Incident Overview
On 8 November 2006, a Boeing 767-2Q8, registration N330LF, was conducting a non-revenue ferry flight from Nimes to Filton Aerodrome for repainting. The flight crew consisted of two pilots, with no passengers on board. The aircraft had undergone maintenance in Nimes, during which both main landing gear units were removed, overhauled, and reinstalled. After the maintenance, the aircraft was to be ferried to Filton to be painted in the livery of the new operator.
Flight and Hydraulic Failure
During takeoff, the landing gear initially failed to retract on the first selection but retracted after reselecting the gear to UP and pressing the 'gear override' button. The flight proceeded uneventfully until the approach to Filton, when the crew decided to lower the landing gear early at approximately 8,000 ft to assess any potential issues. The gear deployed normally. After a normal landing, while leaving the runway, the flight crew observed the right hydraulic system fluid quantity and pressure decreasing. Within three minutes, right hydraulic system pressure fell to 20 psi, and the centre hydraulic system quantity and pressure also began to decline. Braking and steering remained normal until the aircraft reached its assigned stand and stopped. Ground crew noted that the left main landing gear door was missing and hydraulic fluid was leaking from the rear of the landing gear leg.
Landing Gear Door Separation
Investigation revealed that the landing gear door had separated during flight. A large portion of the door, measuring 1 x 1.7 m and weighing approximately 15 kg, was found in a garden in Chippenham, over which the aircraft had flown. The door had been released due to the failure of a castellated nut on the bolt associated with the door 'mid mount'. The door had been installed and rigged immediately prior to the ferry flight. Examination of the aircraft showed minor damage to the lower wing skins, landing gear bay, and landing gear trunnion door; visible damage was confined to steel inserts in the door attachment lugs. The lower rod remained attached to the leg, but the door had departed. Six hydraulic pipes on the rear of the landing gear leg were bent and crushed by the rod, and two hydraulic fuses for the rear brake units had operated.
Maintenance and Service Bulletins
The aircraft maintenance records indicated that only Boeing Alert Service Bulletin 767-32A0051 had been incorporated on N330LF. Subsequent service bulletins (SB 767-32-0101, SB 767-32-0146, and SB 767-32-0194) had not been applied. The maintenance organisation that performed the landing gear removal and re-installation reported difficulties in rigging the landing gear, requiring approximately ten retraction and extension cycles before achieving a satisfactory result. The work-pack confirmed that all landing gear units were removed and refitted per the Boeing Aircraft Maintenance Manual.
Flight Recorder Data
The aircraft was equipped with a solid-state flight data recorder (FDR) and a cockpit voice recorder (CVR). The FDR recorded over 100 hours of operation, including the incident, but the 30-minute CVR had overwritten the approach and landing audio. At 14:20:17, while descending through 8,000 ft, the landing gear was selected to DOWN at 249.5 kt CAS with speed brakes deployed. All landing gear legs locked down 16 seconds later. The missing door was found approximately 2 nm from the aircraft's position at gear extension, about 22 nm from the runway. Touchdown occurred nine minutes later at 127 kt. Hydraulic system pressures were around 3,000 psi at touchdown, with the right system quantity at 110%. After touchdown, the right hydraulic quantity decreased, and pressures decayed, triggering a low pressure discrete indication at approximately 1,000 psi. Centre system quantity reduced from 82% to 65% before recording ceased.
Subsequent Actions
After repairs to the brake pipes, the aircraft was flown to Nimes for replacement of the landing gear door. No further defects were reported during subsequent retraction cycles.