Undetected engine thrust reverser deactivation in Airbus A320 in Australia
Topics: AUSTRALIA AIRBUS
The aircraft was operating as a scheduled passenger flight, from Adelaide, South Australia.
After a normal descent and touchdown, the captain selected both engine thrust reversers. The left engine thrust reverser did not activate. The aircraft decelerated using normal braking and taxied to the gate without further incident.
There was no damage to the aircraft, or injuries as a result of the incident, and the captain reported the thrust reverser issue for investigation.
The ATSB found that during overnight maintenance in Adelaide, the left engine thrust reverser lockout pin had been installed. However, the pin was not removed after the maintenance, resulting in the aircraft returning to service with the thrust reverser deactivated.
The lockout pin was located at the top of the engine and its 1 m red warning flag was difficult to see in the prevailing low-light conditions. This probably led to the engineer not seeing the flag and removing the pin.
Further, the lockout pin was not booked out of the tool store nor was its installation recorded in the technical log. As a result, the checks that these procedures provided to ensure the pin's removal were missed.
The aircraft’s maintenance organisation, Qantas, advised that it is taking safety action that includes the following:
- Highlighting the importance of the aircraft maintenance manual precautions to maintenance staff at Adelaide.
- Lengthening all thrust reverser lockout pin warning flags to hang past the closed engine cowls. The pin will also have a warning notice attached for placement on the engine thrust reverser controls during maintenance.
The aircraft manufacturer, Airbus, advised that the August 2019 revision of the aircraft maintenance manual introduced an operational test of the thrust reverser system to confirm its re-activation after maintenance tasks.
This investigation highlights the importance of considering the environmental conditions in which equipment and tools will potentially be used, as well as the importance of following procedures that in this instance should have resulted in detecting the error.
When considering the effectiveness of equipment, tooling and procedures that aim to minimise the likelihood and/or consequences of an error, an engineered solution is generally more effective than relying on procedural compliance.
Further, a functional check is generally more effective within procedural compliance than a self-check of work. ■