Accident Summary
On 31 May 2010 at 0910 UTC, Yak-52 G-YAKH was involved in a ground incident at White Waltham Airfield, Berkshire. The aircraft was being taxied after landing on Runway 03 (grass) when the left main landing gear leg retracted, causing the left wing tip to contact the ground. The pilot shut down the engine; the aircraft sustained minor damage to the left wing tip, left aileron, and tail skid. The pilot was uninjured.
History of the Flight
The pilot had completed three successful touch-and-go landings prior to the incident. After the fourth landing, he vacated the runway to the right and began taxiing toward the fuel pumps. He reduced engine power to 40% and retracted the flaps while the aircraft slowed on an upslope. Shortly thereafter, he felt a prominent lurch to the left. He looked left and saw the left wing dropping, so he pulled the throttle back to idle and reached for the landing gear selector; in doing so, he believes he may have briefly selected it up before reselecting down. The left main gear leg retracted, and during recovery the right main gear leg also retracted. The left wing continued to drop until its wing tip hit the ground while the aircraft was rolling forward at walking speed. Because the nose gear leg and right main gear leg remained extended, the propeller did not strike the ground. After calling for assistance, ground handlers lifted the left wing, causing the right main gear leg to retract. When the aircraft was later recovered, both main gear legs were extended and locked.
Landing Gear Examination
The main landing gear legs on the Yak-52 retract forward and are operated by a pneumatic system. They do not retract into the fuselage or wings but remain protruding beneath the aircraft, protecting the underside in a gear-up landing. The maintenance organisation that recovered the aircraft carried out multiple extension and retraction tests; each time all three landing gear legs locked into the down position. A strip examination of the actuators revealed a small amount of internal corrosion, but it was not deemed sufficient to cause a malfunction of the locking mechanism.
Pilot's Assessment
The pilot concluded that the aircraft's prominent lurch to the left might have been caused by the left wheel dropping into a hole. Without any evidence of a mechanical fault, he assessed that he might have caused the gear to unlock when he reached for the landing gear selector.