braking, deceleration
rate reached 0.3g.
• The aircraft left the runway at about 85kt.
Note : With ground spoilers deployed at touch
down without reversers, the aircraft
would have stopped at about 350m
before the runway end
(400m if reversers had been selected).
5
7
Since CAPT and F/O brake pedals are mechanically linked, the
DFDR does not allow to determine who actually pressed on the
pedals.
Safety First
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# 06 July 2008
The Airbus Safety Magazine
4 Lessons learned
The approach was never stabilized.
In addition, the Visual Approach SOP contained
in FCOM 3.03.20 indicates :
“Have the aircraft stabilized by 500 feet AGL, on
the correct approach path at VAPP (or ground
speed mini) with the appropriate thrust applied. If
not stabilized, a go-around should be considered.”
An unstabilized approach may result from an
inappropriate evaluation of the situation and
inadequate time management to plan, prepare
and execute the approach.
A go-around should be considered as well when
confusion exists about :
• The use of automation
• The aircraft’s response
This adequate preparation should be done through
briefings, which are safety nets to ensure:
• Shared evaluation of the situation and setting of
common objectives.
• A clear definition of the tasks and task sharing
to be performed.
• A mutually agreed action plan, which includes
preparing a go-around strategy if, for unexpected
reasons, the approach has to be aborted.
4.3 Ground spoilers, thrust reversers
and auto brake
During the approach, the crew should then monitor
flight parameters and external conditions carefully
in order to detect deviations from the planned
approach, as even small deviations may lead to
reduced safety margins.
Airbus recommends adherence to the SOP in FCOM
3.03.22. p5/6. The touchdown procedures have
been revised in June 2008 (REV 42) to include, among
other modifications, notes reminding crews that:
• If ground spoilers are not armed, ground spoilers
extend at reverser thrust selection on both engines.
• Autobrake is inhibited if the ground spoilers do
not extend.
4.1 Stabilized approach
FCOM 3.03.20 p.1, Visual Approach, indicates:
“Perform the approach on a nominal 3-degree
glideslope using visual references. Approach to be
stabilized by 500 feet AGL on the correct approach
path, in the landing configuration, at VAPP.”
4.2 Be go-around minded
The Flight Crew Training Manual 02.070 Approach
Briefing reads as follows :
“The crew must be ready mentally for go-around
at any stage of the approach. Should a failure occur
above 1 000 ft RA, all ECAM actions (and DH
amendment if required) should be completed before
reaching 1 000 ft RA, otherwise a go-around should
be initiated. This ensures proper task sharing for
the remainder of the approach. Any alert generated
below 1 000 ft should lead to a go-around.“
The ground spoilers were disarmed when the crew
selected the speed brakes.
At touch down, the PF did not select the reversers
and the PNF did not check the ground spoilers
extension nor the reversers deployment.
The revised touchdown procedures are shown
hereafter:
8
*
STANDARD OPERATING PROCEDURES
3.03.22
P 5
LANDING
SEQ 001
REV 42
At touchdown :
− REV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . MAX
. Select MAX REV immediately after the main landing gear touches down.
If the airport regulations restrict the use of thrust reversers, select and maintain the
thrust levers in reverse idle position until taxi speed is reached.
A slight pitch up that can be easily controlled by the pilot, may occur when the
thrust reversers are deployed before the nose landing gear touches down.
Lower the nosewheel without undue delay.
. The PNF continues to monitor the attitude.
. In the case of an engine failure, the use of the remaining thrust reverser is
recommended.
. Braking may begin before the nosewheel has touched down, if required for
performance reasons. However, when comfort is the priority, the flight crew should
delay braking until the nosewheel has touched down.
During rollout, the flight crew should avoid sidestick inputs (either lateral or
longitudinal).
If directional control problems are encountered, the flight crew should reduce thrust
to reverse idle until directional control is satisfactory.
. After reverse thrust is selected, the flight crew must perform a full stop landing.
R
R
R
R
R
R
− GROUND SPOILERS . . . . . . . . . . . . . . . . . . . . . . . . . CHECK/ANNOUNCE
Check that the ECAM WHEEL page displays the ground spoilers extended after
touchdown.
. If no ground spoilers are extended :
− Verify and confirm that both thrust levers are set to IDLE or REV detent
− Set both thrust reverser levers to REV MAX, and fully press the brake pedals.
R
R
Note : If ground spoilers are not armed, ground spoilers extend at reverser thrust
selection.
R
R
R
− REVERSERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CHECK/ANNOUNCE
Check that the ECAM E/WD page displays that the reverse deployment is as
expected (REV green).
− DIRECTIONAL CONTROL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ENSURE
. Use rudder pedals for directional control.
. Do not use the nosewheel steering control handle before reaching taxi speed.
− BRAKES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . AS RQRD
. Monitor the autobrake, if it is on. When required, brake with the pedals.
. Although the green hydraulic system supplies the braking system, if pedals are
pressed rapidly, a brake pressure indication appears briefly on the BRAKE PRESS
indicator.
R
Note : If no ground spoilers are extended, the autobrake is not activated.
Safety First
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# 06 July 2008
The Airbus Safety Magazine
STANDARD OPERATING PROCEDURES
LANDING
R
R
R
R
3.03.22
P 6
SEQ 001
REV 42
− DECELERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . CHECK/ANNOUNCE
The deceleration is felt by the flight crew, and confirmed by the speed trend on the
PFD.
