content - Belgian Cockpit Association

Safety
Edition January 2012
CONTENT:
q A320 Family / A330 Prevention
and Handling of Dual Bleed Loss
q The Fuel Penalty Factor
q The Airbus TCAS
Alert Prevention (TCAP)
q A380: Development of the
Flight Controls - Part 1
q Facing the Reality of Everyday
Maintenance Operations
Issue
13
The Airbus Safety Magazine
2
Safety
Issue 13 | January 2012
The Airbus Safety Magazine
Issue 13 | January 2012
Yannick MALINGE
Chief Product Safety Officer
Safety First
Editorial
The Airbus Safety Magazine
Sometimes it is useful to try to stand back from the daily business and
reflect on our industry and the collective safety efforts of the many
people who continue to work so hard to improve the safety situation.
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.
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.
Safety
Edition January 2012
CONTENT:
q A320 Family / A330 Prevention
and Handling of Dual Bleed Loss
q The Fuel Penalty Factor
q The Airbus TCAS Alert
Prevention (TCAP)
q A380: Development of the
Flight Controls - Part 1
q Facing the Reality of Everyday
Maintenance Operations
q Safety Benefits of PBN RNP
and RNP AR Approaches
The Airbus Safety Magazine
A320
Close up on
new A320
sharklet
All articles in Safety First are presented for ­information only and are not
intended to replace ICAO guidelines,
standards or recommended practices,
operator-mandated 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.
Articles may be reprinted without
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acknowledgement to Airbus. Where
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reflect the views of Airbus, neither
do they indicate Company policy.
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
Product Safety department (GS)
1, rond point Maurice Bellonte
31707 Blagnac Cedex - France
Contact: Nils FAYAUD
E-mail: nils.fayaud@airbus.com
Fax: +33(0)5 61 93 44 29
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Issue
13
Safety First, #13 January 2012. Safety First
is published by Airbus S.A.S. - 1, rond point
Maurice Bellonte - 31707 Blagnac Cedex/France.
Editor: Yannick Malinge, Chief Product Safety
Officer, Nils Fayaud, Director Product Safety
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This Brochure contains sensitive information that is correct at the time of going to press.
Despite our continued focus on accidents to identify safety lessons, it
is also useful to study some examples of very challenging situations
with positive outcomes, and by so doing we can get clues about the type
of behaviours and skills that can achieve success from all threatening
situations. Three events come immediately to mind. The amazingly successful landing in Bahgdad of an A300 with a severely damaged aircraft
following on from a missile strike; the A320 emergency landing on the
Hudson River with both engines irreparably damaged by bird strikes;
and finally the successful landing following an uncontained rotor failure
which did unprecedented damage to an A380.
There has been much success but amidst the explosion of media reaction
to a new accident or major incident we tend to forget that the aviation
world today is significantly safer than in times gone by.
However, knowing the dangers of complacency, the challenge remains
for all of us – how do we continue to improve and what approach shall
we take to secure even better levels of safety? The industry is increasingly aware of the need to maintain the required skill and knowledge levels
of the industry professionals. One of the key questions is what are the
basics in today’s environment?
Our 18th Flight safety conference this year will address this key issue.
It will focus on what we in Airbus think are some of the highest priorities. We will take a hard look at the appropriateness of current training
against the evident changes in the background, experience and currency
of today’s aviation people. We also know that for a culture of safety to be
successful it has to be driven and demonstrated from the top in any organization. Only then does it have the chance of reaching down into the
“fabric” of the working place. We will also be looking at data and how
valuable it is to all of us as we try hard to collectively improve safety.
This copy of “Safety First” brings to you a range of topics, some new and
some we have touched on before. I hope that you find them interesting
and stimulating and as always we in Airbus welcome your feedback.
This information involves a number of factors that could change over time, effecting the true public
representation. Airbus assumes no obligation to update any information ­contained in this document or
with respect to the information described herein.
I would like to take this opportunity on behalf of all the Airbus Safety
team in wishing you a happy and safe new year for 2012.
Airbus S.A.S. shall assume no liability for any damage in connection with the use of this Brochure and
of the materials it contains, even if Airbus S.A.S. has been advised of the ­likelihood of such damages.
Yannick MALINGE
Chief Product Safety Officer
Contents
The Airbus Safety Magazine
Information ................................................... 4
A320 Family / A330 Prevention
and Handling of Dual Bleed Loss.................. 5
Xavier JOLIVET / Xavier VILLAIN / Laurent SEGUY
The Fuel Penalty Factor............................... 10
Thomas LEPAGNOT
The Airbus TCAS Alert Prevention (TCAP).. 17
Paule BOTARGUES
A380: Development of ................................ 22
the Flight Controls - Part 1
Claude LELAIE
Facing the Reality of Everyday . ................. 26
Maintenance Operations
Uwe EGGERLING
3
4
Safety
Issue 13 | January 2012
The Airbus Safety Magazine
Issue 13 | January 2012
Nils Fayaud
Xavier JOLIVET
Xavier VILLAIN
Laurent SEGUY
Director Product Safety Information
Director of Flight Safety
Group Manager
A320/A330/A340 Standards
Flight Operations Support
& Services
Group Manager Bleed-Inerting-Fire,
Ice & Rain Protection
Engineering Support
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
As already said, this magazine is a
tool to help share information.
We would appreciate articles from
operators, that we can pass to other
operators through the magazine.
If you have any inputs then please
contact Nils Fayaud at:
On the AirbusWorld website we are
building up more safety information
for you to use.
q In the article “Radio Altimeter
Erroneous Values” published in issue
n°11, the Captain’s FMA illustrated in
fig 5 should have displayed AP1 instead
of AP1+2.
The present and ­previous ­issues of
Safety First can be accessed to in the
Flight Operations Community- Safety and ­Operational Materials portal-,
at https://w3.airbusworld.com
q In the article “Airbus New Operational Landing Distances” published
in issue n°12, the fourth paragraph of
chapter 2/ Major Conceptual Changes
should read: “As a result, a runway
that is dispatched to according to the
current factored Actual (instead of
Available) Landing Distances (ALDs)
requirement may, as soon as the aircraft
leaves the ground, become inappropriate according to the OLD.”
Other safety and operational expertise publications, like the Getting to
Grips with…brochures, e-briefings
etc…are regularly released as well
in the Flight Operations Community at the above site.
If you do not yet have access rights,
please contact your IT administrator.
SAVE THE DATE
After an outstanding event in Rome in
March 2011, we are pleased to announce
that the 18th edition of our annual Flight
safety conference will touch down in
Berlin, Germany from March 19th to
22nd 2012.
The Flight safety conference provides
an excellent forum for the exchange
of information between Airbus and its
A320 Family / A330
Prevention and Handling
of Dual Bleed Loss
1. Introduction
Flight Safety
Hotline: +33 (0)6 29 80 86 66
E-mail: account.safety@airbus.com
e-mail: nils.fayaud@airbus.com
fax : +33 (0) 5 61 93 44 29
News
Erratum
Safety Information on the Airbus
websites
Dual Bleed Loss (DBL) may impact flight operations, as it often
results in either in-flight turn back
or emergency descent followed by
flight diversion.
18th
Berlin, 19-22 March 2012
customers. To ensure that we can have
an open dialogue to promote flight safety across the fleet, we are unable to
accept outside parties.
The formal invitations with information
regarding registration, logistics and the
preliminary agenda have been sent out
to our customers in December 2011.
As always, we welcome presentations
from you, the conference is a forum for
everybody to share information.
If you have something that you believe
will benefit other operators and/or Airbus
or if you need additional invitations or
information, please contact Mrs Nuria
Soler at e-mail: nuria.soler@airbus.com
Many of these DBL events could
be avoided by applying currently
available solutions, which include
design modif ications, as well as
maintenance and operational procedures. In-service experience shows
that the introduction of these mitigation measures have led to a clear
decrease in the number of occurrences.
A DBL requires a quick identification of the situation and a rapid
reaction. To simplify the crew’s
task, a new standardized procedure
has been introduced, that covers all
cases of Dual Bleed Loss.
The aim of this article is to:
q Remind maintenance/engineering
personnel and pilots of the existing
solutions and
q Present crews with the new DBL
ECAM/QRH procedure.
Figure 1
Pneumatic system
layout on A330
2. The Bleed System
in a Few Words
The bleed system supplies pressure
and temperature regulated air to the
aircraft systems. The main users are
the air conditioning system, which
ensures air regulation for both
cabin pressurization and temperature, and the wing anti-ice system
(fig. 1).
On the A320 Family and A330,
the regulation of the bleed system
is purely pneumatic and operates
automatically. Under normal oper-
ating conditions, air is taken from
the engines and the flight crew has
no action to perform on the system.
On ground, under normal operation, the APU can supply bleed
air for cabin comfort or for engine
start. In flight, under abnormal
procedure when the engine bleed
systems are no longer available,
the APU bleed can also supply air
for cabin pressurization (below the
APU ceiling).
5
OVERBOARD
PCE
OPV
3.1 A320 Family
Historically, as indicated in the
Safety First article “A320: Avoiding Dual Bleed Loss” published
in issue n°7 (February 2009), the
overwhelming majority of second
bleed losses on the A320 Family
were caused by an overtemperature
condition.
FAV
TO STARTER
VALVE
3.2.1 Bleed Overpressure
HPV
IPCV
FAN
IP
HP
Figure 2
Bleed components
description on
A320 Family
note
The A330 design
principle is similar
to that of the A320.
Note that on the
A330, the TCT and
TLT are respectively referred to
as ThC and ThS.
In contrast to the A320, the main
cause for Dual Bleed Loss on the
A330 is bleed overpressure (ref. C).
GE mounts are particularly affected
by this phenomenon. The two most
common scenarios are as follows:
3000
60
2500
50
2000
40
1500
30
1000
20
500
Solutions avalaible
10
0
2011
2010
2009
2008
2006
2005
0
AIR ENG 1 BLEED FAULT
-ENG 1 BLEED...............OFF
Temperature Regulation
Pressure Regulation
PCE
FAV
TCT
TLT
OPV
PRV
HPV
IPCV
BMC
Pr
Pt
Precooler
Fan Air Valve
Temp. Control Thermostat
Temp. Limitation Thermostat
Overpressure Valve
Pressure Reg. Valve
High Pressure Valve
Intermediate Pressure Check Valve
Bleed Monitoring Computer
Regulated Pressure Transducer
Transfered Pressure Transducer
Figure 4
ECAM AIR ENG 1(2)
BLEED HI TEMP
caution
AIR ENG 2 BLEED HI TEMP
-PACK 1 OR WAI.............OFF
q Pressure overshoot at thrust
increase during takeoff, due to
degraded reactivity of the Pressure
Regulating Valve (PRV). The overpressure peak increases if the takeoff
is performed with the air conditioning packs selected OFF, due to the
no flow (demand) condition (refer to
adjacent notes).
q Erroneous measurement of
Monitoring
70
3.2 A330
PRV
In 2008, Airbus introduced new
maintenance procedures and designed a “Dual Bleed Loss package”
(ref. A). This package includes a
new Temperature Control Thermostat
(TCT), a new Fan Air Valve (FAV)
and a new Temperature Limitation
Thermostat (TLT).
