Boeing B787-8, ET-AOP.

182 Pages·2015·4.35 MB·English

AIRCRAFT ACCIDENT REPORT 2/2015
A AIB
Air Accidents Investigation Branch
Report on the serious incident to
Boeing B787-8, ET-AOP
London Heathrow Airport
on 12 July 2013

AIRCRAFT ACCIDENT REPORT 2/2015
Air Accidents Investigation Branch
Report on the serious incident to
Boeing B787-8, ET-AOP
London Heathrow Airport
12 July 2013
This investigation has been conducted in accordance with
Annex 13 to the ICAO Convention on International Civil Aviation,
EU Regulation No 996/2010 and
The Civil Aviation (Investigation of Air Accidents and Incidents) Regulations 1996.
The sole objective of the investigation of an accident or incident under these Regulations
is the prevention of future accidents and incidents. It is not the purpose of such
an investigation to apportion blame or liability.
Accordingly, it is inappropriate that AAIB reports should be used to assign fault or blame
or determine liability, since neither the investigation nor the reporting process has been
undertaken for that purpose.
© Crown Copyright 2015
This report contains facts which have been determined up to the time of publication. This
information is published to inform the aviation industry and the public of the general
circumstances of accidents and serious incidents.
Extracts may be published without specific permission providing that the source is duly
acknowledged, the material is reproduced accurately and it is not used in a derogatory manner
or in a misleading context.
Published 19 August 2015
Printed in the United Kingdom for the Air Accidents Investigation Branch
ii
Department for Transport
Air Accidents Investigation Branch
Farnborough House
Berkshire Copse Road
Aldershot
Hampshire GU11 2HH
July 2015
The Right Honourable Patrick McLoughlin
Secretary of State for Transport
Dear Secretary of State
I have the honour to submit the report on the circumstances of the serious
incident to Boeing B787-8, registration ET-AOP at London Heathrow Airport on
12 July 2013.

