What happened
On 1 October 2011, a Gardan GY8/80-160 Horizon, registration G-ATGY, was conducting a private local flight near Yeovilton Airfield, Somerset. Following a standard approach to Runway 09, the aircraft completed a normal touchdown on its mainwheels. Shortly after the nosewheel made contact with the runway, the nose landing gear collapsed. This caused the propeller blades to strike the ground and the aircraft to veer off the right side of the runway, eventually coming to a stop on the grass. There were no injuries to the pilot or the two passengers on board.
The investigation
The investigation examined the mechanical state of the landing gear and the cockpit controls. It was noted that the forward section of the landing gear winding handle, which is located on the control pedestal between the front seats, had detached from its mounting bracket. The aircraft's system uses a manual winding handle to operate a screw jack via bell cranks and struts. While the pilot had confirmed the gear was down via the green indicator light, the investigation focused on whether the nose leg brace strut had properly moved into the over-centre position to lock the gear.
Findings
- The nose landing gear began to collapse rearwards as the wheel was lowered onto the runway.
- The collapse of the nosewheel transmitted enough force through the control linkages to detach the forward part of the winding handle mounting bracket from the pedestal.
- As the nosewheel collapsed, the rotation of the main landing gear torque tube caused the main landing gear brace strut to move out of its over-centre position, leading to the subsequent collapse of the main gear.
- The landing gear position microswitches only indicate the position of the screw jack and do not confirm if the brace struts have fully locked into the over-centre position.