What happened
On 24 May 2013, an Airbus A319-131, registration G-EUOE, was preparing for departure from London Heathrow Airport. During the flight, the crew received several warning messages, including an alert regarding an emergency exit door and the loss of the yellow hydraulic system. Shortly after takeoff, the aircraft experienced an involuntary disconnection of the autothrust and an engine fire warning.
Following the engine fire indication, the crew initiated an engine shutdown procedure. This action revealed a significant fuel leak. The flight crew subsequently conducted an approach to land at Heathrow. During the landing phase, the aircraft's braking performance was affected, and an EGPWS warning was triggered. Following the landing, the aircraft was evacuated, and there were no fatalities or injuries reported among the passengers or crew.
The investigation
Investigators examined the maintenance history of the aircraft and the actions of the ground crew. The investigation focused on the condition of the engine fan cowl doors and the procedures followed during overnight maintenance. It was established that the technicians had been performing maintenance tasks on the aircraft, including an IDG oil servicing task.
Crucially, the investigation found that the technicians had failed to follow the Aircraft Maintenance Manual (AMM) procedures for securing the fan cowl doors. Furthermore, the investigators identified an "aircraft swap error," where the technicians mistakenly returned to the wrong aircraft to complete a weekly check. Because the same technicians were working on both the incident aircraft and a different aircraft, registration G-EUXI, there was no opportunity for a second pair of eyes to detect the misidentification.
Findings
- The immediate cause of the incident was that the fan cowl doors were left unclosed and unsecured following maintenance.
- The technicians did not follow the required procedure for securing the doors when leaving the aircraft unattended.
- An aircraft misidentification occurred, leading the technicians to sign off the aircraft as serviceable after performing work on the wrong plane.
- The error was compounded by the technicians working in separate vehicles, which prevented them from cross-checking their work.
- The lack of a formal fatigue risk management system for maintenance personnel was a contributing factor, as the technicians were at an elevated risk of fatigue.
- The unavailability of specific tooling (the IDG gun) may have prompted the decision to postpone the completion of the work, contributing to the procedural lapse.