What happened
On 25 July 2011, a Cessna 441 Conquest, registration G-USAR, was performing a private flight when it experienced a significant mechanical failure during landing at Doncaster Airport. Following a standard landing, the pilot engaged reverse pitch on the propellers to decelerate. During the deceleration phase, a vibration was noted originating from the right main landing gear, which the pilot initially attributed to wheel shimmy.
Shortly after this vibration began, a loud bang was heard and the right wing dropped to contact the runway surface. This caused the aircraft to veer toward the right side of the runway, eventually coming to a halt on the grass. There were no injuries to the pilot or the two passengers on board. The aircraft sustained damage to the right wing, flaps, and landing gear, and the engine experienced shock-loading.
The investigation
Investigators examined the aircraft's maintenance history and found that the aircraft had been maintained according to the manufacturer's approved programme. A scheduled maintenance inspection conducted in May 2011 had specifically included checks of the main landing gear, and no defects were recorded at that time.
Physical examination of the aircraft revealed that the trailing arm of the right main landing gear had failed between the hinge point and the shock absorber bracket. The portion of the trailing arm assembly that remained attached to the landing gear leg had been heavily abraded by contact with the runway surface. This damage was so extensive that it obscured any potential evidence on the fracture surface that might have indicated the original cause of the failure.
Findings
- The right main landing gear trailing arm failed between the hinge point and the shock absorber bracket.
- The part of the arm attached to the wheel showed evidence of a fracture due to overload in bending.
- The initial cause of the failure could not be determined because the runway contact destroyed the features on the fracture surface.
- No corrosion was found on the external or internal surfaces of the arm.
- The aircraft had been maintained in accordance with all regulatory requirements.