3500
Pr
Pt
pylon
Nacelle
3.1.1 Maintenance and Design
Enhancements
Today, this DBL package equips
more than 70% of the A320 Family
fleet (either from production or by
retrofit) and no reported Dual Bleed
Loss has been due to the failure of
these new components (fig. 3). A
specific retrofit policy has been
offered to support a prompt in-service
implementation. The few DBL events
reported on this upgraded fleet were
due to installation issues, such as
senseline leakage between TCT and
FAV or TCT filter clogging (ref. B).
Temp
TCT TLT
Figure 3
Evolution of A320
Family Dual Bleed
Loss events
80
Number of events
2004
BMC
4000
2003
To aircraft systems
The Flight Warning Computer
(FWC) F6 standard, planned for
certification beginning 2012, will
include a new ECAM AIR ENG 1(2)
BLEED HI TEMP caution that triggers when one engine bleed is OFF
and the temperature of the remaining
engine bleed exceeds 240°C. The
associated ECAM procedure calls
for one pack or the wing anti-ice to
be switched OFF (fig. 4). Embodiment of the FWC F6 standard will
cancel the OEB 40.
90
Fleet size
2002
An early investigation of each single bleed fault is the most efficient action to prevent
a dual bleed fault. This therefore requires a systematic logbook recording to allow
timely troubleshooting of each single bleed fault detected in flight.
4500
100
2001
Any fault in flight reflects an abnormal system behaviour and must be taken into
account, even if cleared by a reset. Proper troubleshooting of the fault is necessary
in order to reduce the probability of reoccurrence.
5000
The Operational Engineering Bulletin (OEB) 40 (former OEB 203/1
issued in March 2010) was introduced to provide recommendations
to monitor the temperature on the
remaining engine bleed in order
to prevent overheat from occurring.
If the temperature increases above
240°C, the flight crew has to
reduce the demand on this bleed
by switching OFF one pack or the
wing anti-ice system.
2000
Dual Bleed Loss events are generally preceded by single bleed fault occurrences.
Recurrent and unsolved single bleed faults increase exposure to Dual Bleed Losses.
3.1.2 Operational improvements
1999
A Dual Bleed Loss situation corresponds to the loss of both engine
bleed air systems. The non availability of the first bleed system may
be triggered by various causes,
including dispatch under MMEL,
and is monitored and investigated as
part of the bleed system reliability.
A single remaining engine bleed
system is capable of supplying all
the bleed functions. Under these circumstances, a fault on this second
system triggers the DBL situation.
The analysis of DBL events is
focused on the loss of the second
engine bleed system.
Importance of Logbook Recording
Issue 13 | January 2012
1998
3. Failure Scenarios
and Mitigations
The Airbus Safety Magazine
2007
Safety
Issue 13 | January 2012
Number of Aircraft
6
regulated pressure (Pr) due to
frozen condensed water in the pressure transducers, leading the Bleed
Monitoring Computer (BMC) to
shut off the affected bleed system.
This failure mode typically occurs
in cruise or at the start of descent after a long cruise period at very low
temperature (Static Air temperature
lower than -60°C).
Operational note
a) The AIR ENG 1(2) BLEED FAULT caution
generally appears when passing 1500ft
as it is inhibited by the Flight Warning
Computer during phase 5.
b) E xposure to this failure mode may
be reduced by taking off with packs
ON. (FCOM PRO-NOR-SOP-Before Takeoff) and by complying with the Standard
Operating Procedure for two-step takeoff
thrust setting (FCOM PRO-NOR-SOPTakeoff).
Engineering note
The closure threshold of the OverPressure Valve (OPV) is being optimized to prevent early closure in
case of PRV pressure overshoot
at takeoff and subsequent loss of
bleed system. The new OPV setting
will be introduced through a VSB to
be released by Q1 2012 (follow-up
through ref. C).
7
Safety
Issue 13 | January 2012
The Airbus Safety Magazine
1000
30
900
27
Fleet size
800
24
Number of events
700
21
600
18
500
15
400
12
300
9
200
6
100
q Thermostat Controller (ThC)
and/or
2011
2010
2008
2007
2006
2005
2004
2003
2002
2001
2000
1999
1998
The overtemperature occurrences are
mainly driven by the ageing of the:
3
0
0
1997
3.2.2 Bleed Overtemperature
Solutions avalaible
2009
The geometry of the pressure
measurement chamber has been
redesigned (improved drainage and
bigger chamber volume) to allow
more robustness. The new part
number ZRA691-00 is installed in
production by MOD 202028 from
MSN 1254. For in-service aircraft
a specific retrofit policy already
applies to aircraft fitted with GE
mounts (ref. D).
Number of Aircraft
8
q Improved maintenance and design
of the Thermostat Controller
A key parameter to maintain an
optimum serviceability of the component is to adjust the interval for
ThC filters cleaning or replacement,
depending on the severity of
the operating environment. Implementation of this preventive maintenance procedure and customization
of the interval are available from
MPD and via specific SIL (ref. B).
The ThC has also been redesigned
with a new clapper/guide material in
order to further improve its reliability.
This improvement is covered by a
Part Number change and is fitted in
production starting at MSN 1274.
For the in-service fleet, the Liebherr
VSB 398-36-05 released in Nov
2011 applies.
q Enhanced Fan Air Valve test
procedures
New functional test procedures
have been developed to allow an
earlier detection of the drift as well
as an easier detection of faulty components. Specific health monitoring
of the FAV is also recommended at
the same interval as the ThC filters
cleaning.
A QRH procedure (called at the
end of the ECAM procedure) will
provide the flight crew with a second
reset procedure. The reason for
this second attempt is that a reset
is more likely to be successful at
lower altitude.
4.1 New Ecam Air Eng 1+2
Bleed Fault Procedure
A new ECAM AIR ENG 1+2 BLEED
FAULT caution and procedure was
designed (fig. 6).
Implementation is planned as follows:
q A320 Family: on the Flight Warning
Computer (FWC) F8 standard, certification Q4 2015
Figure 5
Evolution of A330
Dual Bleed Loss events.
q Fan Air Valve (FAV)
The following technical solutions
(ref. E) have significantly reduced
the number of bleed losses due to
overtemperature (fig. 5):
q A second reset at lower altitude
q A330: on the FWC T5 standard,
certification planned Q4 2012.
4. A320 Family/A330
New Operational
Procedure
A Dual Bleed Loss requires a quick
identification of the situation and a
rapid reaction.
Airbus has performed an operational
review of in-service events, which
led to the standardization of the
existing Dual Bleed Loss procedures. In order to simplify the crew’s
task, the DBL procedures now give
similar instructions whatever the
cause of the Dual Bleed Loss.
In essence the new procedure calls
for:
q A single reset of each engine
bleed (provided there is no bleed
leak*)
A reset may clear a fault on a bleed
system if that fault was as a result of
a temporary parameter fluctuation.
Typically, this can be due to a failure
of the system to properly regulate the
bleed pressure or temperature due
to engine thrust variation. In such
a case, a bleed reset may allow
recovery of normal operation provided the parameter is back within
its normal regulation range. Per-
4.2 New Qrh Air Eng 1+2
Bleed Fault Procedure
forming more than one reset would
unnecessarily delay the initiation of
the descent.
q If the reset is unsuccessful,
rapid initiation of the descent,
when above FL100
In case of Dual Bleed Loss at or
close to cruise altitude, the typical
fuselage leak rate leads to a cabin
altitude increase of up to around
1000 ft/min. Any delay in the descent
initiation will increase exposure to
an ECAM CAB PR EXCESS CAB
ALT warning, which requires a
mandatory emergency descent.
q APU start
In case of dual engine bleed failure,
the backup bleed source is the APU.
bleed selection when
within the APU bleed envelope
q APU
At lower altitude (FL220/200
depending on APU standard) the
APU bleed enables supply of the air
conditioning system, thus ensuring
cabin pressurization and preventing
a descent to FL100.
* In case of bleed leak, a specific procedure will apply.
Pending the implementation of
the new ECAM procedure, the
QRH current AIR DUAL BLEED
FAULT procedure will be enhanced
to be in line with the new ECAM
and renamed as AIR ENG 1+2
BLEED FAULT (Q1 2012).
Figure 6
Typical new ECAM
AIR ENG 1+2 BLEED
FAULT caution and
procedure
Issue 13 | January 2012
AIR ENG 1+2 BLEED FAULT
-X BLEED....................AUTO
-ENG 1 BLEED.........OFF THEN ON
-ENG 2 BLEED.........OFF THEN ON
.IF UNSUCCESSFUL:
-ENG 1 BLEED.................OFF
-ENG 2 BLEED.................OFF
-APU BLEED...................OFF
DESCENT TO FL100/MEA
-APU.......................START
-WING ANTI ICE...............OFF
-AVOID ICING CONDITIONS
.WHEN BELOW FL220 AND APU AVAIL:
-APU BLEED....................ON
MAX FL.......................220
BLEED 1+2 PROC.............APPLY
5. CONCLUSION
The consequences of Dual Bleed
Loss occurrences range from in-flight
turn backs to cabin depressurization
events followed by flight diversions.
Technical solutions have been
devised, which are summarized
in this article. They include new
maintenance and operational
procedures as well as redesigned
components available via retrofit.
These solutions have proved efficient as the number of events has
started to decrease, both for the
A320 Family as for the A330, in
the face of ever increasing fleets.
The handling of DBL events, should
they occur, will now be made easier.
A single and simple ECAM procedure
will cover all cases of Dual Bleed Loss.
This will assist crews in the identification and management of these
events in the most appropriate
manner (recovering bleed system
when possible, avoiding excessive
cabin altitude, continuing the flight
to destination or to a most suitable
diversion airport). An updated QRH
procedure will be published pending
the retrofit of the new FWC standards.
