What happened
On 28 April 2000, a BAe 748 cargo aircraft, registration G-BVOV, was taxiing toward Runway 10 at Dublin Airport for a flight to Liverpool. During the final turn toward the holding point, the crew noted an unusual clunking sound coming from the nose gear trunnion. As the pilot attempted to correct a rightward veer by applying full left nose-wheel steering and increasing starboard engine power, the nose strut suddenly collapsed rearward under the fuselage. The nose of the aircraft struck the taxiway, causing the propellers to strike the ground. The crew immediately shut down the engines and declared a Mayday. There were no injuries to the two crew members on board, though the aircraft sustained significant damage, including bent propeller blades and damage to the nose wheel doors and fuselage skin.
The investigation
The AAIU examined the aircraft and the maintenance history of the nose undercarriage. Recent maintenance had been performed on the aircraft to repair corrosion in the nose wheel well, which required the removal and subsequent replacement of the nose landing gear leg. While technicians reported that the gear was reinstalled according to the maintenance manual, investigators discovered that the attachment pin had been installed incorrectly. Specifically, the pin was found in a position 90 degrees from its proper orientation, with the internal slots aligned in a way that allowed the securing bolt to pass through the pin's slots rather than through the intended holes in the bearing housing.
Findings
- The nose undercarriage attachment pin was improperly installed, with the slots positioned vertically rather than horizontally.
- A broken lug on the baulking device allowed the greasing plug to rotate, which prevented the securing bolt from properly anchoring the pin through the housing.
- Because the bolt only secured the baulking device and not the pin itself, the attachment pin was free to migrate out of its housing during operation.
- Ground personnel failed to follow the manufacturer's instructions regarding the verification of the attachment pin installation.
- The investigation noted that similar failures had occurred in other aircraft using the same nose gear design, including the BAe ATP.
Safety action
- The manufacturer was advised to reissue Service Bulletin 32/71 to prompt a survey of all BAe 748 aircraft to ensure the baulking device is functioning correctly.
- Instructions were recommended for the implementation of duplicate inspections during nose gear fitting to verify that slots are correctly positioned and the securing bolt passes through the proper holes.