The deceleration may also be confirmed by the DECEL light (if autobrake is on).
5 Conclusion
This event illustrates the need to prepare each
approach and to perform an adequate briefing,
which will help the crews in:
• The execution of a stabilized approach
• The recognition of the need to carry out a timely
go-around
• The performance of a safe go-around
Runway excursions remains a major category of
incidents and accidents.
Avoiding them requires following two golden rules :
• Fly stabilized approaches
• Be go-around minded
This message is essential as insufficient preparation
of the approach and/or minor deviations in the
flight path may result in major safety consequences.
Airbus also recommends giving consideration to
the Flight Operation Briefing Notes (FOBN)
“Flying Stabilized Approach”, FOBN “Descent and
Approach Profile Management” and FOBN “Aircraft
Energy Management during Approach”.
The Flight Operation Briefing Notes are available
on the Airbus website at the following address and
can be downloaded at:
http://www.airbus.com/en/corporate/ethics/safety_lib/
10
FCTL check
after EFCS reset
on ground
By: Kristjof TRITSCHLER
Flight Safety Manager
Germanwings
Albert URDIROZ
Flight Safety Director
Airbus
1 Introduction
Recently, an A320 operated by Germanwings
experienced an uncommanded spoiler extension
in flight.
On review of this event, the authors felt it was worth
writing an article to describe the sequence of events
that led to this occurrence, and to highlight the
need to repeat the Flight Control Check after
resetting of an EFCS system computer.
Readers interested in the subject may wish to read
the paper titled “The importance of the pre-flight
Flight Control Check” published in issue #01, dated
January 2005, of this magazine.
Safety First
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# 06 July 2008
The Airbus Safety Magazine
2 Spoiler fault capture
The aircraft was dispatched with a LH spoiler
actuator #5 in faulty condition.
When the crew taxied the airplane, the spoiler
anomaly was captured during the pre-flight control
checks.
The crew performed roll inputs with the sidesticks
and the SEC detected the lack of response of LH
spoiler 5 by monitoring the difference between the
order given and the position of the spoiler. The
EFCS computer SEC2, that controls spoilers 5,
disabled the two spoilers 5 as a pair.
F/CTL SPOILER FAULT was triggered, and spoiler
shown as FAULT RETRACTED (5) on the ECAM
F/CTL page.
Figure 1 illustrates the messages displayed on the
F/CTL page of their ECAM.
5
5
Full left
F/CTL SPOILER FAULT
5
5
Full right
Figure 1: Spoiler 5 fault during F/CTL check
12
3 SEC reset
The crew reset the SEC in an attempt to recover
control of spoilers 5.
As a result, ECAM indications went back to normal,
i.e. F/CTL SPOILER FAULT cleared and spoilers
5 were displayed back to GREEN on the F/CTL
page (fig.2).
Figure 2: All GREEN after SEC reset
Considering that the systems status was back to normal, the crew then resumed the flight sequence.
4 Consequence
of the SEC reset
Through the SEC reset, the monitoring system of
the spoilers was reinitialized and this cleared the
fault message. The faulty condition, however,
remained.
The capture by the monitoring system, based on
the difference between given order and position
of the flight control, would have required a second
flight control check.
Had the crew performed a new flight controls check
after the SEC reset, the same spoiler fault ECAM
warning would have popped up again.
As the flight resumed, aerodynamic forces
extended the faulty LH spoiler, forcing the flight
crew to counteract the LH roll tendency.
The ECAM warning SPOILER FAULT did not
appear during the take-off run, nor during the early
climb, as it is inhibited in phases 3 to 5 (from takeoff thrust application to 1 500 feet.
Once in level flight, recordings indicate that about
4° of RH rudder trim was necessary to compensate
for the uncommanded spoiler extension. The crew
was able to fly to its original destination.
Safety First
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# 06 July 2008
The Airbus Safety Magazine
5 FCOM
improvement
In order to stress the need to perform a Flight
Control Check after the resetting on ground of the
EFCS, it was decided to add a note in the “ELAC
or SEC malfunction” part of the 3.04.24 Computer
Reset Table (P5).
On the A320 family program, TR reference 105-1
was issued in June 2007 (fig. 3).
A similar TR reference 568-1 was issued for the
QRH 2.38.
ELAC or SEC malfunction
27
ELAC or SEC
These TR have been incorporated in the June 2008
revisions (REV 42) of the A320 family FCOM and
QRH.
On the A310/A300-600 and A330/340 programs
the note had already been incorporated in their
respective FCOM and QRH.
On the A310/300-600, the note concerns the
EFCU reset, which controls the spoilers electrically.
Note: The A380 is, as of today, not concerned
by this issue, as FCTL system resets are
not authorized.
WARNING :
Do not reset more than one computer at a time.
. It is possible to reset flight control computers in
flight, event if not requested by the ECAM,
provided only one reset is performed at a time:
For the ELAC only, in case of uncommanded
maneuvers during the flight, it is not
recommended to reset the ELAC.
Note : . When an ELAC reset is performed
on ground the crew must check
the pitch trim position.
. If a reset is performed on ground,
the flight crew must then perform
a flight control check, as per SOP.
Figure 3:
Extract of TR 105-1
6 Conclusions
This incident, fortunately, did not have any major
operational consequence.