References
q Ref. A: A320 DBL Package (TFU 36.11.00.059 and SIL 36-057)
q Ref. B: A320/A330 Preventive Cleaning / Replacement of the Temperature
Control Thermostat Filter (SIL 36-055)
q Ref. C: A330 Solutions for Overpressure (TFU 36.11.00.069)
q Ref. D: New Pressure Transducer (SB A330-36-3039 and RIL 36-3039)
q Ref. E: A330 Solutions for Overtemperature (TFU 36.11.00.065)
9
10
Safety
Issue 13 | January 2012
The Airbus Safety Magazine
Issue 13 | January 2012
Thomas LEPAGNOT
Senior Engineer, A320/A330/A340 Standards
Flight Operations Support and Safety Enhancement
SPOILER DRIFT
The Fuel Penalty Factor
Failures Affecting the Fuel Consumption
A320 Family and A330/A340
1. Introduction
Monitoring the fuel consumption
all along a mission is one of the
most important tasks of the flight
crew. This general statement was
already highlighted in the Safety
First article “Low Fuel Situation
Awareness” published in issue n°6
(July 2008). This article stressed
the following points:
that have an impact on the fuel
consumption. The only exception
is the one engine out failure, once
confirmed in the FMS. For all other
cases, the FMS predictions should
be corrected to take into account
the consequences of these failures
in terms of excessive fuel consumption.
q The importance of the different
The purpose of this article is to present
new developments in terms of:
fuel checks in cruise, to detect an
abnormal fuel situation
q The functionality limitations of the
Flight Management System (FMS)
in terms of fuel predictions, under
non-nominal aircraft conditions.
In this new article, we will focus
on the second theme: The FMS
Estimated Fuel On Board (EFOB)
predictions do not currently take
into account the in-flight failures
q Documentation and procedure
that have been introduced in November of 2011
q Coming standards of Flight
Warning Computers that will soon
become available.
These enhancements were designed
to improve the crews’ awareness of
the fuel consumption increase generated by certain failures.
2. Failures
Affecting the Fuel
Consumption
All failures that affect the nominal
aerodynamic characteristics of the
aircraft will, also, increase its fuel
consumption. The additional drag
penalty drag has to be compensated
by an increase in thrust (to maintain
the same flight conditions) or by a
descent to a lower flight level (if
there is no thrust margin).
The two main sources of additional
drag are:
q A failure affecting the flight
control surfaces, which may lead
to three specif ic conf igurations,
generating each a different amount
of drag:
• The surface is blocked in its
full deflection position (runaway),
or
• The surface is free and floats
in the wind (zero hinge moment
position), or
• The surface (only applicable to
spoilers) slowly extends over time,
after the loss of its hydraulic actuation (spoiler drift, see explanations
in box below).
q A failure affecting the landing
gears or landing gear doors retraction function, which will lead
to the gears, or doors, remaining
extended.
In case of hydraulic system failure, some
spoilers will no longer operate. An antiextension device will avoid the deflection
of the spoiler. However, depending on the
condition of the spoiler servo control, this
anti-extension device could be sensitive
to temperature variations or prone to
actuator leak. In that case, the spoiler
may not be maintained retracted and
may extend over time up to its zero hinge
moment position.
Let us consider the cockpit effects of
such a failure mode on an A320:
q First, the Hydraulic failure (HYD G SYS
LO PR for instance), with all affected spoilers
indicated fault retracted in amber on the
ECAM Flight Control page (fig. 1A).
Figure 1A
A320 ECAM F/CTL page: affected spoilers indicated fault retracted
q If one of the affected spoilers (n°5 left,
for instance) drifts, no indication will appear
on the ECAM as long as the extension
value remains below 2.5°.
q Once it crosses that threshold, a F/CTL
SPLR FAULT amber caution is triggered
and the affected spoiler is indicated fault
deflected in amber on the ECAM F/CTL
page (fig. 1B).
q From then on, it is considered that the
affected spoiler generates a non negligible increase of the fuel consumption,
which will evolve over time, as the spoiler
extends further.
Figure 1B
A320 ECAM F/CTL page: spoiler n°5 indicated fault deflected
We can segregate these failures
into four systems : ELEC, F/CTL,
HYD, L/G.
note
Indeed, as the flight control surfaces
are all electrically controlled, and
hydraulically activated, some ELEC
and/or HYD failures will lead to the
loss of flight control surfaces (ailerons
and/or spoilers).
Figure 1C
Illustration of
spoiler drift
on an A330
11
12
Safety
Issue 13 | January 2012
MULTIPLE FAILURES
Some faults that independently do not generate any fuel consumption increase can, if combined, lead to
an overconsumption. This can be due to in-flight failures, or more likely, to the combination of a dispatch
under MEL followed by an in-flight failure. This kind of combination has to be taken into account in the
failure cases generating a fuel consumption increase.
To illustrate the concept of multiple
failures, let us consider an example
on the A330. The general architecture
of the aircraft’s flight control system
is is illustrated in fig. 2A.
Figure 2A
A330 Flight Control Architecture
The aircraft may be dispatched with
PRIM3 inoperative under MEL. This
implies that two pairs of spoilers
(spoilers n°1 and n°2) and the redundancy on both outboard ailerons are
lost (fig. 2B).
Figure 2B
Loss of PRIM3
If SEC1 fails in flight, the aircraft loses
an additional pair of spoilers (n°6)
as well as the left outboard aileron,
which goes to its zero hinge moment
position(fig. 2C).
Figure 2C
Loss of PRIM3 and SEC1
The simple failure of SEC1 taken independently, would have no effect on the fuel consumption. However,
combined with the loss of PRIM3 , it leads to drag being generated by the left aileron in the zero hinge
moment position.
The Airbus Safety Magazine
Issue 13 | January 2012
The flight control and landing gear/
landing gear doors malfunctions
may be caused by either simple or
multiple failures (see explanations
in box above).
3. Information
Provided to the
Flight Crew
up to Nov 2011
3.1 Failures Managed by Ecam
For failures affecting the fuel
consumption, a dedicated “INCREASED FUEL CONSUMP”
message is provided through the
associated ECAM STATUS page.
However, in the current FWC
standards, this line is not displayed
for all failures generating a fuel
consumption increase (in particular
for multiple in-flight failures or for
cases of dispatch under MEL) (fig. 3).
To obtain information on the consumption increase, the flight crew
had to refer, if time permitted, to the
description of the associated ECAM
alert in the FCOM. Retrieving this
information was therefore left to the
pilot’s initiative (fig. 4).
3.2 Failures Managed by Qrh
For failures that were managed
through the QRH, the additional
fuel consumption information was
directly provided in the QRH procedure (like for instance by a caution
for the LANDING WITH SLATS
OR FLAPS JAMMED procedure)
(fig. 5).
4. Information
Provided to the
Flight Crew
from Nov 2011
With the QRH revision of November
2011, the procedure has been improved to give better guidance and
more comprehensive information.
This procedure will be further supported by future Flight Warning
Computer (FWC) standards.
Figure 3
STATUS page of
L/G GEAR UPLOCK FAULT
PROCEDURES
ABNORMAL AND EMERGENCY PROCEDURES
27.01A
ABNORMAL AND
LANDING GEAR
EMERGENCY PROCEDURES
A330
FLIGHT CREW
OPERATING MANUAL
A318/A319/A320/A321
QUICK REFERENCE HAND BOOK
29 JUL 11
L/G GEAR UPLOCK FAULT (Cont'd)
LANDING WITH SLATS OR FLAPS JAMMED (Cont'd)
Ident.: PRO-ABN-32-D-00010765.0001001 / 17 AUG 10
Applicable to: ALL
Normal operating speeds
L12
 If FLAPS jammed > 0
STATUS
MAINTAIN SLAT/FLAP CONFIGURATION
MAX SPEED................................................................
250/.55
INOP SYS
L/G LEVER........................................................
KEEPMAX
DOWN
Recommended speed for diversion:
SPEED -10 kt
L/G RETRACT
(1)
Slats
Note: FUEL
‐ In
some cases, MAX SPEED -10 kt may be a few knots higher than the VFE.
INCREASED
CONSUMP
(1)
In
this situation, pilot may follow the VFE.
See
‐ In case of a go-around with CONF FULL selected, the L/G NOT DOWN
Flight with the landing
gear extended
hasatalanding
significant
on fuel consumption and climb
warning
is triggered
geareffect
retraction.
gradient (Refer to PRO-SPO-25-40 Climb).
Multiply fuel consumption by approximately 2.8.
MAX SPEED
Flaps
F=0
Figure 4
L/G GEAR NO
UPLOCK
S=0
LIMITATION
FAULT FCOM description
0<S<1
S=1
1<S≤3
S>3
CAUTION
0<F≤1
230 kt
215 kt
200 kt
177 kt
1<F≤2
2<F≤3
F>3
200 kt
185 kt
177 kt
(Not allowed)
200 kt
177 kt
185 kt
177 kt
177 kt
177 kt
For flight with SLATS or FLAPS extended, fuel consumption is increased. Refer
to the fuel flow indication. As a guideline, determine the fuel consumption in clean
configuration at the same altitude without airspeed limitation (e.g. From ALTERNATE
FLIGHT PLANNING tables) and multiply this result by 1.6 (SLATS EXTENDED) or
1.8 (FLAPS EXTENDED) or 2 (SLATS and FLAPS EXTENDED) to obtain the fuel
consumption required to reach the destination in the current configuration.
Figure 5
LANDING WITH SLATS OR FLAPS
JAMMED QRH procedure
4.1 QRH Development
All the information on the fuel consumption increase linked to system
failures is now gathered in the
ENVIn-Flight
A330 FLEET Performance chapter of
the QRH (FPE-FPF):
FCOM
←C
The Fuel Penalty Factors, assessing
the fuel consumption increase, are
provided through two different
tables:
q One table with an entry by
ECAM Alerts, and
q One table with an entry by INOP
SYS.
PRO-ABN-32 P 3/40
26 JUL 11
note
Only the failures leading to a fuel consumption increase greater than 3%
have been taken into account in these
tables.
13
14
Safety
Issue 13 | January 2012
4.1.1 ECAM Alert Table
For each ECAM alert impacting
the fuel consumption, The first table
(fig. 6A) provides:
A318/A319/A320/A321
QUICK REFERENCE HANDBOOK
q The conditions taken into account
to compute the Fuel Penalty Factor,
and
q The value of the corresponding
Fuel Penalty Factor.
4.1.2 INOP SYS Table
For each INOP SYS impacting the
fuel consumption, the second table
(fig. 6B) provides:
q The conditions taken into account
to compute the Fuel Penalty Factor,
and
q The value of the Fuel Penalty Factor
associated with the INOP SYS.
