What happened
On 4 February 2011, a British Aerospace Jetstream 41, registration G-MAJD, was performing a scheduled passenger service from Teesside to Southampton via Leeds/Bradford. The flight, which included two crew members, a cabin attendant, and five passengers, encountered significant weather challenges upon arrival at Leeds/Bradford.
As the aircraft approached the airport, the crew received reports of strong, gusty winds. During the initial approach, the aircraft experienced instability and descended below the glideslope, prompting the commander to execute a go-around. The crew subsequently prepared for a second approach using a different flap setting. During the final stages of this second approach, the aircraft encountered intense wind conditions.
Upon touchdown, the commander noted that while the landing was not heavy, the aircraft experienced significant directional control difficulties, characterized by a right yaw followed by a sharp left swing. Although the aircraft vacated the runway normally, a subsequent inspection on the apron revealed damage to the left main landing gear.
The investigation
The AAIB examined the aircraft on its jacks at the airport. Investigators found that the left main landing gear was leaning outwards. An inspection of the landing gear bay revealed that the outboard trunnion pin had fractured. This failure caused the trunnion housing to press against Rib 8, damaging the structural rib and causing the landing gear doors to drop open.
Flight data recorders were analyzed, showing erratic lateral and normal accelerations consistent with heavy wind conditions. The data captured a peak normal acceleration of 1.6 g and a lateral acceleration of 0.6 g at the moment the gear parameters indicated the aircraft was no longer sufficiently compressed on the ground. Metallurgical analysis of the fractured pin confirmed there were no pre-existing material defects. The laboratory findings indicated that the failure was caused by upward loading on the outboard wheel.
Findings
- The landing was conducted in strong and gusty crosswind conditions.
- The left main landing gear outboard trunnion pin failed due to overload shear.
- The failure was caused by purely upward loading on the outboard wheel during the landing sequence.