What happened
On 5 February 2000, an ATR42-300, registration G-ORFH, was operating a scheduled passenger flight from Teesside Airport to Paris. Shortly after departing from Runway 2/23, the aircraft climbed to 19,000 feet. Approximately 20 minutes into the flight, cabin crew notified the flight deck that a passenger had noticed a missing panel from the No 1 engine and that a noise had been heard during the takeoff roll.
Upon inspection from the flight deck, the crew observed that a portion of the No 1 engine outboard cowl door had broken off. The crew decided to return to Teesside, requesting a radar vector and limiting airspeed to 180 kt to prevent further damage. During the final approach, the crew identified the detached panel on the runway near the threshold. The aircraft landed safely without further incident, though debris from the door was found near the start of the takeoff run.
The investigation
The investigation focused on the maintenance performed prior to the flight and the physical state of the engine bay doors. The aircraft had undergone a routine weekly check the previous evening, conducted by a licensed engineer using a stepladder. This maintenance required opening the inboard and outboard cowl doors of both engines.
Examination of the aircraft revealed that the recovered panel consisted of the lower three-quarters of the left No 1 engine cowl door. The fracture was consistent with gross overload. The investigation found that the fasteners for the door's mounting beam had failed, causing the beam to pivot. The left door was found with its forward and lower latch handles in the open position. The investigation also noted that the pre-flight walk-around inspection had been performed in the dark using a torch, and the aircraft's position on the apron may have created shadows that obscured the latch status.
Findings
- The left No 1 engine cowl door was not properly secured by its latches following the previous evening's maintenance.
- During the takeoff roll, the propeller slipstream caused the unlatched door to hinge open, creating aerodynamic loads that fractured the door and its mounting beam.
- The detached portion of the door struck the aircraft, causing a split in the left wing leading edge, damage to a cabin window, and damage to the left sponson and hydraulic reservoir access door.
- The maintenance check and the subsequent pre-flight inspection were both conducted in low-light conditions, which likely prevented the detection of the unlatched handles.