What happened
On 12 January 2008, a private flight involving a Piper PA-24-250 aircraft, registration G-TALF, departed Tatenhill Airfield for Caernarfon. Shortly after takeoff, the pilot identified a failure in the electronic horizontal situation indicator. Upon attempting to reset the avionics, the aircraft experienced a total loss of electrical power, and the ammeter indicated that the battery was no longer charging.
With no electrical power available to communicate with air traffic control or verify the gear position via cockpit lights, the pilot initiated the emergency landing gear lowering procedure. During this process, the pilot heard a mechanical sound and, lacking visual confirmation, believed the gear was locked. The pilot performed a low-level circuit of the airfield and attempted a landing. While the touchdown was initially normal, the landing gear collapsed during the ground roll. The aircraft slid approximately 100 metres along the runway, eventually exiting the left edge and striking a runway light before coming to rest on soft ground. There were no injuries to the pilot or the passenger.
The investigation
An investigation into the mechanical failure revealed that the aircraft's alternator circuit breaker had tripped, leaving the electrical systems to rely solely on the battery. As the battery voltage depleted, there was insufficient power to complete the gear deployment.
Technical examination of the landing gear mechanism determined that the electric motor remained connected to the operating mechanism during the landing. It was established that the electrical release arm had not been moved sufficiently forward to fully disengage the motor. This prevented the pilot from being able to move the emergency extension lever to its fully forward position, leaving the gear in an unlocked state.
Findings
- The primary cause of the landing gear collapse was that the landing gear was not down and locked at the time of touchdown.
- An electrical fault caused the alternator circuit breaker to trip, depleating the battery.
- The electrical motor release arm had not been moved far enough forward to disconnect the motor from the gear mechanism.
- The failure of the motor release arm to fully disengage prevented the manual emergency extension lever from being operated correctly.