Yours sincerely
Keith Conradi
Chief Inspector of Air Accidents
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Air Accident Report: 2/2015 ET-AOP EW/C2013/07/01
Contents
Introduction ......................................................................................................................1
Summary ..........................................................................................................................1
1 Factual information ................................................................................................4
1.1 History of the event .........................................................................................4
1.2 Injuries to persons ..........................................................................................4
1.3 Damage to aircraft .........................................................................................4
1.4 Other damage ................................................................................................5
1.5 Personnel information .....................................................................................5
1.6 Aircraft information ..........................................................................................6
1.6.1 General information .........................................................................6
1.6.2 Aircraft description ...........................................................................6
1.6.3 Emergency Locator Transmitter (ELT) information ...........................6
1.6.4 ELT battery information .....................................................................8
1.6.4.1 General ..........................................................................8
1.6.4.2 Battery pack construction .............................................9
1.6.4.3 Positive Temperature Coefficient (PTC) protective device 10
1.6.4.4 Cell construction ...........................................................12
1.6.4.5 Cell separator ............................................................14
1.6.5 Aircraft structure ............................................................................14
1.6.6 Cabin environment ..........................................................................15
1.7 Meteorological information ............................................................................15
1.8 Aids to navigation .........................................................................................16
1.9 Communications ..........................................................................................16
1.10 Aerodrome information .................................................................................16
1.11 Flight recorders .............................................................................................16
1.12 Aircraft examination ......................................................................................17
1.12.1 Initial aircraft examination ...............................................................17
1.12.2 Aircraft structural examination .......................................................19
1.12.2.1 Initial examination .......................................................19
1.12.2.2 Detailed examination ....................................................21
1.12.3 Examination of the ELT ..................................................................22
1.12.3.1 Initial examination .........................................................22
1.12.3.2 Computed tomography (CT) examination of ELT .........23
1.12.2.3 Removal of ELT battery ...............................................24
1.12.3.4 Detailed teardown examination of ELT .........................26
1.12.3.5 Forensic examination ..................................................27
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1.12.4 Examination and disassembly of ELT battery and cells .................30
1.12.4.1 General .........................................................................30
1.12.4.2 CT examinations of ELT battery and cells ....................30
1.12.4.3 Visual examination of the battery and cells .................32
1.12.4.4 Disassembly of battery pack.........................................32
1.12.4.5 Disassembly of cells .....................................................33
1.12.4.6 Forensic examination of cell cans ................................36
1.13 Medical and pathological information ............................................................36
1.14 Fire ................................................................................................................36
1.14.1 General ..........................................................................................36
1.14.2 Propagation of the fire ....................................................................36
1.15 Survival aspects ...........................................................................................38
1.15.1 General ...........................................................................................38
1.15.2 Cabin crew and flight crew fire fighting ..........................................39
1.15.2.1 Firefighting equipment ..................................................39
1.15.2.2 B787 Flight Attendant Manual ......................................41
1.15.2.3 ELT battery fire fighting .................................................42
1.15.2.4 Rescue and Fire Fighting Service (RFFS) information. ...42
1.15.3 Toxicity ...........................................................................................43
1.16 Tests and research ........................................................................................44
1.16.1 ELT fault tree ...................................................................................44
1.16.2 ELT circuit analysis .........................................................................45
1.16.3 Manufacturers’ Root Cause testing .................................................46
1.16.3.1 General .........................................................................46
1.16.3.2 Single-cell tests ...........................................................46
1.16.3.3 Battery-level external short-circuit tests........................47
1.16.3.4 External short-circuit test on batteries installed in
an ELT .........................................................................49
1.16.3.5 Battery drain tests ........................................................56
1.16.3.6 ELT battery toxicity ......................................................57
1.16.3.7 Instrumar PTC testing ..................................................58
1.16.4 Boeing thermal propagation modelling ..........................................63
1.16.5 Calorimeter tests .............................................................................67
1.16.5.1 General ........................................................................67
1.16.5.2 Specific heat capacity test ...........................................67
1.16.5.3 Battery discharge tests .................................................67
1.16.6 Aircraft structural testing and modelling ........................................70
1.16.6.1 General .......................................................................70
1.16.6.2 Skins and stringers .......................................................71
1.16.6.3 Frames ........................................................................73
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1.16.6.4 FTIR test results ...........................................................74
1.16.6.5 Thermal modelling ........................................................77
1.16.6.6 Structural modelling .....................................................80
1.17 Organisational and management information ...............................................82
1.18 Additional information ...................................................................................82
1.18.1 Failure modes and design considerations of lithium-metal batteries ..82
1.18.1.1 Failure modes of lithium-metal batteries.......................82
1.18.1.2 Design considerations and safety features of
lithium-metal batteries .................................................83
1.18.1.3 Cell internal resistance .................................................83
1.18.1.4 Cell imbalance and voltage reversal ...........................83
1.18.1.5 Balanced packs ...........................................................84
1.18.2 Additional information on the PTC .................................................85
1.18.2.1 Installation guidance for the PTC .................................85
1.18.2.2 PTC testing ...................................................................85
1.18.2.3 Selection of the PTC for the ELT battery ......................85
1.18.3 Manufacture of the ELT battery ......................................................86
1.18.3.1 General .........................................................................86
1.18.3.2 Cathode manufacture ...................................................86
1.18.3.3 Cell assembly ...............................................................87
1.18.3.4 Cell acceptance testing ...............................................87
1.18.3.5 Battery assembly ..........................................................88
1.18.3.6 Battery acceptance tests .............................................88
1.18.4 ELT battery internal energy ............................................................88
1.18.5 Previous events .............................................................................89
1.18.5.1 RESCU 406AFN ELT wiring anomalies .......................89
1.18.5.2 Other ELT battery events .............................................91
1.18.6 ELT case resistance ........................................................................91
1.18.7 Battery and ELT certification and system safety .............................92
1.18.7.1 Technical Standard Orders ..........................................92
1.18.7.2 ELT certification requirements .....................................92
1.18.7.3 Battery certification requirements .................................92
1.18.7.4 Development and certification history of
the RESCU 406AF/AFN ELT and ELT battery ..............96
1.18.7.5 Ultralife qualification tests for TSO-C142 approval .......97
1.18.7.6 Honeywell ELT qualification tests for TSO-C91a and
SO-C126.......................................................................98
1.18.7.7 Boeing ELT certification process for the B787 ..............98
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1.18.8 Previous Safety Recommendations and safety actions ...............102
1.18.8.1 Safety Recommendations issued in
AAIB Special Bulletin S5/2013 ..................................102
1.18.8.2 Safety actions by industry ..........................................102
1.18.8.3 Safety actions by regulatory bodies ...........................103
1.18.8.4 FAA response to Safety Recommendations from
AAIB Special Bulletin S5/2013 ..................................104
1.18.8.5 Safety Recommendations issued in AAIB
Special Bulletin S4/2014 ...........................................104
1.18.8.6 FAA response to Safety Recommendations (2014-020
to -024) in AAIB Special Bulletin S4/2014 .................105
1.18.8.7 Additional FAA safety actions ....................................106
1.18.9 Aircraft structure certification information ......................................107
1.18.9.1 Certification requirements...........................................107
1.18.9.2 Flammability certification tests ...................................109
1.18.9.3 Composite flammability testing ...................................109
2. Analysis ..............................................................................................................111
2.1 General .......................................................................................................111
2.2 ELT and battery examination .....................................................................111
2.2.1 Identification of external short circuit .............................................111
2.2.2 Battery examination and possible failure sequence .......................112
2.3 Pinched wires ...............................................................................................113
2.4 Root Cause testing ......................................................................................114
2.4.1 General .........................................................................................114
2.4.2 External short-circuit tests .............................................................114
2.4.3 Cell voltage reversal .....................................................................115
2.4.4 Nature of the short-circuit ..............................................................116
2.4.5 Positive Temperature Coefficient device (PTC) .............................117
2.4.5.1 General .......................................................................117
2.4.5.2 Discharge current insufficient to trip the PTC ............117
2.4.5.3 PTC bypassed or shorted ............................................118
2.4.5.4 PTC reset ....................................................................118
2.4.6 Summary of battery failure scenarios ...........................................119
2.4.7 External short-circuit protection ....................................................121
2.5 Calorimeter tests .........................................................................................124
2.6 Certification aspects ....................................................................................125
2.6.1 DO-227 General ............................................................................125
2.6.2 DO-227 guidance and requirements .............................................125
2.6.3 TSO process .................................................................................128
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