Figure 6A
A320 Fuel Penalty
Factor table / ECAM
alert entry
(1) During the flight, the spoiler(s) may gradually extend
and increase the fuel consumption.
(2) A spoiler can be suspected fully extended (runaway)
if high roll rate has been experienced immediately
after the failure, associated with a possible AP
disconnection. A visual inspection, if time permits,
can also confirm the full extension of the spoiler.
(3) T he maximum value of the Fuel Penalty Factor
provided in the table considers that the two pairs
of corresponding spoilers gradually extend during
the flight.
(4) The minimum value of the Fuel Penalty Factor
provided in the table considers that all spoilers
remain retracted. The maximum value has been
calculated considering that all impacted spoilers
gradually extend during the flight.
FPE-FPF
4.1.3 Utilization of the New QRH
Tables
24 NOV 11
The Fuel Penalty Factors provided
in the QRH tables are given as a
guideline. The flight crew should
confirm this Fuel Penalty Factor
by monitoring the actual fuel consumption.
2/4
FUEL PENALTY FACTORS/ECAM ALERT TABLE
q The critical inoperative system(s)
in terms of fuel consumption
IN FLIGHT PERFORMANCE
The Airbus Safety Magazine
SYS
ECAM ALERT
FUEL
PENALTY
FACTOR
CONDITIONS
If L(R) spoiler 3 is indicated extended
10 %
(at the time of the failure)
If L(R) spoiler 3 is indicated extended
SPLR 3
10 %
(at the time of the failure)
If one aileron is indicated fully extended
L(R) AIL
27 %
(upwards or downwards)
L(R) AIL FAULT
If one or both aileron(s) is/are indicated
L(R) AIL or L+R AIL
8%
partially extended
If one spoiler is suspected fully extended (2)
Cruise Conditions:
OPT SPEED................ GDOT +10KT
Whenever possible, target green dot speed
+10 kt to minimize fuel consumption.
However, if buffet is encountered at GDOT
55 %
speed +10 kt increase speed to fly out of
SPLR (affected)
buffet condition.
CRUISE ALT.................AS REQUIRED
Current Flight Level (FL) may not be
F/CTL
SPLR FAULT
maintained due to increased drag. Maintain
a cruise FL as high as possible.
If one spoiler or one pair of spoilers is
10 %
partially extended (zero hinge moment)
If spoiler 3 is partially extended after the loss
SPLR 3 with BLUE HYD
Up to 4 %
of the B hydraulic system (1)
If spoiler 1 or 5 is partially extended after the Up to 9 %
SPLR 1 or 5 with
(3)
GREEN HYD
loss of the G hydraulic system (1)
If spoiler 2 or 4 is partially extended after the Up to 9 %
SPLR 2 or 4 with
(3)
YELLOW HYD
loss of the Y hydraulic system (1)
FLAPS FAULT/LOCKED
FLAPS
If Flaps are extended
80 %
SLATS FAULT/LOCKED
SLATS
If Slats are extended
60 %
SLATS + FLAPS FAULT/LOCKED
SLATS+FLAPS
If Slats and Flaps are extended
100 %
If L(R) spoiler 3 is indicated extended
B SYS LO PR
SPLR 3
10 %
(at the time of the failure)
If L(R) spoiler 5 is indicated extended
G SYS LO PR
SPLR 1+5
10 %
(at the time of the failure)
If L(R) spoilers 2 and 4 are indicated
Y SYS LO PR
SPLR 2+4
20 %
extended
(at the time of the failure)
Both ailerons are failed
10 %
to
L+R AIL SPLR
Spoilers 1, 3 and 5 (1)
G+B SYS LO PR
HYD
15 %
1+3+5 L ELEV
Left elevator is failed
(4)
RAT is extended
0%
Stabilizer is jammed
to
SPLR 1+2+4+5
G+Y SYS LO PR
10 %
STABILIZER
Spoilers 1, 2, 4 and 5 (1)
ELEC
AC BUS 1 FAULT
(equivalent to B SYS LO PR)
DC ESS BUS FAULT
(equivalent to B SYS LO PR)
FUEL CRITICAL
INOP SYS
SPLR 3
(4)
B+Y SYS LO PR
SPLR 2+3+4 R ELEV
3%
to
10 %
Spoilers 2, 3 and 4 (1)
Right elevator is failed
RAT extended
(4)
SHOCK ABSORBER FAULT
GEAR NOT UPLOCKED
All landing gears are extended
L/G RETRACT
180 %
(Also refer to PRO-SPO-25-10)
L/G BOGIE ALIGN FAULT (option)
FPE-FPF
GEAR UPLOCK FAULT
DOORS NOT CLOSED
L/G DOOR PERFORMANCE
All landing gears doors are extended
15 %
IN FLIGHT
(1)
A318/A319/A320/A321
During the flight, the spoiler(s) may gradually extend and increase(s) the fuel consumption.
24
NOV 11
QUICK
REFERENCE
HANDBOOK
FPE-FPF
(2) A spoiler can be suspected fully extended (runaway) if high roll rate has been experienced immediately after the failure,
(4) associated
The minimum
of the Fuel
Penalty Factor
in the PERFORMANCE
table
considers
thatcan
all also
spoilers
remain
Theofmaximum
withvalue
a possible
AP disconnection.
Aprovided
visual
inspection,
if time
permits,
confirm
the retracted.
full extension
the
IN
FLIGHT
value has been calculated considering that all impacted spoilers gradually extend during the flight.
spoiler.
A318/A319/A320/A321
24 NOV
11
(3)QUICK
The REFERENCE
maximum value
of the Fuel Penalty Factor provided in the table considers that the two pairs of corresponding
spoilers
HANDBOOK
gradually extend during the flight.
(4) The minimum value of the Fuel Penalty Factor provided in the table considers that all spoilers remain retracted. The maximum
value has been calculated considering that all impacted spoilers gradually extend during the flight.
3/4
3/4
FUEL PENALTY FACTORS/INOP SYS TABLE
AIB
SYS
L(R) AIL or L+R AIL
Figure 6B
A320 Fuel Penalty
Factor table / INOP
SYS entry
SYS
F/CTL
L/G
F/CTL
L/G
FUEL PENALTY
FACTOR
FUEL PENALTYIf oneFACTORS/INOP
SYS TABLE
or both aileron(s) is/are indicated partially
INOP SYS
INOP
SYS
FLAPS
SLATS
L(R)
AIL or L+R AIL
SLATS+FLAPS
L/G
DOOR
FLAPS
SLATS
SLATS+FLAPS
L/G DOOR
CONDITIONS
extended
If Flaps are extended CONDITIONS
IfIf Slats
extended
one orare
both
aileron(s) is/are indicated partially
Ifextended
Slats and Flaps are extended
All
landing
doors are extended
If Flaps
aregears
extended
If Slats are extended
If Slats and Flaps are extended
All landing gears doors are extended
8%
FUEL PENALTY
80
%
FACTOR
60 %
8 %%
100
15
80 %
60 %
100 %
15 %
Issue 13 | January 2012
ECAM MANAGEMENT
PF
PNF
DETECTION
ECAM ACTIONS
ECAM PROCEDURE
SYSTEM DISPLAY
When should these two QRH tables
be used?
According to the ECAM management philosophy, after the ECAM
actions are completed, the flight
crew should perform a situation
assessment (fig. 7).
STATUS
Figure 7
Extract of the
Procedure Data
Package (PDP) /
ECAM Management
SITUATION ASSESSMENT
DECISION
SYNTHESIS
The situation assessment by the
flight crew has been amended to
include an evaluation of the fuel
consumption whenever the ECAM
STATUS page displays:
REV09
q INCREASED FUEL CONSUMP
q A flight control surface in the
INOPS SYS
q L/G RETRACT or L/G DOOR
in the INOP SYS
To do so, the flight crew should
now refer to the Fuel Penalty Factor
in the QRH (fig. 8).
Figure 8
Extract of the
Procedure Data
Package (PDP) /
ECAM Management /
Situation Assessment
In such cases, two different situations
may be encountered:
How should these two QRH tables
be used?
The Fuel Penalty Factors in the
QRH tables have been calculated
taking into account the aircraft
configuration, speed or altitude
(when mentioned) described in
the CONDITIONS column. Ensure
that these conditions are well met
(or applied) before taking into
account the corresponding Fuel
Penalty Factor.
To determine whether a Fuel Penalty
factor is applicable, the crew needs
to proceed in two steps:
q First enter the ECAM alert table,
then
q Enter the INOP SYS table.
The second table, INOP SYS, is
provided to cover the cases of multiple in-flight failures or dispatch
under MEL.
q The ECAM alert associated with
the failure generating the increase
of fuel consumption is not mentioned
in the ECAM alert table. This is
typically the case for failures, which
do not impact the fuel consumption when taken independently, but
which do lead to an increase in fuel
burn when combined with previous
failures.
In this circumstance, the flight
crew will find the applicable Fuel
Penalty Factor in the INOP SYS
table.
q The ECAM alert associated with
the failure generating the increase
of fuel consumption is mentioned
in the ECAM alert table. However,
due to previous failures, an additional INOP SYS on the STATUS
page (different from the one(s)
mentioned in the FUEL CRITICAL
INOP SYS column for the cor-
responding ECAM alert) has an
impact on the fuel consumption.
In that circumstance, the flight crew
will find another applicable Fuel
Penalty Factor in the INOP SYS
table.
Once the pertinent Fuel Penalty
Factors have been identified, the
procedure is as follows:
q If only one Fuel Penalty Factor
(FPF) is applicable:
ADDITIONAL FUEL =
(FOB - EFOB at DEST) x FPF
q If two or more Fuel Penalty Factors
(FPF) are applicable:
ADDITIONAL FUEL =
(FOB - EFOB at DEST)
x (FPF1 + FPF2 +...)
This ADDITIONAL FUEL must
be added to the fuel predictions
provided by the FMS.
15
16
Safety
Issue 13 | January 2012
The Airbus Safety Magazine
Issue 13 | January 2012
Paule BOTARGUES
Engineer, Automatic Flight Systems Research,
Engineering Department
Example of Utilization of QRH tables
The Airbus TCAS
Alert Prevention (TCAP)
To illustrate the method, let us consider
an A320 under the following conditions:
q A dispatch with the ELAC 1 inoperative under MEL, and
q An HYD G SYS LO PR ECAM caution
in flight
These two failures lead to the loss of
the left aileron:
Therefore, the INOP SYS will display
“L AIL” that should lead the flight crew
to enter the QRH Tables.
