What happened
On 13 December 2005, a Scheibe SF2．5E motorglider, registration G-BHSD, was performing a private flight at the Nene Valley Gliding Club in Cambridgeshire. During the flight, the pilot shut down the engine and feathered the propeller to execute a glide landing. The aircraft crossed the airfield boundary at approximately 55 kt and completed a standard approach and touchdown, intending to stop halfway down the runway to minimize taxiing.
Following the touchdown, the aircraft appeared to decelerate much more rapidly than usual, and the pilot noted a firm sensation while moving over the ground. Upon exiting the aircraft, the pilot discovered that the monowheel landing gear had collapsed. There were no injuries to the pilot or the single passenger on board.
The investigation
The AAIB examined the aircraft and found that the monowheel landing gear had failed because the swinging arm assembly attachment points had broken away from the aircraft structure. An inspection of the failed area revealed evidence of previous weld repairs. The aircraft's maintenance records indicated that the landing gear and its surrounding structure had undergone repairs on six separate occasions since 1981 due to cracking or damage, with the most recent repair occurring in May 2000.
Detailed examination of the fracture surfaces on the attachment fittings showed surface corrosion and discoloration. These findings suggested that a crack had been present for a significant period before the final failure. The quality of the recent welding was also scrutinized, revealing issues such as excessive bead build-up, incomplete welds, and poor fusion.
Findings
- The landing gear collapse was caused by the failure of the swinging arm assembly attachment points.
- The failure was likely the result of the progression of either undetected or incompletely repaired damage.
- Evidence of previous weld repairs in the affected area indicated a history of structural issues in the landing gear assembly.
- The presence of corrosion on the fracture surfaces indicated that a crack had likely been propagating for some time prior to the accident.