What happened
On April 22, 1997, at approximately 19:17 local time, a Jakovlev 52, registration LY-AIX, was involved in an accident at Alytus Aerodrome. The aircraft, operated by Alytus Aeroklubas, was performing circuit flights with a group of Finnish pilots. Following several instructional circuits, the pilot was permitted to fly independently.
The pilot performed pre-flight preparations and engine start without instructor supervision. After taking off from the aerodrome, the flight proceeded normally through two circuits. Prior to the third circuit, the pilot notified the air traffic controller of intentions to land and received clearance. The landing was executed as a three-point landing; however, upon touchdown, the nose landing gear strut began to retract.
As the aircraft continued along the runway, the propeller made contact with the ground approximately 35 meters from the touchdown point. The engine subsequently struck the ground, and the aircraft finally came to a halt 80 meters from the initial touchdown point. The accident resulted in significant damage to the propeller, engine frame, exhaust pipes, and various engine components, though no injuries were reported.
The investigation
The investigation examined the sequence of events leading to the gear retraction and the state of the aircraft following the incident. Investigators noted a discrepancy between the pilot's statement—which claimed the landing gear was extended and indicated by three green lights—and physical evidence at the scene, which suggested the nose wheel touched down approximately 0.8 meters before the main wheels.
Furthermore, while it could not be definitively proven whether the pilot had closed or opened the air system valve during post-flight procedures, investigators noted that the valve was found in the open position after the accident. Testing of the landing gear retraction and locking mechanism on jacks showed that the system functioned correctly without mechanical failure or structural breakage in the struts or locking pins.
Findings
The investigation could not establish an indisputable cause for why the nose landing gear strut began to retract upon touchdown. However, based on the analysis of pre-flight procedures and historical operational data for the Jak-52, the commission concluded that the retraction was likely caused by the engine start, taxi, and subsequent flight being conducted with the air system valve closed.