In the ECAM alert table:
FPF (HYD G SYS LO PR) = 10 %
(if spoiler(s) are indicated extended)
In the INOP SYS table:
FPF (INOP SYS: L AIL) = 8 %
4.2 ECAM Development
With future Flight Warning Computer (FWC) standards, all failure
cases leading to an increase in fuel
consumption of more than 3%,
including multiple in-flight failures
and dispatch under MEL, will trigger
a “FUEL CONSUMPT INCRSD”
message on the ECAM STATUS
page. This message will be complemented with a “FMS PRED
UNRELIABLE” line to highlight
the unreliability of the FMS (fig. 9).
The same wording will also be used
in the associated ECAM procedure.
All these improvements will be
introduced in the following FWC
standards:
q A320 Family: H2F7 standard
(certification planned for December
2012)
q A330 and A340-500/600: T5
standard (certification planned for
January 2013)
q A340-200/300: L13 standard
(certification planned for August
2013).
Two possible cases may be encountered:
q If the Fuel Penalty Factor of the HYD G SYS LO PR ECAM alert is not applicable (spoiler remains retracted), apply the Fuel Penalty Factor related to the INOP SYS “L(R) AIL” partially extended.
ADDITIONAL FUEL = (FOB - EFOB at DEST) x 8 %
q If the Fuel Penalty Factor of the HYD G SYS LO PR ECAM alert is applicable (spoiler extended), add the
corresponding factor to the Fuel Penalty Factor related to the INOP SYS “L(R) AIL” partially extended.
ADDITIONAL FUEL = (FOB - EFOB at DEST) x (10 % + 8 %)
1. Introduction
2. Level-Off RAs
The Traff ic Alert and Collision
Avoidance System, known as
TCAS, has been introduced in the
90’s to prevent the risk of mid-air
collisions. Today this safety goal
has globally been reached.
Level-off RAs occur during 1000ft
level-off manoeuvres while everything is correctly done by the crew
with regards to operations and
clearance.
However, a recurrent side-effect of
TCAS introduction can be observed.
This side-effect is what we call the
‘nuisance’ Resolution Advisories (RAs)
or the operationally ‘undesired’ RAs,
which occur during 1000ft separation
level-off manoeuvres.
A new Safety Initiative has been
launched by Airbus to solve
this issue: The TCAS Alert Prevention (TCAP), a new altitude
capture enhancement to minimize
cases of TCAS level-off RAs.
Figure 9
Future A330 STATUS page of
the F/CTL L(R) INR (OUTR) AIL FAULT
The objective of this new TCAP
feature is twofold:
5. CONLUSION
After an in-flight failure, it is essential for the flight crew to have
a clear view of all the operational
consequences generated by this
failure. In particular, when the fuel
consumption is affected, the pilot
should have means to estimate this
impact.
This is the purpose of this new policy
supported by new QRH tables and
future developments implemented
in the next FWC standards. The
information is now concentrated in
one part of the Operational Documentation (simplified access), takes
into account more operational cases
(multiple failure, dispatch under
MEL), and the associated procedure
is more formalized.
This policy ensures a standardized
and common treatment of all the
failures impacting the fuel consumption, by giving the same level
of information to all flight crew.
It improves the crew awareness on
consequences of such failures, and
as a result, represents a new step
in the safety of airline operations.
These operationally ‘undesired’
RAs can be characterised by the
two following typical encounter
geometries:
q One aircraft (in blue on fig. 1) is
intending to level-off at a given level
while another aircraft (in green on
fig. 1) is already levelled at the adjacent level (1000ft above or below
the first aircraft’s intended level):
Climb ! Climb !
q To reduce the number of undesired TCAS RAs occurring during
1000ft level-off encounters. This is
done by adapting the altitude capture law, so as to soften the aircraft
arrival to an intended altitude when
traffic is confirmed in the vicinity.
q Not to degrade the aircraft performance, in particular in descent,
by a premature and excessive reduction of the vertical speed to
reach the altitude target, when it is
not justified.
Traffic ! Traffic !
FL110
FL100
Adjust V/S ! Adjust !
Traffic ! Traffic !
Figure 1
‘Undesired’ TCAS RAs
occurring during a single
1000ft level-off manoeuvre
17
18
Safety
Issue 13 | January 2012
The Airbus Safety Magazine
q ICAO (PANS-OPS Doc. 8168)
q One aircraft is climbing to level-
off at a given level while another
aircraft is descending to level-off at
the adjacent level, 1000ft above the
first aircraft’s intended level (fig. 2).
recommend to adopt a vertical
speed below 1500ft/min throughout
the last 1000ft of climb or descent to
the assigned altitude.
Traffic ! Traffic !
Adjust V/S ! Adjust !
q Table 1 also includes also includes
the limits in vertical speed from
three other sources.
Although these RAs do not imply
a ‘real’ collision risk, they remain
very stressful alerts. Above all, they
impose - by procedure - an avoidance
manoeuvre to both aircraft, leading
to unnecessary deviations from
initial trajectories and to potential
repercussive traffic perturbations.
FL110
FL100
Let us take the example of an A320
(medium weight/CG, selected speed
300kt) climbing to FL130 with a
rate of climb of 2800ft/min, while
an A340-600 (light weight/medium
CG, selected speed VMO-20kt) is
descending to FL140 with a rate of
descent of 2200 ft/min.
Adjust V/S ! Adjust !
Figure 2
‘Undesired’ TCAS RAs
occurring during a double
level-off manoeuvre
Traffic ! Traffic !
In such an encounter, the A320
TCAS will trigger a Traffic Advisory
(TA) at FL116 and a RA at FL123.
Simultaneously, the A340-600 TCAS
will set off a TA at FL153 and a RA
at FL147 (fig. 3).
3. Recommendations to Prevent
these RAs
As shown on table 1, the preventive
rates to apply vary slightly depending
on who is expressing the rule:
EUROCONTROL ACAS and RVSM programs
Swiss Regulation
RA
Figure 5
FMA upon TCAP
activation when
initially in OP CLB
FL147
FL140
The objective of this new TCAP
feature is twofold:
FL123
FL120
RA
FL116
TA
FL100
08.00.00
q To reduce the number of unde-
08.00.30
08.01.00
08.01.30
08.02.00
08.02.30
08.03.00
08.03.30
08.04.00
08.04.30
08.05.00
sired TCAS RAs occurring during
1000ft level-off encounters. This is
done by adapting the altitude capture law, so as to soften the aircraft
arrival to an intended altitude when
traffic is confirmed in the vicinity.
Dist. to level
2000 ft
1000-2000 ft
1000 ft
2000 ft
1000 ft
1000 ft
1500 ft
TA
TCAP Control/Law
q Not to degrade the aircraft performance, in particular in descent, by
a premature and excessive reduction
of the vertical speed to reach the altitude target, when it is not justified.
In response to these requests for
improvement, Airbus launched the
feasibility study of a new system
called TCAS Alert Prevention or
TCAP.
FL153
Vz
1500 ft/min
500-1500 ft/min
1500 ft/min
2000 ft/min
1000 ft/min
1000 ft/min
1500 ft/min
Table 1
Recommendations to prevent level-off RAs
4. The Tcap Function
TA
FL160
q The FAA (AC20-151A, Appendix
A Section III) call for a reduction
of the vertical speed to between
500 and 1500ft/min, when between
1000 and 2000ft above or below
the assigned altitude.
The second set of recommendation
has been expressed by the French
accident investigation authority
Bureau d’Enquête et d’Analyses
(BEA) following a mid-air incident,
in March 2003, where a wrong
response to an “ADJUST V/S”
RA was observed in a context of
a 1000ft level-off encounter. The
BEA recommended that aircraft
manufacturers study the possibility
of taking into account TCAS alert
triggering thresholds into their altitude capture laws.
DLH
FL180
q Airbus (FCOM) recommend to
limit the vertical speed to 1500 ft/min
during the last 2000ft of a climb or
descent.
As a matter of fact, these recommendations are rarely applied. Several
airlines do not have them incorporated
in their operational recommendations.
Even when they are, some pilots
confess they are not always applied.
As a result there is still a significant
number of undesired RAs observed
during 1000ft level-off manoeuvres.
AI FCOM
FAA
ICAO
This recommendation was followed
by EUROCONTROL within the
ACAS Bulletins and by several airlines who requested a modification
of the altitude capture control laws
with an earlier reduction of the vertical rate to prevent such recurrent
undesired RAs.
Figure 3
Example of nuisance
TCAS alerts occurring during
a double level-off manoeuvre
The first recommendation calls for
pilots to reduce the vertical speed
when approaching the assigned
altitude or flight level.
This preventive action limits the
vertical convergence between
aircraft and thus prevents crossing
the TCAS alert triggering thresholds.
Issue 13 | January 2012
The TCAP activation logic is based
on the Traffic Advisory (TA) triggered by the TCAS, which clearly
confirms the presence of traffic in
the aircraft vicinity.
• If the aircraft is initially in a vertical
guidance mode other than the
altitude capture mode (for example
in a climb or descent mode),
the vertical mode automatically
reverts to the altitude capture
mode (ALT* for Airbus HMI)
with the new TCAP altitude control
law active (ALT*TCAP control law)
(fig. 5).
The activation of TCAP is fully
transparent to the pilot who will
note the same mode changes with
TCAP as without TCAP. The TCAP
case only resulting in an earlier reduction of the Rate Of Descent/
Rate Of Climb (ROD/ROC). This
means that upon TCAP activation
at TA:
• If the vertical mode is initially the
altitude capture mode (ALT* with
the conventional altitude capture
control law active), the vertical
mode remains the altitude capture
mode but with the new ALT*TCAP
control law active. The Flight
Mode Annunciator still displays
ALT* (fig. 6).
Conventionnal ALT*
Control/Law
Figure 6
FMA upon TCAP
activation when
initially in ALT*
TA
TCAP Control/Law
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20
Safety
Issue 13 | January 2012
Once activated, the ALT*TCAP control law remains active till the end
of the capture (with ALT* mode
engaged) even if the triggering TA
ceases. This is to avoid triggering
a new TA.
The Airbus Safety Magazine
Open
TCAP activation can be noticed through
Descent guidance mode change and 0.15 g nose up
mode
Figure 8
Early TA occurring
when the aircraft
is in descent
Finally, it is important to note that
TCAP activation does not impact
the lateral trajectory and associated
lateral guidance mode, nor the AutoPilot, Flight Director and AutoThrust engagement status.