It illustrates, however, the message that the authors
wish to highlight:
If a reset of an EFCS or EFCU computer
is performed on ground, it must be
followed by a flight control check
Airbus wishes to thank Kristjof Tritschler and
Germanwings for their contribution to this article.
14
A320/ Possible
consequences
of VMO/MMO
exceedance
By: Michel PALOMEQUE
A320 Flight Safety Director & Chief Engineer Advisor
A320 Program
1 Introduction
This article is a follow up on a presentation given
at the last Flight Safety Conference in Barcelona
on October 2007.
It describes the solutions, which have been
developed and implemented in the latest ELAC
L84 and L93 software standards in order to assist
the crews in avoiding large altitude incursions linked
to VMO/MMO exceedance scenarios.
It will describe as well the modifications brought
to the last standards of the Flight Warning Computer
In order to improve pilot awareness in case of Auto
Pilot disconnection.
2 Description of two
possible scenarios
VMO/MMO exceedance events usually happen
in cruise or during descent, when the aircraft
encounters a significant wind gradient.
The aircraft typically has the Auto Pilot engaged,
and the wind gradient will lead it to exceed the
High Speed protection (HSP) threshold (the speed
or Mach number at which the HSP activates
depend on the flight conditions, but do not exceed
VMO+6kt or MMO+0.015).The triggering of the
HSP will automatically disconnect the Auto Pilot.
2.1 First scenario : no pilot input
following AP disconnection
If the side stick is free, HSP activation will automatically add a small positive G demand until the
aircraft returns within the flight envelope.
From experience, the altitude excursion is limited
to less than 700 ft (fig. 1).
2.2 Second scenario : strong pilot input
following AP disconnection
If the pilot reacts to the over speed by pulling too
strongly on the side stick (in which case the pilot
input will be added to the HSP input), the Angle
Of Attack (AOA) protection may be triggered.
This means that he aircraft will climb at the highest
AOA value for as long as the protection is activated.
Since deactivation may only be achieved through
nose down side stick input, simply releasing the
stick will not stop the climb.
Delayed reaction from pilots in applying forward
stick input results in large altitude excursions (fig. 2).
Safety First
The Airbus Safety Magazine
Moderate
AP reaction
HSP
activation
Wind
gradient
• AP disconnects
Concurrently, a NOSE
UP G demand is
automatically added until
the aircraft returns in the
normal flight envelope.
Altitude increase
(reports up to
+700ft)
Figure 1: IF STICK FREE after HSP activates
and AP disconnects,the A/C will slightly
overshoot VMO/MMO and fly back
within the envelope
Wind
gradient
Wind
gradient
AoA
AoA
activation
activation
HSP
HSP
activation
activation
Figure 2: IF STRONG PITCH UP STICK INPUTS
after HSP activates and AP disconnects,
the AoA protection may also activate.
Simply releasing the stick will not stop
the climb. Forward stick input is needed
to deactivate the AoA protection.
15
# 06 July 2008
16
3 HSP activation/
AP disconnection
logics change
implemented in
ELAC L84 and L93
3.2 New Mach threshold for HSP
activation/AP disconnection
L83/L91
standards
A319/
A320
L84/L93
standards
M. 83
M.83
As indicated above, HSP activation disconnects
the AP.
(3 second
filter)
A318/
A3211
M.86
Flight Path Angle
dependant MMO
threshold + 0.01
(3 second filter)
(no filter)
In order to avoid the above type of scenario, it
was decided to:
• Introduce a 3 second filter to avoid AP
disconnection in case of very short overspeed
situations
• Increase the HSP activation threshold so as to
keep the benefit of the Auto Pilot at higher speeds
and Mach numbers.
In the L84/L93 standards, the Mach threshold is a
function of the Flight Path Angle and is identical for
the whole A320 family. The main aim is to have a
better protection of the aircraft during cruise (fig. 3).
MMO threshold
(Mach number)
3.1 New speed threshold for HSP
activation/AP disconnection
L83/L91 standards
L84/L93 standards
356 kt
365 kt (3 second filter)
0.85
0.84
0.83
0.82
In the L84/L93 standards, a 3 second filter has
been introduced and the speed threshold has been
increased by 9 kt.
0.81
-3°
-2°
-1°
0°
Flight path angle (degrees)
Figure 3: L84/L93 Mach threshold for HSP
activation/AP disconnection.
1
2
ELAC hardware
ELAC software
Mod. number
Service Bulletin
A or A’
L84 standard
381052
Not yet available
B
L93 standard
380082
27-1182
This L83/L91 standards logic is limited to the A318/A321 because of A319/A321 compability issues with previous standards
Activation of VMO/MMO protection function through hard pin program Mod. n° 38298, SB n° 27-1183
Safety First
17
# 06 July 2008
The Airbus Safety Magazine
4 AP disconnection
unawareness
With the old FWC standards, the VMO/MMO
OVERSPEED aural warning (continuous repetitive
chime) may superseed the AP disconnection aural
warning (cavalry charge).
The overspeed warning is activated at VMO+4kt
or MMO+0.006 i.e. before the activation of the
HSP, and hence disconnection of the AP
The following has been reported: upon activation
of the VMO/MMO OVERSPEED warning, a crew
member had pressed the Master Warning
pushbutton, thereby cancelling the AP disconnection aural warning, even though it had not yet
been generated (since it was superseded by the
overspeed warning).This may lead to situations
where the pilots are unaware of the AP
disconnection.
