What happened
On May 6, 2017, a LAK-17AT motor glider departed from Mannheim City Airfield (EDFM) via a winch launch. Witnesses observed the aircraft climbing toward the east. Shortly after the pilot released the tow rope, the engine was extended. According to the airfield traffic controller, the aircraft's flaps were also extended during the engine deployment process.
Approximately one minute after releasing the tow rope, the aircraft entered a steep left turn with a significant longitudinal pitch. While at an altitude of approximately 300 to 350 meters, the aircraft plummeted into a harvested field roughly 1 km east of the airfield. A witness reported that the pilot attempted to start the engine twice following the release of the tow rope, but the attempts were unsuccessful. The impact resulted in the fatal injury of the pilot and the total destruction of the aircraft.
The investigation
The BFU investigation examined the aircraft's flight data, including two portable navigation devices and a collision warning system. The investigation also reviewed the aircraft's maintenance history, noting that the engine had approximately 18 hours of total operating time and the aircraft had completed 833 total flight hours. The investigation also analyzed the engine's flight manual, which specifies critical procedures for engine extension and starting in flight.
Findings
- The engine was found in the extended position at the crash site.
- The pilot attempted to restart the engine twice after unhooking from the winch cable, but the engine failed to run.
- The engine failed to start during the critical period following the release of the tow rope.
- The flight manual specifies that engine starting/restarting should only be performed above 400 meters to allow for emergency procedures, including engine retraction if necessary.
- The aircraft was flying with extended flaps during the engine deployment phase.