What happened
On 21 April 2005, a Piper PA-34-200T Seneca, registration G-BNEN, was conducting a training flight at Oxford Kidlington Airport. After taxiing to the runway and receiving takeoff clearance, the pilot lined up on the runway and performed pre-takeoff power checks. As the throttles were advanced to reach 2,000 rpm on both engines, the nose landing gear suddenly collapsed. The impact caused significant damage to both propellers and the engines. The two crew members on board were uninjured and were able to exit the aircraft through the forward and rear doors.
The investigation
Investigators discovered that the aircraft had been involved in a separate nose landing gear collapse on 22 February 2003. While the aircraft had been repaired following that event, the investigation revealed that the damage had not been fully detected. Examination of the aircraft's structure following the 2005 incident required the disassembly of the lower forward fuselage.
Inspectors found that the lower section of the nose landing gear had shifted rearward, damaging the bulkhead and the lower nose landing gear mount. The investigation found that three rivets on the lower face of the landing gear mount had sheared, and the upper four rivets showed signs of failure. Furthermore, a crack was identified in the upper crossplate, and a crack was also found in the right-side keel beam.
Findings
- The nose landing gear collapse was caused by the progression of undetected damage to the fasteners securing the lower landing gear mount.
- The damage originated from a previous nose gear collapse in February 2003.
- Because the damage was located behind a bulkhead, there was no requirement or incentive to perform a comprehensive inspection of the internal structure during the previous repair.
- It is believed that the damage progressively worsened over time, leading to increased flexibility in the downlock mechanism, which eventually allowed the drag link to move out of its over-centre position.
Safety action
New Piper Aircraft Incorporated has confirmed it will publish amendments to all PA-34 Seneca series Aircraft Maintenance Manuals. These updates will introduce in-situ inspection procedures specifically designed to check for damage to the lower nose landing gear mount, surrounding structure, and fasteners following a nose gear collapse.