What happened
On June 28, 1966, a twin-engine Cessna 310 B, registration HB-LBD, was forced to perform an emergency landing at Grenchen airport. The necessity for the aborted flight was driven by a technical malfunction that required the pilot to manually extend the landing gear during the approach.
Following the landing, the aircraft was positioned in front of a hangar. During this time, the battery/accumulator was replaced. As the aircraft began to taxi away from its parking position, the landing gear collapsed.
The investigation
Investigators examined the circumstances surrounding the gear collapse and the preceding technical failure. The inquiry focused on the state of the landing gear mechanism after the battery replacement and during the subsequent movement of the aircraft.
Findings
Technical analysis revealed that the landing gear had been unlocked while the aircraft was stationary. This unlocking was the result of a manual error or incorrect manipulation performed by the flight instructor. Because the gear was not properly secured, it could not support the weight of the aircraft during taxiing, leading to the structural failure of the gear assembly.