Synopsis
On 25 January 2025, a Socata TB-20 Trinidad (registration G-BSCN) experienced a landing gear malfunction during a night training flight at Blackbushe Airport. The pilot and passenger were uninjured, and the aircraft sustained abrasion to the right wingtip flap and aileron. Investigation attributed the failure to a malfunctioning electrically driven hydraulic power pack.
History of the Flight
The aircraft, operated under instruction for a night qualification, had completed a navigation exercise. Upon returning to Blackbushe, the pilot selected landing gear extension for landing. The right main and nose gear indicated down and locked, but the left main gear light remained unlit, indicating an unsafe condition. The pilot recycled the gear and attempted emergency extension procedures, but all three gear down-and-lock lights failed to illuminate. The red unlocked warning light remained on. During a low flypast, airfield staff visually assessed the gear as appearing down. The pilot then landed. Seconds after touchdown, the right main gear collapsed, causing the right wing to contact the runway and the aircraft to yaw right before stopping. No injuries occurred.
Landing Gear System
The TB-20 uses a hydraulically actuated retractable tricycle landing gear. An electrically driven hydraulic power pack provides pressure when extension or retraction is selected. Mechanical spring-loaded latches lock the gear down, with microswitches illuminating green lights when locked. A single red light warns of unlocked condition.
Cause
Examination of the landing gear system revealed that the hydraulic power pack operated sporadically, stopping and starting at random. While the emergency lowering system functioned when the gear was fully up, it was ineffective if the power pack stopped before latches engaged, leaving the gear visually down but unlocked. The malfunction was determined to be the cause of the landing gear failure.