What happened
On July 10, 2017, at approximately 17:55 UTC, a Piper PA-28R-200, registration PT-DQQ, was performing a local flight at Lages Aerodrome (SBLJ) in Santa Catarina, Brazil. The aircraft, operated by Just Fly Escola de Aviação Civil Ltda. ME, was carrying two pilots and one passenger. The flight involved a series of touch-and-go maneuvers.
During the landing roll following a touchdown, the right main landing gear unexpectedly retracted. The aircraft traveled approximately 250 meters along the runway before coming to a stop on the right side of the runway, with the right wing resting on the grass. The aircraft sustained light damage, and all three occupants escaped the incident without injury.
The investigation
CENIPA investigators examined the aircraft's systems and the crew's actions. The investigation confirmed that the pilots had checked the landing gear down indicators, and the green lights had illuminated normally during the extension process. However, the investigation identified a defect in the wiring of the right main landing gear microswitch, which featured deficient insulation and a loose wire.
This loose wire was part of the circuit for the landing gear down-and-locked indication lights. Functional checks performed on the landing gear system revealed that while the locking mechanism itself was capable of maintaining the gear in the down position, the microswitch remained compressed even when the locking hook was released. This condition prevented the hydraulic pump from operating correctly, which likely led to the gear failing to lock.
Findings
- The right main landing gear retracted during the landing roll due to a malfunction in the microswitch system.
- The microswitch wiring had deficient insulation and a loose wire connected to the gear indication circuit.
- The microswitch remained in a compressed state when the locking mechanism was moved, preventing the hydraulic pump from functioning as required to secure the gear.
- The aircraft's maintenance logs for the airframe, engine, and propeller were not up to date.
- The pilots were qualified and experienced for the flight type, and the aircraft was within weight and balance limits.