SAS flight 2748, a DHC-8-402Q Dash 8, took off from Copenhagen, Denmark, on a flight to Palanga, Lithuania. The flight proceeded uneventfully until the final approach to Palanga. At an altitude of 2000 feet, the flight crew selected the landing gear down. However, the right-hand main gear extended but did not lock down and the landing gear doors did not close. The approach was aborted and the aircraft was positioned for another approach. The landing gear was recycled, but the warning remained. The flight crew decided to divert to Vilnius Airport. Before landing at Vilnius, another attempt was made to release the undercarriage using a backup system, but the undercarriage control panel still showed unsafe the same warnings. The no.2 (right) engine was shut down and the propeller was feathered prior to landing at Vilnius. When the plane touched down, right-hand main gear automatically retracted after a second. The no.1 engine was shut down and the aircraft slid off the side of the runway and stopped about 40 m to the right of the runway at 1150 m from the runway threshold. Cause The aircraft accident was caused by the separation of the piston rod of the extension/retraction actuator from the rod end during right hand main landing gear extension due to thread connection corrosion. The freely falling landing gear broke the apex hinge lugs of the stabilizer sections, the right hand landing gear did not lock in the extended position and collapse occurred when the aircraft was rolling after landing.