British Airways A319 near London on Aug 6th 2021, avionics issues
Last Update: June 18, 2022 / 17:08:35 GMT/Zulu time
Incident Facts
Date of incident
Aug 6, 2021
Classification
Incident
Airline
British Airways
Flight number
BA-1441
Departure
Edinburgh, United Kingdom
Destination
London Heathrow, United Kingdom
Aircraft Registration
G-DBCF
Aircraft Type
Airbus A319
ICAO Type Designator
A319
The AAIB rated the occurrence a serious incident and opened an investigation. The aircraft suffered avionics issues including unreliable position information.
On Jun 16th 2022 the AAIB released their final report concluding the probable causes of the serious incident were:
The aircraft experienced severe navigation position drift in flight. The drift was caused by abnormal vertical shock loads being transferred through the overextended NLG shock absorber to the ADIRU. The abnormal shock loads were initiated by an uneven patch repair on the runway. The NGC ADIRU is particularly sensitive to sudden vertical shock loading outside its environmental qualification envelope.
The AAIB analysed:
The aircraft suffered multiple severe IR drift events in flight which caused the autopilot and autothrust to disconnect. The events were successfully managed by the flight crew and the aircraft continued to its planned destination.
The incident was caused by a chain of events, each of which was necessary to cause the eventual outcome:
1. A slight irregularity in the runway surface induced sudden vertical shock loads into the NLG.
2. An over extended NLG shock absorber reduced its absorption effectiveness, creating an increase in the vertical forces transferred to the airframe and avionics rack housing the ADIRUs.
3. The NGC ADIRUs fitted to this aircraft (fitted to approximately 14% of the fleet) were sensitive to vertical acceleration forces outside their environmental qualification envelope which induced severe drift.
Runway surface
Following these events, the airport authority found a slightly uneven runway surface patch repair which they believe may have caused the problem. It has now replaced the repair patch.
Nose landing gear leg servicing
Information provided by one of the operators indicated that the improved servicing task and revised maintenance check introduced by the manufacturer was effective in preventing their IR drift issues. However, further occurrences with other operators indicates that the issue has not been completely resolved. The development of a dedicated LANCE to improve the servicing of the NLG shock absorber is intended to reduce potential errors during maintenance activity.
NGC ADIRU
All three of the ADIRUs were tested after the event and no faults were found. During the occurrences, the air data information remained accurate throughout the flight, ruling out ADR faults. The pilots reported that aircraft attitude displays also remained accurate indicating that the IRS gyroscopes were functioning correctly. The severe positional drift experienced was probably caused by IRS accelerometer anomalies from abnormal vertical shock loads transferred to the airframe and avionics rack.
Whilst the NGC ADIRUs performed within their qualification envelope, the shock loads encountered during operation occurred outside their Cat B qualification standard. The aircraft manufacturer commented that in hindsight, the inclusion of Cat C environmental qualification criteria during aircraft design may have avoided these severe position drift issues.
Information to flight crew When this event occurred, no specific information was available to flight crews describing the possibility of multiple IR drifts, the possible indications or how to manage the situation. The aircraft manufacturer decided that publishing such information would be detrimental.
Incident Facts
Date of incident
Aug 6, 2021
Classification
Incident
Airline
British Airways
Flight number
BA-1441
Departure
Edinburgh, United Kingdom
Destination
London Heathrow, United Kingdom
Aircraft Registration
G-DBCF
Aircraft Type
Airbus A319
ICAO Type Designator
A319
This article is published under license from Avherald.com. © of text by Avherald.com.
Article source
You can read 2 more free articles without a subscription.
Subscribe now and continue reading without any limits!
Read unlimited articles and receive our daily update briefing. Gain better insights into what is happening in commercial aviation safety.
Send tip
Support AeroInside by sending a small tip amount.
Related articles
British Airways A320 over North Sea on May 15th 2024, smoke in cockpit
A British Airways Airbus A320-200, registration G-EUYK performing flight BA-764 from London Heathrow,EN (UK) to Oslo (Norway), was enroute at FL310…
British Airways A21N at London on May 6th 2024, cabin did not pressurize
A British Airways Airbus A321-200N, registration G-NEOS performing flight BA-542 from London Heathrow,EN (UK) to Bologna (Italy), was climbing out of…
British Airways A320 at London on Apr 29th 2024, loss of nose wheel steering during turnoff
A British Airways Airbus A320-200, registration G-EUUD performing flight BA-1455 from Edinburgh,SC to London Heathrow,EN (UK), landed on Heathrow's…
British Airways A388 at Singapore on Apr 22nd 2024, weather radar failure
A British Airways Airbus A380-800, registration G-XLED performing flight BA-12 from Singapore (Singapore) to London Heathrow,EN (UK), was climbing…
British Airways A320 at Milan on Apr 4th 2024, engine shut down in flight
A British Airways Airbus A320-200, registration G-EUYD performing flight BA-568 from London Heathrow,EN (UK) to Milan Linate (Italy), was on approach…
Newest articles
Singapore B773 near Bangkok on May 21st 2024, severe turbulence kills one and injures 37
A Singapore Airlines Boeing 777-300, registration 9V-SWM performing flight SQ-321 from London Heathrow,EN (UK) to Singapore (Singapore) with 211…
ANA B788 near Okinawa on May 18th 2024, engine overheating
An ANA All Nippon Airways Boeing 787-8, registration JA811A performing flight NH-468 from Okinawa to Tokyo Haneda (Japan) with 323 people on board,…
Subscribe today
Are you researching aviation incidents? Get access to AeroInside Insights, unlimited read access and receive the daily newsletter.
Pick your plan and subscribePartner
A new way to document and demonstrate airworthiness compliance and aircraft value. Find out more.
ELITE Simulation Solutions is a leading global provider of Flight Simulation Training Devices, IFR training software as well as flight controls and related services. Find out more.
Your regulation partner, specialists in aviation safety and compliance; providing training, auditing, and consultancy services. Find out more.
AeroInside Blog
Popular aircraft
Airbus A320Boeing 737-800
Boeing 737-800 MAX
Popular airlines
American AirlinesUnited
Delta
Air Canada
Lufthansa
British Airways