TA
Issue 13 | January 2012
Before
After
TCAP equipped
Intermediate
rate of descent
FL180
FL180
FL target
+2000 ft
TA
1500 ft/min
TA
RA
FL160
FL160
FL153
FL153
FL147
FL140
FL140
FL123
FL120
FL120
FL target
OP DES
Without TCAP
5. Adapted Tcap
Altitude Capture
Control Law
(Alt*Tcap)
With TCAP
When in ALT*TCAP control law, a
vertical load factor of 0.15g is applied to ensure a rapid reduction of
the vertical speed and thus a more
efficient prevention of the RAs. It
also gives a reliable sensorial feedback to the crew to indicate TCAP
function activation if ALT* mode
was previously engaged.
The ALT*TCAP vertical speed targets
have been defined so as to efficiently
prevent level-off RAs while minimizing the increase of the altitude
capture phase duration. They are
function of current aircraft vertical
speed and distance to targeted level
at the time of the TA and are computed in decreasing sequence in case
of consecutive vertical speed targets
(e.g. if a new TA occurs).
The average impact on the altitude
capture time is an increase of 40
seconds compared to the conventional
altitude capture law, remembering
that TCAP control law activation is
limited to a TA occurrence.
Altitude capture phase duration is longer
due to TCAP activation
Examples
Exemple 1: Early TA occurring when the aircraft is in descent
The aircraft is descending in OP DES mode when a TA occurs above the
last 2000ft. The ALT* mode immediately engages with ALT*TCA control law active and an associated vertical load factor of 0.15g: the rate of
descent is reduced to an intermediate vertical speed target greater than
1500ft/min till reaching the last 2000ft, where the vertical speed target
becomes 1500ft/min (fig. 8).
Altitude
Capture
mode
TCAP activation can be noticed
through 0.15 g nose up
TA
FL target
+2000 ft
1300 ft/min
1600 ft
FL target
Without TCAP
With TCAP
TA
FL100
ALT*
OP DES
Figure 9
TA occurring
during an
altitude
capture
FL116
TA
FL100
TCAP
The objective of the Alt*TcaP control law is to acquire and hold one
or several consecutive vertical speed
targets until the aircraft reaches its
intended altitude by adopting a
classical 0.05g parabola profile.
RA
FL116
ALT*
ALT*
ALT*
TCAP
Altitude capture phase duration is longer
due to TCAP activation
Non equipped with TCAP
08.00.00
08.00.30
08.01.00
08.01.30
Figure 10
TCAP benefits on
a double level-off
encounter
08.02.00
08.02.30
08.03.00
Classical ALT*
08.03.30
08.04.00
08.04.30
2 RAs
08.05.00
08.00.00
08.00.30
08.01.00
08.01.30
08.02.00
New ALT*
08.02.30
08.03.00
08.03.30
08.04.00
08.04.30
08.05.00
No more RAs
Benefit for the non-equipped aircraft also !
Exemple 2: TA occurring during
an altitude capture (in ALT*)
The aircraft is performing an altitude capture on the conventional
0.05g parabola capture prof ile
(ALT* mode) when a TA occurs.
The ALT*TCAP law automatically
activates to quickly reduce the rate
of descent, shortcutting the parabola
with a vertical load factor of 0.15g
(ALT* mode remains engaged).
The rate of descent is reduced to a
vertical speed target between 1200ft/
min and 1500ft/min depending on
aircraft distance to flight level at the
time of the TA. till the end of the
capture (fig. 9).
6. Expected
Benefits
An operational and safety performance assessment was performed in
the frame of the Single European
Sky ATM Research (SESAR) project
to assess the impact of the new Airbus
TCAP solution, based on a large
encounter model representative of
operations in Europe.
The assessment showed that more
than 95% of the 1000ft level-off
RAs were avoided through the use
of TCAP. Since 1000ft level-off
RAs represent more than 55% of
all RAs, the project concluded that
TCAP may halve the overall number
of RAs for an equipped aircraft.
Another observed relevant result
was that only one aircraft of the encounter needs to be equipped with
TCAP to allow RAs prevention on
both aircraft (fig. 10).
7. Conclusion
With significant operational benefits
such as more than 95% level-off
RAs avoided, leading to an overall
number of RAs cut by two without
debasing safety, TCAP establishes
as a promising standard.
These benefits will be associated to
the following outcomes:
q For the crew: less stress due to a
reduced number of RA situations,
q For ATC: less unnecessary traffic
perturbations due to ‘undue’ avoidance manoeuvres.
The TCAP will also contribute to
the crew workload alleviation: even
though pilots still have to maintain
awareness and vigilance over near
by traffic, they will not have to reduce ROC/ROD as a precautionary
measure. The pilots will just have to
monitor the Auto Pilot or the Flight
Director and to verify its reaction in
accordance with their expectations.
This new TCAP altitude capture
enhancement will be available on
all Airbus Fly-By-Wire aircraft, including the A380 and A350, in the
near future. The certification targets
are anticipated between end 2011
and mid 2013, depending on the aircraft type.
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Safety
Issue 13 | January 2012
The Airbus Safety Magazine
Issue 13 | January 2012
Claude LELAIE
Experimental Test Pilot
A380: Development
of the Flight Controls
Part 1
on a quad than on a twin due to the
number of rotors involved. It is to
be noted that this scenario, while
extremely rare, happened recently,
on an A380 from Qantas taking off
from Singapore. Even though the
aircraft was in a severely damaged
and degraded situation, the crew
had all the means to land safely,
and the analysis of the event confirmed that the design, in terms of
reconfiguration choices, was appropriate.
This article is the first of a series
intended to explain what has been
done for the development of the
flight controls laws of the A380.
The General Principles of the Design
Very early in the development
process, the design office has to
take many important decisions related to flight controls such as how
many computers, flight controls
surfaces, and hydraulic circuits are
needed. All that is dictated by the
analysis of failures, associated with
a first estimation of the likely flight
characteristics. In case of multiple
failures, the aircraft must remain
flyable.
One of the failures that could have
the most adverse consequences and
that leads to a lot of decisions is the
non-contained explosion of an engine rotor disc. It is assumed that a
part of this disc will penetrate the
fuselage or the wing with “high”
energy. The engine is designed and
built in such a way that this should
not happen, but this is a supplementary precaution. The potential
trajectories of this part are computed
according to very precise rules. It
must be checked that all the energy sources (mainly electricity and
hydraulic) will not be affected at
the same time, which could have
catastrophic consequences. Obviously, this study is far more complex
Numerous other factors are taken
into account when choosing the
general architecture. The most
important is the need to minimise
weight, obviously whilst keeping
the same level of safety.
Figure 1
A380 Iron Bird
The development of the flight controls laws for a Fly-By-Wire aircraft
is a complex process. It starts by
computations based on estimated
aerodynamic models of the aircraft,
which are then checked and adjusted
thanks to wind tunnel tests. This
allows a first version of the computers to be prepared. The next step
is the installation of these computers on a simulator where the latest
aerodynamic models have been
integrated. Evaluations can start,
first with “development simulator”
pilots specialized in this job, and
then with the test pilots nominated
to follow the program. At the beginning, numerous small problems
are found and there is a progressive
evolution of the computers. The
real proof comes with the test flight
itself as, even if the models are generally reliable, they are rarely fully
representative of the aircraft at low
speed, high speed and in the ground
effect. Also, at the beginning of
the flight tests, for the first time,
pilots are exposed to the accelerations of the aircraft in response to
their commands. Flexibility of the
structure can have consequences
on comfort, but can also induce effects on the flying characteristics.
Often, the models used for computations or in the simulator are correct so that after tuning on ground
and validation in flight, there is
nothing else to do. But it occasionally happens that the aircraft
behaviour is not in line with the
expectations and an aerodynamic
identification in flight is needed to
allow further tuning of the models
in order to enable the design office
to define the next standard of the
computers. Sometimes it is difficult because the modelling of the
ground effect is not satisfactory or
the flexibility of the aircraft does
not permit a correct simulation. In
this case, the development has to be
performed in two phases, first with
models and then directly in flight.
When in flight, engineers and pilots
decide in real time what adjustments
are necessary. They are using their
knowledge, judgement, common
sense and feelings (seat of the
pants flying). Some non-specialists
consider that the flight test task is
only to validate results obtained in
a simulator. This is not correct, as,
for a significant number of tests,
methodologies have not evolved
since the last century, except for
the help given by the computers.
Most of the time, qualitative feelings
and impressions are still showing the
way.
In order to save time, the flight test
engineers have a tool called AFDX
Digital Injection System (ADIS),
which allows them to modify in
real time some characteristics of
the computers. For safety reasons,
all the new possible adjustments
are checked in a simulator before
using them in flight.
The development of the flight controls laws is a fascinating adventure:
every day there are new surprises,
some good and some bad. The A380
has not been the most difficult aircraft
in this respect, thanks to the excellent
aerodynamic characteristics.
Fly-By-Wire
and Associated
Improvements
Fly-By-Wire has brought a lot to
aviation. Obviously the ease of
flying and the protections to avoid
loss of control are well known, but
that is not all.
In the past, flight controls were
designed to meet two sets of criteria:
they had to be “well harmonised”
and had to meet the criteria for certification. With Fly-By-Wire, three
possibilities have been added: improve safety by restricting manoeuvres which could lead to a loss of
control, reduce the weight of the
structure with the prohibition of
some actions, which may increase
the loads and finally improve comfort for the passengers. Adding all
these functions leads to more and
more complexity for the flight controls computers.
The Main A380
Characteristics
A general description of the main
characteristics of the A380 flight
controls will allow us to gain a better
understanding of the tests performed.
The A380 has seven flight controls
computers: three Primary Computers (PRIMs), three Secondary
Computers (SECs), and one Back
Figure 2
A380 EBHA Rudder
Up Control Module (BCM). Any
of the three PRIMs can ensure the
full control of the plane without restriction. The SECs do not provide
stabilized control laws as do the
PRIMs but they are more robust to
the loss of some information. They
also have different software than
the PRIMs so that a bug in one category of computer does not “contaminate” the others. All computers
have a command and a monitoring
lane. Finally, there is a BCM, available in case of failure of all PRIMs
and SECs.
The A380 has only two hydraulic circuits instead of three on the Airbus of
the previous generations. The third
circuit has been replaced by local
hydraulic generation: for some servo-controls, a small electrical motor creates the hydraulic energy to
power it. These systems are called
EHA (Electro Hydraulic Actuator)
or EBHA (Electro Backed up Hydraulic Actuator: fig. 2). This new
type of architecture with only two
circuits allows the saving of several
hundred kilograms on the A380,
mainly thanks to the reduction of the
number of pipes. It also creates a new
level of system segregation safety.
