What happened
On 6 October 2007, a Cessna R182 Skylane RG, registration G-BOWO, was conducting a private flight approaching Wolverhampton (Halfpenny Green) Airfield. During the approach, the pilot selected the landing gear down but failed to receive the required green 'down and locked' indication.
In an attempt to rectify the situation, the pilot cycled the gear and utilized the manual hydraulic pump. The pilot also performed specific aerodynamic manoeuvres, including roll and pitch movements, to try and dislodge the gear. Despite these efforts, the left main landing gear remained partially retracted. The pilot subsequently performed a landing on the grass Runway 10. During the rollout, the left wing dropped, causing the aircraft to depart the runway and come to rest on the side of the adjacent tarmac Runway 10. There were no injuries to the pilot or the two passengers, though the aircraft sustained damage to the tailplane and the left main landing gear.
The investigation
The investigation involved a review of the aircraft's maintenance history and a metallurgical examination of the landing gear components. Investigators noted that the aircraft had previously experienced a hard landing in September 2006, though no specific inspection of the main landing gear pivot assembly was performed following that event. Additionally, there had been recent reports of unidentified hydraulic fluid loss from the right brake.
Upon recovery of the aircraft, the actuator assembly was removed, revealing that the area was saturated with brake fluid, although no leak was found originating from the gear actuators themselves. Metallurgical analysis of the detached pivot assembly focused on the area of the splined shaft.
Findings
- The investigation established that the separation of the landing gear pivot assembly was caused by a cyclic fatigue mechanism occurring during normal service operations.
- The fracture originated at the edge of the fracture face, near a lubricating hole.
- The failure of the splined shaft made the mechanical extension of the landing gear impossible.
- The aircraft's history included a previous hard landing that had not triggered a pivot assembly inspection.