What happened
On May 9, 2001, a PA28-140 aircraft, registration ZS-EEB, was conducting circuit and landing training at FAPA. The flight involved an instructor and a student pilot. During the fourth touch-and-go procedure following takeoff, the aircraft experienced a mechanical failure. Specifically, the torque link bolt on the right-hand main landing gear failed. This failure caused the wheel and oleo assembly to detach and hang from the brake hose. As a result, the aircraft landed on the main undercarriage trunnion, leading to structural damage to the flaps, the belly skin, and the attachment area of the entrance step. There were no fatalities and no injuries reported.
The investigation
SACAA AIID examined the mechanical failure and the maintenance history of the aircraft. The investigation established that the aircraft had been maintained according to prescribed intervals, with the next major periodic inspection (MPI) not due until May 2002. The aircraft had flown 99.5 hours since its last MPI. An Approved Maintenance Organisation (AMO) inspected the wreckage and determined that the torque link bolt failure was likely the result of an overload condition caused by sideways forces applied during landings.
Findings
- The primary cause of the incident was the failure of the right-hand main landing gear torque link bolt.
- The failure was attributed to an overload condition, potentially stemming from lateral forces exerted during the landing process.
- The aircraft was being used for training purposes, which involves frequent takeoffs and landings.
Safety action
Following the accident, the AMO implemented new maintenance protocols for its fleet to prevent recurrence. These measures include inspecting the torque link bolts every 50 flying hours and mandating the replacement of these bolts every 400 flying hours, regardless of their apparent condition.