Note: AP disconnection will lead as well to the
generation of an AUTO FLT AP OFF alert
message on the ECAM, which cannot be
cleared through the Master Warning
pushbutton.
The logics for the cancellation of the VMO/MMO
OVERSPEED and AP disconnection warnings are
as follows :
• VMO/MMO Overspeed warning cancellation:
– Whatever the FWC standard, a Continuous
Repetitive Chime (CRC) cannot be cleared by
an action on the Master Warning P/B.
• AP disconnection caution cancellation:
– Old FWC standards (H1E2, H2E2):
The Cavalry charge may be cancelled by an
action on the Master Warning even if not yet
generated (hidden by CRC).
– Newer FWC standards (H1E3, H2E3, H2E4,
H2F2, H2F3 ):
The cavalry charge can only be cancelled if
generated.
5 Conclusion
In order to avoid significant altitude excursions
and AP disconnection unawareness in case of
VMO/MMO exceedance, Airbus recommends
installation of :
• Standards L84 or L93 of the ELAC
• Standards H1E3 or H2E3, H2E4, H2F2, H2F3
of the FWC.
18
A320/
Prevention
of tailstrikes
By: Michel PALOMEQUE
A320 Flight Safety Director & Chief Engineer Advisor
A320 Program
1 Introduction
Like the preceding paper on VMO/MMO exceedance, this article is a follow up on the presentation
titled “A320 ELAC” given at the last Flight Safety
Conference in Barcelona on October 2007.
It will look as well at the safety improvements
brought to the ELAC in the form of the latest
L84 and L93 standards, which bring additional
prevention means against tailstrikes during landing.
Two other modifications will also be described,
concerning the pilot awareness of a too high pitch
in the landing phase.
Pitch attitude limit
with MLG fully compressed
Pitch attitude limit
with MLG fully extended
2 Description of typical
tailstrike scenario
Most of the tailstrikes on A320 family aircraft occur
during landing in manual mode (Auto Pilot OFF),
when the sidestick is maintained in the aft position
after touch down (Fig1).
The importance of this subject is obviously
correlated to the fuselage length. It is, therefore,
particularly important to A320 and A321 operators.
A318
A319
A320
A321
15.7°
13.9°
11.7°
9.7°
17.3°
15.5°
13.5°
11.2°
Safety First
The Airbus Safety Magazine
Normal
law
Flare law
Tailstrike
Ground law
Ground spoilers
deflection
50 ft
20 ft to 30 ft
Touch down
n
Thrust levers
set to idle
Flare
A/C on the ground for
5s and - θ <2.5°
AFT
Stick
FWD
Stick
Pitch sidestick orders
Figure 1: Normal landing with sidestick
maintained AFT after the touch down.
3 Flight control law
improvement
In order to avoid the above scenario, it was decided
to improve the flare law of the flight control law of
the A320 and A321. This was done by introducing
a limitation of the side stick nose up inputs during
landing.
Full Up
Pitch attitude commanded (deg)
18
16
-16
-2
Sidestick
deflection
(deg)
3.1 Flare law before L84 and L93
standards
The principle is as follows:
• A pitch sidestick deflection corresponds to a
commanded pitch attitude.
• The maximum commanded pitch attitude with
full back stick is 18 degrees (fig. 2).
Figure 2: Flare law
before L84 and L93
standards
-22
Full Down
19
# 06 July 2008
20
3.2 Flare law in L84 and L93 standards
With the new law introduced in the latest ELAC standards (fig. 3), the maximum commanded pitch
attitude on ground is limited to the values indicated in the table below:
Pitch rate change
< 3°/s
>3°/s
A320
9°
6°
A321
7°
4°
Full Up
Pitch attitude commanded (deg)
18
7 (Max limitation: pitch rate <0)
4 (Max limitation: pitch rate >3%)
This limitation is triggered by the ground spoiler
extension, thus ensuring that it will be active only
during landing. It is therefore deactivated during
the take off and go-around phases.
Simulations with the improved control laws have
confirmed the following:
• No impact on the landing performance
• The usual flare is not modified
• No interference in case of go-around or during
take off due to the ground spoiler condition
16
-16
-7.2 -4.8
-2
Sidestick
deflection
(deg)
-22
Full Down
Figure 3: A321 pitch
attitude control law
on ground
ELAC hardware
ELAC software
Mod. number
Service Bulletin
A or A’
L84 standard
38105
Not yet available
B
L93 standard
38008
27-1182
Safety First
21
# 06 July 2008
The Airbus Safety Magazine
4 Additional alerts
to impeding tailstrike
In order to further increase pilot awareness to an
impeding tailstrike, the following modifications have
been developed for the A320 and A321:
• A pitch limit indicator on the Primary Flight Display,
which is displayed at landing (below 400 feet
AGL in both manual and automatic modes)
when the thrust levers are below the FLEX/MCT
setting.
Pitch limit indicator
on PFD
“Pitch, Pitch”
audio call-out
Note: due to the below FLEX/MCT condition,
the pitch limit indicator is not displayed
during the T/O phase.
(This modification is available only
for aircraft with the EIS2 standard)
• A “PITCH, PITCH” call out, activated when the
pitch is greater than a certain threshold and if
TOGA is not selected.
(The call out is available on the following
standards : FWC H2F3 or H2F3P and FAC 618
or 619).
