What happened
On July 2, 2019, a Piper PA-34-200T Seneca II, registration G-BOUM, was conducting an instructional flight at Cascais Airport (LPCS), Portugal. The flight, operated by O.A.T.C., involved a student pilot and an instructor performing a training lesson that included emergency landing gear extension procedures and circuit patterns.
After completing the planned maneuvers, the crew returned to the airfield for normal operations. Following a successful first touch-and-go, the crew proceeded to a second touch-and-go. During the landing roll of the second circuit, as the student pilot retracted the flaps to prepare for the subsequent takeoff, the nose landing gear collapsed. The aircraft's forward section and propellers struck the runway, causing substantial damage to the lower fuselage and propellers. The occupants were uninjured, and the instructor successfully stabilized the aircraft on the runway.
The investigation
The GPIAAF investigation examined the aircraft's maintenance history and mechanical condition. The aircraft, which had approximately 16,050 flight hours, had recently undergone nose landing gear maintenance on June 19, 2019, and had completed 42 landings since that service.
During technical assessments in the operator's hangar, investigators observed that the nose landing gear retracted again when the aircraft was lowered from its jacks, even without a command. Detailed analysis of the mechanism revealed excessive clearances in the down-locking system, specifically within the down-lock rod. The investigation also noted that while there were previous reports of noise during gear extension, these issues had not been recorded in the aircraft's technical log.
Findings
- The primary cause of the nose landing gear failure was a failure of the overcenter mechanism.
- Contributing factors included the incorrect adjustment of the nose landing gear down-lock rod.
- Excessive wear was present on major components of the down-locking system, which had not been detected during maintenance.
- The use of the landing gear free-fall (emergency) method during the preceding training lesson, while permitted, is not the manufacturer's preferred method of operation.
Safety action
- The GPIAAF issued safety recommendation PT.SIA 2019-006 to the operator, ATO OMNI Aviation Training Center, Lda., requiring an evaluation of their aircraft technical logbook system. The goal is to improve the implementation and use of defect reporting by pilots to ensure maintenance corrective actions effectively maintain aircraft design specifications.