Some control surfaces have been
split into several parts controlled
by different electrical and hydraulic sources. There are two rudders
instead of one on all other Airbus
and four elevators instead of two. On
each side, there are three ailerons
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Safety
Issue 13 | January 2012
instead of one on the A320 family and
two on the A340 and A330. Each of
the surfaces (except the spoilers) is
activated by two servos using different hydraulic circuits or EHA or
EBHA. Two or three different computers (PRIM and SEC plus BCM)
control each of the servos. Therefore,
a lot of failures are needed to lose
the control of one surface.
When the four engines (or their generators) and the APU are no longer
available, electricity is coming from
a Ram Air Turbine (RAT).
The Identification
of the Aircraft
To ensure that the adjustments to
the control laws are well adapted
to the characteristics of the plane,
the design off ice needs a good
aerodynamic model. This is initially achieved through simulation.
However some tuning can only be
finalized and validated in flight.
So, the identification of the aircraft
stability and control characteristics
in flight is among the first priorities
of the program. On the A380, about
one month after the beginning of
the flight tests, in April 2005, flight
16 was devoted to identification
of these characteristics in pitch.
Then, during the months of July and
August, about 15 flights were dedicated to similar tests in roll, pitch,
effect of the engines… More were
performed during the following
months.
These identification flights are
completely different from those
which must be done at the end of
the development in order to prepare
the aircraft models for installation
in the training simulators. For these
last flights a very specific process
has to be followed. The training
simulators do not need to represent
the flight characteristics in extreme
situations. On the other hand, in
order to develop the flight control
computers, the design office needs
to have a good identification of the
aerodynamic characteristics at the
limits of the flight envelope.
The Take-Off
Rotation Law
On the A340-600, the development
of the take-off control law proved
to be rather difficult. It is worth explaining the issue here to show the
kind of obstacles that can be found.
All the pilots agreed that, on the
A340-300, the reaction in pitch
during the rotation at take-off,
whilst being acceptable, was a bit
sluggish. As the A340-600 was
planned to be about 100 tons heavier
than the A340-300 and longer
by about 12 meters, a study was
launched to improve the reaction of
the -600 during the rotation. Numerous tests were performed in the
simulator and then the new control
law was installed on the A340-300
used for development. The team
was happy with the results. Subsequently, the take-offs of the first
two flights of the A340-600 were
performed in direct law in order to
improve progressively our knowledge of the aircraft. Following the
landing from the second flight, it
was planned to perform another
take-off with the brand new rotation law. It just happened that the
Captain of the A340-600 had been
in charge of the development of
this law. At the beginning of the
manoeuvre, the aircraft exhibited
a strong Pilot Induced Oscillation
(PIO). The pilot reacted naturally
to an unexpectedly strong response
of the aircraft. The oscillations
stopped after six cycles.
Why this surprise, as everything
was well prepared? The forward
part of the A340-600 is longer than
on the -300 and, with this lever,
the crew had the feeling of being
projected too quickly into the air
and therefore reacted immediately,
creating this PIO. All the work done
prior to the flight could not be used
as such. So, after a minimum of
development in the simulator,
to have a good starting point for
the control law, the tuning was
performed during a flight with
around 15 take-offs.
The principle is rather simple: with
the help of the ADIS, at each take-
off, it is possible to improve what
the pilots are feeling and the flight
engineers have on their traces. As
an example, the law can be made
more or less efficient at the initial
pilot command. It is also possible
to reduce the pitch rate when approaching the take-off attitude,
but not too early and not too late.
If there is a risk of tail strike, the
pitch rate must also be controllable
to almost zero very quickly. The
flight test engineers have to play
with a lot of variables such as precommand, damping, filtering and
so on, so as to reduce the take-off
distances and ensure safety in all
the critical cases such as engine
failure, early rotation… To perform
this tuning well they must have a
perfect understanding of the effect
of all parameters.
This example shows the limits of
what is possible to perform with
models or with the simulation for
some flight phases, particularly
close to the ground. However, the
conclusion must not be that models
have to be disregarded. Very good
preparation is fundamental in order
to have a solid starting point and
to give to the flight test engineers
well-adapted tools with the ADIS.
After the lessons of the A340-600,
we decided to keep the same methodology to develop the rotation law
of the A380: a basic and simple
preparation using models and simulators followed by the development
with flight tests.
For all these tests: development of a
rotation law and, later on, measurements of take-off distances, there is
always a risk of tail strike because
we are frequently on the limit of
manoeuvrability of the aircraft.
Therefore, the aircraft is equipped
with a tail bumper, the same that is
used for the VMU tests.
The first flight for development of
the A380 take-off rotation law was
performed on December 29th 2005
with a very experienced crew: two
test pilots, one test flight engineer
(in the cockpit) and two flight test
engineers both specialists of flight
controls. After 15 take-offs, the
The Airbus Safety Magazine
Issue 13 | January 2012
pilot encountered Pilot Induced
Oscillations (PIO) in this flight
phase. The reason is that the A340
touches down with a rather high
pitch attitude, and on the rear
wheels of the bogies having a “nose
up” position. Added to which, the
touchdown of the nose wheels is
performed with a slight nose down
attitude. The nose wheels, and obviously the pilots, must “descend”
from a relatively large height at
landing. This “de-rotation” law
reduces the authority of the stick
in pitch during this phase in order
to be able to smoothly control the
nose gear to the ground, without
risk of PIO.
results were satisfactory. Later on,
in February 2006, another flight
allowed the team to fine-tune the
protection, which was designed to
avoid getting a tail strike. It is to
be noted that during these tests, we
did experience a slight tail strike
on the tail bumper, proof that we
were looking for the minimum
margin while keeping the safety
level. The computations performed
later on, demonstrated that the tail
strike would not have happened on
the fuselage without the installation of the bumper. Finally, a last
flight was performed at the beginning of March 2006 to validate the
law at very heavy weights, as the
behaviour has to be checked for all
the weight and CG combinations.
The first take-off was performed
at 596,5 tons, more than 30 tons
above the MTOW. Our experience
has shown that it is always better to
be heavier for this type of flight as,
very often, our customers are asking for an increase of the MTOW
very quickly after entry into service. This way of working avoids
launching, later on, new tests which
could even lead to a further modification of the law. Additionally,
sufficient fuel was necessary to fly
to Istres Air Force Base (South of
France) to perform all the tests. The
choice of Istres airport to perform
this flight was due to the runway
length of 5000 meters, which al-
Figure 3
A380 take-off
from ToulouseBlagnac Airport
lowed us to be efficient after each
take-off by executing overweight
landings without overheating the
brakes. These landings added to the
difficulty of the tests.
Immediately at the end of the development of this law, the flights
for measurements of take-off distances started with EASA crews.
The Landing
Pitch Law
The development of the pitch law
at landing was quite quick. From
the beginning, we were aware that
landing the A380 was very easy.
However some adjustments were
necessary for the various flight
conditions: weights and CG positions. For the flight part, an initial
tuning was performed as the controls were judged to be a bit too
sensitive.
But the main modification was the
suppression of what is called the
“de-rotation” law on A340 and
A330. On these aircraft, as soon as
the main wheels touch the ground,
this law is engaged and helps the pilot to control the pitch attitude until
the front wheels are on ground. This
law does not exist on the A320 family
but was installed during the development of the A340 because, during
a demonstration flight, an airline
A similar law was installed on
the A380 by precaution, despite
the fact that the A380 has none of
the characteristics of the A340. In
all cases, it appeared that this law
was only engaged for two or three
seconds and therefore was probably useless. In May 2006, during
flight 221 of aircraft 1, we used the
opportunity provided by the tuning of the pitch law for approach
and landing to make the decision
to remove it, keeping the flare law
engaged during this phase. After
several landings, it appeared that
this was the right solution and from
then on, all landings were performed with this modified law in
order to be sure that there was no
adverse consequence.
Later on, some minor final adjustments were made on the approach
and flare law. The target was to
satisfy the majority of pilots! The
most important modification during this period was the increase of
pitch authority when at high weight
to reduce the risk of hard landing in
case of emergency turn back.
Part 2 will include the development of the lateral law (the
“ailerons waltz”) and the tuning of the low speeds and high
speeds protections.
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Safety
Issue 13 | January 2012
The Airbus Safety Magazine
Issue 13 | January 2012
Uwe EGGERLING
Safety Director
Engineering & Maintenance
Customer Services
3. Use of Non
Approved Aircraft
Maintenance Tools
Depending on the level of the customized maintenance program
selected, the investment in the
required Ground Support Equipment (GSE) and tools can become
significant.
Facing the Reality of
Everyday Maintenance
Operations
The aviation maintenance environment is a challenging working place.
Mechanics work in physically demanding conditions, such as high
above the ground in the aircraft
structure, or in small confined surroundings. They can be exposed to
high or low temperatures, and to
demanding shift work.
ensure good communication, diagnose and fix problems under time
pressure, read and record various
data, and continuously adapt to
new technologies.
There is an increasing workload
and time pressure to get the aircraft
back into service as quickly as possible after maintenance. Aircraft
maintenance requires mechanics
to follow procedures by the letter,
The objective is to share the lessons
learned and experience reported from
the Airbus fleet. It will also raise
awareness, and provide recommendations for safe maintenance
operations.
The Safety First magazine will
dedicate a number of articles to the
field of maintenance.
1. Introduction
Most maintenance engineers can
remember cases where the use of
a wrong, or inappropriate tool, has
contributed to difficulties in maintenance operations. In most cases,
this has lead to additional incurred
costs, but on certain occurrences
this has even represented a potential threat for the safety of maintenance personnel.
The absence of reliable statistical
figures in how often specific maintenance tools have been involved
in maintenance errors can be explained by the fact that there are no
specific reporting requirements for
maintenance events involving tools
as being at the origin of the event.
The consequences resulting from
the use of wrong, or inappropriate
tools, are not always immediately
evident in terms of aircraft dispatch
indicators, and, even when they are,
they may not have been reported as
the origin of the event.
This article will cover the subject
of tooling issues related to engine
removal and installation procedures. However, the points raised
here are illustrative as well of other
maintenance operations.
Cheap GSE/tools may be offered
from local suppliers, “round the
corner”, as substitutes for approved
or proprietary tools. These may
be copied and manufactured by
non- approved suppliers, and may
therefore not conform to the Airbus
technical specifications.
There have been instances where
tools have been made from incomplete, or out-of-date drawings, incorrect material, and/or according
to wrong protection processes. As
a consequence, it is likely that these
tools will not be of the appropriate
quality, and not perform their intended
function in a safe and satisfactory
manner.