Mod. number
Service Bulletin
Activation
(only on A320/A321)
37444
No std SB
RFC/RMO process
EIS2 S7 standard
36725
31-1276 or 31-1271
Activation
(only on A320/A321)
37445
FAC 618 standard
619 standard
FWC H2F3 standard
H2F3P standard
35522
36766
35220
38425
No std SB
RFC/RMO process
22-1226
22-1226
31-1267
31-1300
5 Conclusion
In order to avoid excessive pitch up demand at
landing when on ground, the ELAC flight control
laws have been enhanced in the new ELAC L84
and L93 standards.
Associated to this modification, a pitch limit indicator
on the PFD and a “PITCH, PITCH” call out have
been developed, to further increase pilot awareness.
We are confident that these modifications will help
to minimize the number of tailstrikes during landing.
22
Low fuel
situations
awareness
By: Frédéric MARANI
Manager, Safety Strategy Development
Product Integrity
1 Introduction
One easily understands that lack of fuel may
seriously impair the safety of a flight.
Monitoring the fuel status all along a mission is
therefore one of the critical tasks of the crew. The
challenge of this monitoring is that fuel status may
be adversely affected by a very wide variety of factors.
This article will briefly review the factors affecting
fuel status, and will then stress :
• The importance of fuel checks, developed to
ensure timely detection of a low fuel situation
• The limits in the use of the FMS in Fuel On Board
projections under degraded conditions
This article is a complement to the presentation
titled “Detecting and managing situations of low
usable fuel” given during the 14th Flight Safety
Conference in Barcelona on October 2007.
2 Fuel status variables
The factors affecting the fuel status may be sorted
out in two classes.
• Those linked with the operating context such as :
- Delays induced by ground operations factors
at departure airport
- Air Traffic Control constraints modifying the
scheduled flight plan
- Meteorological factors
- Congestion at the destination airport leading
to holding or diverting.
• And those linked with the aircraft like :
- Airplane ageing: mainly the engines, but also
the airframe and nacelles
- Airplane flying under conditions of the Minimum
Equipment List (MEL) or Configuration Deviation
List (CDL)
- Aircraft speed not in accordance with the
scheduled flight plan
- Overweight compared to flight plan
but also
- In-flight failures with an effect on fuel
consumption
- In-flight failures with an effect on the fuel available
for the mission (e.g. fuel leaks leading to fuel
being trapped).
3 Standard Operating
Procedures (SOPs)
Because of the variety of causes that may lead to
a low fuel situation, and in view of the configuration
of the fuel system, several means must be used
to maximise the chance of an early detection.
Safety First
23
# 06 July 2008
The Airbus Safety Magazine
According to the SOPs for the cruise phase,
3 types of check have to be performed when
over flying a waypoint, or every 30 minutes:
1. Fuel On Board
2. FMS Fuel prediction
3. Fuel On Board/Fuel Used
The above checks need to be performed as well
each time a FUEL IMBALANCE procedure is
necessary, and they should be performed before
applying the Fuel Imbalance procedure.
Note: On the A300-600/A310/A320family/
A330/A340 and A380 aircraft, FUEL
IMBALANCE detection is available as an
“advisory” message associated with the
Fuel System page on the System Display.
On the A340-500/600 and A380, it
triggers as well an amber caution
appearing on the ECAM.
No such alarm is available on the A320
family for the time being.
3.1 First check: Fuel On Board
Cruise SOP FCOM 3.03.15 P1 (SA/LR) FCOM
2.03.15 P1 (WB)1 :
“Check Fuel on Board (ECAM)… and compare
with the computer flight plan or the FCOM
In-Cruise Quick-Check Table.”
Any marked difference in FOB quantity compared
to the flight plan prediction may reveal either:
• A fuel over-burn, which may be explained by:
- Some significant deviations from the initial flight
plan, due for instance to restrictions from Air
Traffic Control, degradations of meteorological
conditions, engine failure
- An airplane configuration degradation, due for
instance to an aerodynamic drag increase
coming from flight control surfaces permanently
deflected, a landing gear or gear doors partially
extended, ice accretion.
• An external fuel leakage
FOBBLOCK
Taxi fuel
Suspect a fuel over burn or a fuel leak
whenever FOB differs from FOB flight plan
nominal
Trip fuel
with fuel failure
SOP fuel
checks
Start of fuel
leak or over
burn
Contingency fuel
Alternate fuel
Final reserve fuel
Emergency fuel situation
Destination Alternate
SA: Single Aisle : A318/A319/A320/A321
LR: Long Range : A330/A340
WB: Wide Body : A300/A310
1
Time
24
3.2 Second check:
FMS Fuel prediction
Important note:
Cruise SOP FCOM 3.03.15 P1 (SA/LR) FCOM
2.03.15 P1 (WB):
“Check… fuel prediction (FMGC) and compare to
the computer flight plan or the FCOM In-Cruise
Quick-Check Table.”
The FMS is able to make FOB predictions at point
along the flight plan: waypoints, destination (DEST
EFOB) or alternates. It considers the entered flight
plan and assumes a nominal aircraft (potentially
customized to monitored performance level through
individual PERF factor) i.e. without failure.
It is updated permanently from the measured FOB
and from modifications of the flight plan entered
into the FMS, if any. In nominal conditions, without
flight plan update, DEST EFOB should not show
any marked evolution throughout the flight.
Hence, in case of fuel over-burn due, for instance,
to a drag increase, DEST EFOB will decrease
permanently at the same rate the actual FOB is
drifting away from the initial flight plan prediction.
