What happened
On 3 January 2022, a Beechcraft 200, registration G-GHSV, was performing a private positioning flight from Lydd to Alderney. During the approach to the original destination, the pilot selected the landing gear down but noted that the green indicator light for the left main landing gear failed to illuminate. After verifying the bulb was functional and attempting to cycle the gear again with the same result, the pilot initiated a go-around and diverted to Exeter Airport, where the aircraft was regularly maintained.
While en route to Exeter, the pilot declared a MAYDAY due to the unsafe gear indication. Before landing, the pilot performed a flypast of the Exeter tower, where ground observers confirmed that the left main landing gear was indeed in the down position. During the landing roll on Runway 26, the left main landing gear collapsed. The pilot attempted to maintain control by holding the left wing up, but the aircraft's belly pod, gear doors, and flaps eventually made contact with the runway, and the left propeller tips struck the surface. There were no injuries to the pilot.
The investigation
The AAIB examined the aircraft after it was recovered to a maintenance facility. Upon jacking the aircraft, the left main landing gear lowered under gravity, revealing a failed actuator shaft near the rod end clevis. The investigation found that the down-lock mechanism was damaged and missing the hook and lever attachment from the notched hook.
Laboratory analysis of the removed actuator showed that the shaft had buckled at its thinnest section and had bent where it exited the actuator body. Additionally, the actuator trunnions had fractured. The fractures on the down-lock notched hook were determined to have occurred due to sheer overload, with no signs of prior cracking.
Findings
- The left main landing gear down-lock mechanism failed to fully engage, meaning the gear was in an unlocked state during landing.
- The left main landing gear down-lock system had likely lost its rigging adjustment, preventing the hook from fully engaging with the locking plate.
- Because the hook did not reach the indicator switch, the cockpit green light failed to illuminate.
- Upon touchdown, the unlocked drag brace began to fold, which forced the locking plate through the partially engaged hook and caused the hook to fracture.
- The folding drag brace placed excessive load on the actuator, leading to the buckling of the actuator shaft and the subsequent collapse of the gear.