What happened
On 26 August 2021, a Piper Seneca II (PA-34-200T), registration ZS-KFG, was conducting a multi-engine type conversion training flight from Springs Aerodrome (FASI) in Gauteng. The flight, involving a student pilot and an instructor, included simulated landing exercises in the general flying area before returning to the aerodrome.
During the final approach to Runway 21, the crew performed a landing gear cycle, noting that the green lights on the instrument panel indicated the gear was down and locked. The student pilot also verified the gear position using the side mirror. However, shortly after touching down, the nose gear collapsed. The impact caused both propellers to strike the runway, and the aircraft skidded approximately 2mm 282 metres along the surface. While the aircraft sustained substantial damage, there were no injuries to the two occupants.
The investigation
An investigation by the SACAA AIID focused on the mechanical state of the landing gear and maintenance history. Investigators discovered that during the aircraft's recovery, the main landing gears were not actually in the locked position, with the oleo strut swinging sideways. It was determined that the gear had been extended too late in the approach, preventing the locking mechanism from fully engaging.
Technical examination revealed that the nose gear down lock link assembly failed due to a fracture in the threaded section of the upper eye end, caused by extreme compression loads. The investigation also scrutinized the maintenance records of the aircraft's last periodic inspection.
Findings
- The primary cause of the nose gear collapse was that the aircraft landed with the main landing gears not in the down and locked position.
- Maintenance deficiencies were identified, as the aircraft's last inspection failed to comply with service bulletin SB 1123C and did not record essential nose gear rigging values.
- There was no documentation from the operator regarding any previous hard landings.
- The failure of the down lock link assembly was specifically attributed to a fracture caused by high compression loads during the landing sequence.