The same behaviour would happen for a fuel leak.
FMS prediction is a projection of
actual FOB that never takes into
account any degraded state of the
aircraft, even when due to a failure
that is monitored and shown on the
cockpit panel or ECAM displays.
This rule has only one exception:
engine failure, once confirmed in the
FMS.
Decreasing DEST EFOB indication is a sign of
degrading fuel situation.
For the above-mentioned reasons, it also means
that the displayed DEST EFOB value cannot be
used to anticipate the fuel status at destination.
The same is true for all other EFOB projections,
like at waypoints or alternates.
Note: DEST EFOB displayed on FMS pages
turn to amber if it becomes lower than
the sum of Alternate and Final reserves
fuel entered in the FMS: it indicates that
contingency fuel and extra fuel reserves
are no more available.
FOB
FOBBLOCK
Suspect a fuel over burn or a fuel leak
whenever FMS EFOB decreases
after then
do not use EFOB value for validating flight strategy
MIN DEST EFOB =
nominal
with fuel failure
Contingency fuel
Alternate fuel
Final reserve
fuel
ALTERNATE FUEL
+
FINAL RESERVE FUEL
MIN DEST EFOB
FMS DEST EFOB
Emergency fuel situation
Destination Alternate
Time
Safety First
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# 06 July 2008
The Airbus Safety Magazine
Important note:
3.3 Third check:
Fuel On Board/Fuel Used
A fuel leak downstream of the Flow
Meter will not be detected through
this check. It will, however, be
revealed through an excessive fuel
flow on one of the engines.
Cruise SOP FCOM 3.03.15 P1 (SA/LR) FCOM
2.03.15 P1 (WB):
”Check that the sum of the Fuel On Board and the
Fuel Used is consistent with the Fuel On Board at
departure… If the sum is either unusually smaller
than the FOB at departure, or if it decreases,
suspect a fuel leak.”
Indeed, an unexpected engine fuel flow level may
be caused by:
• A fuel leak, downstream of the Flow Meter,
sometimes confirmed by:
- Fuel spray visible from the cabin coming from
engine or pylon
- Fuel smell in the cabin
• But also a fuel over-burn associated with a failure
impacting the aircraft aerodynamics or engine
performance with the following possible
indications:
- Step or steep increase of engine control
parameter
- Difficulty to maintain ceiling or Mach number
- Time or distance increase during step climbs
- Aircraft asymmetry along roll or yaw axis visible
sometimes only through compensation by
control surfaces
- Noise, buffet vibrations.
A higher sum may provide the indication of a frozen
fuel quantity parameter leading to a wrong FOB data.
Note: The amber caution F. USED/FOB
DISAGREE exists basically on the A340500/600 and A380.
On the A330 and A340-200/300, they
have to be activated, provided the aircraft
are equipped with the following minimum
standards: FCMC 9.0 and FWC K5-5
(A330) or L8-0 (A340).
This caution does not replace the SOP
check, but may allow an earlier detection
of a fuel leak.
Fuel
FOB BLOCK
FOB + FU: nominal
FOB + FU: with fuel failure
FU
FU
Suspect a fuel leak whenever
FOB+FU differs from FOB BLOCK
FOB: nominal
Trip fuel
FOB
with fuel failure
SOP fuel
checks
Start of fuel
leak or over
burn
Contingency fuel
Alternate fuel
Final reserve fuel
Emergency fuel situation
Destination Alternate
Time
26
4 Fuel On Board
versus available fuel
The three checks described above all assume that
the FOB is available to fly the aircraft. This may
not always be the case as some fuel may be
trapped or transferring too slowly due to an anomaly
in the transfer sequence such as :
• Non operating transfer device (blocked or clogged
transfer valve etc…)
• Ruptured or cracked transfer line in a fuel tank.
These situations may be detected through :
• A faulty equipment message on the Fuel page
of the System Display
• A developing fuel imbalance when one of the
wing tanks is affected
• A deviation in the fuel transfer sequence.
5 Conclusion
The FOB, Fuel prediction and FOB/FU checks in
cruise provide powerful means for detecting an
abnormal fuel situation. These checks, included
in the cruise phase SOPs, should be adhered to
without exceeding the indicated interval of 30
minutes.
These checks should be performed as well after
detection of an abnormal fuel status.
They will allow, after the corrective measures have
been taken, to ensure that the procedures applied
have reached the expected results.
It is also important to bear in mind that:
• FMS EFOB predictions do not take into account
non-nominal aircraft conditions (except engine
failures once confirmed in the FMS) and have to
be corrected to take into account the
consequences of excessive fuel consumption
or fuel leaks.
• FOB/FU checks will not detect fuel leaks or
excessive fuel burn downstream of the Flow
Meter and should therefore be complemented
by engine fuel flow checks.
With the rising price of fuel, there is a high chance
for extra fuel reserves to be more and more
challenged: in this evolving context, it is certainly
worth developing crew awareness in terms of fuel
monitoring to maintain a high level of safety in
aircraft operation.
Safety First
27
# 06 July 2008
The Airbus Safety Magazine
Rudder
Pedal Jam
By: Joan RENDU
Senior Engineer, Flight Control Systems
Customer Services
2 Original rudder pedal
protective cover
1 Introduction
In 1998, two A340 operators reported that when
performing a rudder travel check, pedal displacement was found to be rough. Investigation
evidenced that pens were stuck in the rudder pedal
mechanism. These objects had fallen down from
the cockpit through the cutouts of the cockpit
pedals assembly covers. This led Airbus to develop
a device to prevent such occurrences on the
A330/340 and A320 family of aircraft.
