What happened
On February 12, 1971, a Mooney M-20E, registration HB-DET, was involved in an accident at Birrfeld airfield during a pilot's initial solo flight as part of a transition training program. Following a landing at approximately 17:09, the pilot attempted a go-around maneuver. During this process, the landing gear collapsed, causing the aircraft to perform a belly landing on the grass runway. The pilot sustained minor injuries, specifically to the back of the hand, while attempting to restrain the moving gear lever. The aircraft sustained damage estimated at 30% of its total value, though no third-party property was affected.
The investigation
Investigators examined the mechanical components of the manually operated landing gear system and found all parts to be intact and functional. While a slightly low preload was noted in the nose gear compression strut, this was determined to be irrelevant to the accident. The gear handle locking mechanism and the safety latch were both found to be in proper working order. Additionally, the landing gear warning horn and the cockpit indicator lights were fully operational. The investigation also noted that the pilot had not fully returned the throttle to the idle position, which prevented the warning horn from sounding.
Findings
The investigation established that the primary cause of the accident was pilot error regarding the gear lever position. It is believed that the landing gear lever was not properly secured or locked into position prior to the go-around. The pilot admitted to not monitoring the landing gear indicator lights following the final pre-landing check. The collapse occurred after the aircraft had traveled approximately 200 meters along the uneven grass runway.