2. Brief Events
Description
The following two events are representative of a number of similar
hazardous engine removal/ installation incidents:
Such non-approved tools can be
categorized into three main groups:
q On the first occurrence, one of
the bootstraps failed, causing an
engine to drop by a distance of
three feet (fig. 1).
Figure 1
Consequence of
failed bootstrap
q On the second event, an engine
fell to the ground during its removal.
The forward left chain pulley disengaged while the maintenance team
was performing Aircraft Maintenance Manual (AMM) subtask
71-00-00-020-053-A(fig. 2).
tools bearing the same part number,
but copied from the original by unauthorized companies.
q “Alternate” tool design sold as
so-called “equivalents”. These tools
have a part number different to the
one given in the manufacturer’s
documentation.
Use of any of the above types of
non-approved tools for maintenance could lead to aircraft or component damage and/or personnel
injury. If non-approved tools are
used, the test result may not reflect
that of the approved tool.
q Use of tools not listed in the
AMM, and not approved by Airbus.
q Not using appropriately mainq A too high pre-load applied to the
tool, which can damage the tool.
manufactured and distributed by
non-licensed companies based on
non–controlled drawings.
q Copies of Vendor proprietary
The reported problems in the use
of the engine tools (the bootstrap),
are not related to any one particular
Airbus type.The majority of these
incidents are the consequence of
one, or a combination of the following reasons:
tained tools.
q Airbus and Supplier/Vendor tools
Figure 2
consequence
of disengaged
chain pulley
Airbus therefore recommends that
Airlines and Maintenance Centers
use only the specific tools called
for in the Airbus and/or Vendor
documentation, and that users ensure
that they are built by the approved
manufacturer.
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Safety
Issue 13 | January 2012
4. Non Appropriately Maintained
Tools
Manual
hoist
The Airbus Safety Magazine
Issue 13 | January 2012
5T Electrical
hoist
A380 rear
bootstrap
structure
2T Electrical
hoist
Some GSE/tool devices require
regular maintenance to be performed, as specified by the GSE/
tool manufacturer. Adherence to
the GSE/tool maintenance instructions will contribute to a failurefree operation, and reduce the risk
of personnel injuries.
As an example, let us consider the
bootstrap (fig. 3). It consists of two
main parts:
Figure 3
A380 bootstrap
structure
q The bootstrap structure, which is
the interface between the pylon and
the lifting device. This structure
has to be periodically inspected and
tested. A visual inspection should
be done at each tool use. If any
cracks or impacts are identified, the
tool should not be further used.
Supervision
System
Figure 5
Electric
bootstrap tool
Periodical tests consist of applying
a load to the structure (125% of
the Working Load Limit for Airbus
tooling). Measurements are taken
before and after the test, and should
provide the same result. If the load
test provides different results, the
tool is damaged and should be discarded.
5. Too High
Pre-Load Applied
to the Tool
Needle
dynamometer
q The lifting phase is the operation
dedicated to lift up the engine from
the ground to the pylon. This phase
stops when the engine mounts start
to enter in the pylon shear pins.
q The lifting device (chain hoist),
which is the interface between
the structure and the assembly to
lift (the engine cradle). The lifting device is a device available on
the market. The suppliers of the
lifting device specify the maintenance recommendations to be
applied. Typically, a visual inspection should be done every time the
tool is used, and the friction brakes
should be inspected at specified intervals.
Investigations of several cases
of engine drops have determined
that the hoist maintenance had
never been done, and that the braking system was either damaged or
showed presence of oil.
The engine installation procedure
with the bootstrap system consists
of two main phases:
q The approaching phase is the operation dedicated to engage the pylon
shear pins in the engine mount and
to have contact between engine
mount and the pylon.
Figure 4
Needle
dynamometer
The bootstrap system is equipped
with needle dynamometers (fig. 4)
indicating the applied loads.The
approaching phase is sensitive because the technicians have to continuously monitor the loads applied
on the bootstrap system. Several
mechanics, working as a unit, are
required to perform this operation.
They have to ensure proper communication amongst the team in
Operator 1
Lifting Control
of the left Side
Figure 6
Operation
of electric
bootstrap
order to ensure a balanced bootstrap
movement and an adequate load
monitoring at all times. An overload
may cause a life threatening structural failure of the bootstrap.
Operator 3
Global task
overview
Operator 3
Lifting Control
of the right Side
The AMM provides the references
for the standard tool, which in combination with the described procedures ensures a safe operation during
engine removal and installation.
29
30
Safety
Issue 13 | January 2012
6. Electric
Bootstrap Tool
In addition to the standard tool
required by the AMM, Airbus has
developed a new “electrical bootstrap”
tool (fig. 5).
Safety
References
Document
Title
Recommendations
OIT
999.0063/96
A300/A310/A300-600 - Ata
54/71 - Engine dropping during
removal/installation.
Failure of hoist fittings or
bolts, caused by static
overload. This will occur
when stirrups of the rear
bootstrap beam cable jam
in pulleys. AMM tasks
modified to provide cautions associated to jamming.
OIT
999.0114/97
A340 ata 71, engine removal
installation amm procedure.
Operators reported during
engine removal engine/
cradle assembly rotated
around forward bootstrap
hoisting point. Forward is
heavier than aft, and if not
cranked correctly can end
up being in a nose down
position. AMM procedure
revised.
OIT
999.0042/00
A319/A320/A321 -ATA 71Consequences of utilizing
non-certified Airbus tooling
for engine change.
Use of another manufacture tooling, during which
one winch failed, causing
the engine to drop, causing
minor damage. Recommendations to use approved Airbus tooling.
SIL 71-020
Engine removal/installation
procedure with "bootstrap
system".
Attachment bolt failure due
to excessive shear load,
due to asymmetrical loading configuration created
by blockage of bootstrap
cable. Best practice recommendations provided to
prevent dropping of engine.
TEB number:
340A3009-2
98F71201000 021 A340
200/300 bootstrap modification
TEB number:
340A3162-2
98F71201006036 A340
500/600 bootstrap modification The previous lift from YALE
is no longer procurable for
98F71201006034 A330 GE
the bootstrap application,
bootstrap modification
it was replaced by a new
AERO ref from YALE. The
98F71201006030 A330 RR
TEB also remind the basic
bootstrap modification
maintenance to perform
on a YALE hoist.
98F71201006032A330 PW
It offers a number of enhancements,
including easier handling and improved load monitoring, and requires
less mechanics. It is therefore safer to
operate.
The main features of this new GSE
are:
q Wireless electrical hoists
q Integrated dynamometers
q A load supervision system.
The lifting control achieved for
the right and left hand side, as well
as for the forward and aft hoists
is performed by remote control
devices (fig. 6), which include integrated load control displays. A
warning system prevents any risks
of overload.
7. CONCLUSION
The use of non approved, non appropriately maintained or improperly used aircraft maintenance tools
represent safety hazards that need
to be properly addressed.
Airbus therefore recommends to:
q Use only GSE/tools specified
in the Airbus and/or Vendor documentation and to ensure that they
are built by the approved manufacturer.
TEB number:
330A3036-2
q Adhere to the GSE/tool manu-
TEB number:
330A3037-2
q Closely follow the procedures
TEB number:
330A3038-2
facturers maintenance instructions.
described in the Aircraft Maintenance Manual.
TEB number:
320A3197-2
bootstrap modification
98D71203501001 Single
Aisle bootstrap modification
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32
Safety
Issue 13 | January 2012
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The Airbus Safety Magazine
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Previous Safety First Issues
Issue 12, July 2011
– Airbus New Operational Landing Distances
– The Go Around Procedure
– The Circling Approach
– VMU Tests on A380
– Automatic Landings in Daily Operation
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– Minimum Control Speed Tests on A380
– Radio Altimeter Erroneous Values
– Automatic NAV Engagement at Go Around
Issue 10, August 2010
..............................................................................................
– A380: Flutter Tests
– Operational Landing Distances:
A New Standard for In-flight Landing Distance Assessment
– Go Around Handling
– A320: Landing Gear Downlock
– Situation Awareness and Decision Making
Post/Zip Code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Issue 9, February 2010
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– Incorrect Pitch Trim Setting at Takeoff
– Technical Flight Familiarization
– Oxygen Safety
E-mail . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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– A320: Prevention of Tailstrikes
– Low Fuel Situation Awareness
– Rudder Pedal Jam
– Why do Certain AMM Tasks Require Equipment Resets?
– Slide/raft Improvement
– Cabin Attendant Falling through the Avionics
Bay Access Panel in Cockpit
Issue 5, December 2007
– New CFIT Event During Non Precision Approach
– A320: Tail Strike at Takeoff?
– Unreliable Speed
– Compliance to Operational Procedures
– The Future Air Navigation System FANS B
Issue 4, June 2007
– Operations Engineering Bulletin Reminder Function
– Avoiding High Speed Rejected Takeoffs
Due to EGT Limit Exceedance
– Do you Know your ATC/TCAS Panel?
– Managing Hailstorms
– Introducing the Maintenance Briefing Notes
– A320: Dual hydraulic Loss
– Terrain Awareness and Warning Systems
Operations Based on GPS Data
Issue 3, December 2006
– The Runway Overrun Prevention System
– The Take Off Securing Function
– Computer Mixability: An Important Function
– Fuel Spills During Refueling Operations
– Dual Side Stick Inputs
– Trimmable Horizontal Stabilizer Damage
– Pitot Probes Obstruction on Ground
– A340: Thrust Reverser Unlocked
– Residual Cabin Pressure
– Cabin Operations Briefing Notes
– Hypoxia: An Invisible Enemy
Issue 7, February 2009
Issue 2, September 2005
– Airbus AP/FD TCAS Mode:
A New Step Towards Safety Improvement
– Braking System Cross Connections
– Upset Recovery Training Aid, Revision 2
– Fuel Pumps Left in OFF Position
– A320: Avoiding Dual Bleed Loss
– Tailpipe or Engine Fire
– Managing Severe Turbulence
– Airbus Pilot Transition (ATP)
– Runway Excursions at Takeoff
Cell phone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Issue 13 | January 2012
Issue 8, July 2009
Issue 6, July 2008
– A320: Runway Overrun
– FCTL Check after EFCS Reset on Ground
– A320: Possible Consequence of VMO/MMO Exceedance
Issue 1, January 2005
– Go Arounds in Addis-Ababa due to VOR Reception Problems
– The Importance of the Pre-flight Flight Control Check
– A320: In-flight Thrust Reverser Deployment
– Airbus Flight Safety Manager Handbook
– Flight Operations Briefing Notes
33
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