In view of the remaining number of aircraft flying
without this modification, it seems worthwhile to
remind operators about the existing modifications.
The original cockpit pedals assembly covers
presented a 5 cm open gap, to allow free movement of the rod connecting the pedal to the brake
mechanism.
This unprotected gap let objects like pens or
calculators slip into the braking mechanism.
GAP
Protective cover
with no brush
28
3 Modified rudder
pedal cover
The first events were reported on A340 aircraft
and new pedal covers with brush were developed
for the A330/340 family. Due to similarity in design,
a similar cover was introduced on the A320 family
as well.
Protective
cover fitted
with brush
Detail of brush
4 New case reported
Recently one operator reported an event on an
A320 aircraft.
The report indicates that, during preflight, the rudder
pedal felt jammed. Investigations showed this was
again due to a foreign object located into the pedal
mechanism. The aircraft was pre-mod and the
service bulletin was not embodied.
5 Conclusion
Following this latest event and in order to prevent
objects from falling into the pedal mechanism, Airbus
would like to promote the following modifications:
A330
Modification n° 47292 fitted in production on aircraft
models A330-200 from MSN 0339 and on models
-300 from MSN 0342
Service bulletin n° 27-3074
A340
Modification n° 47292 fitted in production from
MSN 0335
Service bulletin n° 27-4080
A318
Fitted on all aircraft
A319/320/321
Modification n° 28555 fitted in production from
MSN 1344/1334/1356 respectively
Service bulletin n° 27-1131
The title of SB 27-1131, which is currently “Rudder
mechanical control introduce modified rudder pedal
mechanism assembly” will be changed to a more
precise title “Introduce a means to prevent foreign
object falling in rudder pedal mechanism assembly”,
and an OIT will be issued to inform operators.
Safety First
29
# 06 July 2008
The Airbus Safety Magazine
Why do certain
AMM tasks require
equipment resets?
By: Duncan HARRIS
Flight Guidance and
Navigation Systems Engineer
Customer Services
1 Introduction
While Line Replaceable Unit (LRU) replacement is
often performed under significant pressure to
maintain a timely aircraft departure, the relevant
Aircraft Maintenance Manual (AMM) should not be
forgotten. This article looks at one aspect of those
AMM procedures whose importance may not
always be entirely understood.
While the AMM may not always explicitly require
a reset, this can be accomplished by an OFF/ON
action request. For example, when starting a task,
it may simply require switching OFF certain LRUs.
This is accomplished either by pulling the relevant
Circuit Breaker or by Cockpit Push Button. At the
end of the task, when returning the aircraft to
original configuration, the operator is required to
switch the LRU back ON. A reset is effectively
performed by the OFF/ON action. The LRU may
also be switched OFF to avoid electrical or data
disturbances in the affected system.
2 Why do certain
AMM tasks require
equipment resets?
The reset is often necessary to clear faults recorded by systems before or even possibly during
maintenance. Some systems (the example below
illustrates this) use fault latching mechanisms. That
is to say that once a fault has been detected, the
input system will be considered unavailable until
the user system is next reset.
LRU#1 provides input
data to LRU#2
LR
U#
1
Input System
LRU#2 may consider LRU#1
failed if it sends corrupt/inconsistent
data or no data at all
LR
U#
2
Monitoring/User System
Typically if maintenance actions are performed to
correct a given fault, it can be necessary to reset
user systems to ensure that they consider the input
system operational again.
30
3 An example of Air
Data/Inertial
Reference Unit
(ADIRU) replacement
previous flight. In addition it detected that the
ADR#3 was INOP. Without ADR#1 or #3, only
ADR#2 was considered available. Under these
conditions the Electronic Flight Control system is
only capable of operating in Alternate Law.
ADIRU#1 Latched
Failed by ELACs
Airbus recently investigated an event in which it
was found that an aircraft departed in Alternate
Flight control law following maintenance actions
not performed fully according to AMM procedure.
The circumstances of this event were as follows:
During flight an ADR#1 (Air Data Reference) fault
was detected. The ELAC (Elevator and Aileron
Computer) on detecting this fault, latched the
ADR#1 as failed until its next reset. The ELAC
subsequently used only ADR#2 and #3 data for
calculations.
#1
U
ADIR
EL
ADIRU#1 INOP
as per MMEL
AC
U#1
ADIR
U#2
U#3
ADIR
AC
#1
#3
#1
U
ADIR
EL
AC
#2
ADIR
Both ELACs monitor
data sent from all
three ADIRUs. Any
ADIRU found to be
faulty or sending
discrepant data
when compared to
the other ADIRUs is
latched failed until
next ELAC reset
EL
#2
U
ADIR
EL
AC
#2
Upon landing, the maintenance crew swapped
ADIRU#1 and #3, consequently the faulty
ADIRU#1 became ADIRU#3. ADIRU#3 was
therefore placed INOP as per MEL and the aircraft
dispatched. At no point was an ELAC & SEC reset
or aircraft electrical power reset performed.
The consequence of this was significant: the ELAC
kept its memory of ADR#1 Fault latched from the
Had the maintenance crew correctly followed the
AMM, including the ELAC reset, then the ADR#1
fault latched by the ELAC would have been reset
and the Alternate law condition avoided.
5 Conclusion
• Remember to always follow the relevant AMM
task, even if each step may not always appear
necessary.
• If in any doubt:
- Contact Airbus customer support to task for
assistance.
- Perform an electrical reset of the aircraft: cut
all aircraft electrical power, wait 5 minutes, and
then power up again.
Safety First
31
# 06 July 2008
The Airbus Safety Magazine
Slide/Raft
Improvement
By: Fabien SAUVAGE
Emergency Equipment Engineer
Customer Services
1 Introduction
For years Airbus has been encouraging operators
to report all escape slide and slide raft deployments,
whether scheduled or inadvertent, successful or
unsuccessful, in order to improve their reliability.
The number of reportings, however, has steadily
decreased and represents only a fraction of the
estimated number of deployments.The purpose
of this article is to draw attention to the need for
regular and extensive feed back of slide deployment
information to Airbus.
2 Regulatory
requirements
Every 36 months, operators have to perform a
certain number of slide deployments, which is a
function of the number of doors on the considered
type of aircraft, irrespective of the fleet size.
A330/A340 fleets can be combined for common
doors, therefore an operator equipped with a mix
of A330/A340 will have to deploy 4 slides, as this
type of aircraft is equipped with 4 doors per side
(5 on the A340-600).
These deployment may be performed on either
side and do not all have to be performed on the
same aircraft. Inadvertant deployments may not
be used to satisfy these requirements.
32
3 Product
improvement
Based on the above requirements, Airbus has
estimated that on the A330/A340 familly alone,
approximately 140 deployments should have been
performed in 2007. Only 14, however, have been
reported to Airbus, of which 7 were successful.
Slide reliability is increasing every year because
of the continuous system and component
improvements and thanks to the input from our
customer airlines. Exhaustive deployment reporting
is key to a better overview of the slide and slide
raft reliability, and allows to identify areas that could
be improved. Close monitoring and reporting of
in-service occurrences is essential for an efficient
event analysis and associated engineering
investigation/resolution launch.
4 Recommendations
The Aircraft Maintenance Manual and SIL 25-124
specify how deployment tests should be performed.
The last page of SIL 25-061 Rev 3 includes a
slide/raft deployment reporting form to be forwarded
to Airbus Customer Services.
5 Conclusion
In order to be able to improve the slide/rafts
reliability, and hence passenger safety, we
do encourage the reporting of all
deployments, whether successful or
unsuccessful, scheduled or inadvertent.
Safety First
33
# 06 July 2008
The Airbus Safety Magazine
Cabin
attendant falling
through the avionics bay
access panel in cockpit
By: Per-Oliver GUENZEL
Flight Safety Advisor
A330/A340 program
1 Introduction
2 Avionics bay access
hatch
Airbus has received reports of cabin attendants falling
through the avionics hatch door located in the cockpit,
when it is open for maintenance purposes. In most
of the cases the cabin attendant hurt him/herself
only slightly and could continue his/her duty. But
there were also some occurrences where the cabin
attendant couldn’t continue his/her duty.
In 2001, an OIT (ref.: AI/SE 999.0002/01) was
published to inform operators about such events
and to provide some general recommendations.
In addition, Airbus has developed a device that
should contribute to prevent such mishaps.
The avionics compartment access hatch is located
in the cockpit behind the captain’s seat.
It opens upwards from front to back. When the
hatch is open, it rests vertically and covers
approximately 80% of the corridor width. This
makes the hatch position noticeable and requires
care to be taken to move around it when entering
the cockpit. Therefore anyone entering the cockpit
while the hatch is open should notice it (see fig. 1
and 2).
Figure 1: Open access hatch seen from cockpit door
(prototype of protective arm shown)
Figure 2: Open access hatch seen from behind
the first officer’s seat
34
The reports received by Airbus about a cabin
attendant falling into the hatch are not very detailed,
but usually the cabin attendant entered the cockpit
to provide some beverage to the flight crew, he/she
stepped in the open hatch not realizing that there
was a “hole” or fell in when stepping backwards
to leave the cockpit.
Airbus decided to develop a protective device to
help airlines prevent such events.
3 Avionics bay access
hatch protective arm
Mechanics need to have easy access to the avionics
bay from the cockpit, sometimes with electronics
equipment, thus it was necessary to develop a
“protection” that doesn’t interfere with the
mechanics work area. This “protection” had to be
easily retrofittable, act as a visual attention getter
to warn those who don’t realize the “hole” in front
of them and provide enough physical resistance
to somebody stepping back against it. However,
its intent is not to act as a solid barrier to prevent
somebody from falling.
The best compromise found by Airbus engineers
is a protective arm that is attached to the hatch
and unfolded when the hatch is open (see fig 3 & 4).
Figure 3: Avionics access hatch with folded
protective arm
Figure 4: Avionics access hatch with unfolded
protective arm
The following SBs are available to retrofit an avionics
compartment access hatch with a protective arm
on the different aircraft series.
A330–200/-300: SB 25-3356
A340-200/-300: SB 25-4292
A340-500/-600: SB 25-5146
The estimated installation time of the SB is 3 hours.
The same modification is available as an option
for production a/c.
Safety First
Subscription form
# 04 June 2007
SAFETY FIRST - The Airbus Safety Magazine
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