What happened
On April 29, 2019, a privately owned Glaser-Dirks DG-500M motor glider, registration JA2500, was conducting a recreational flight near Iwami Airport. The flight, which included a pilot and one passenger, initially involved an engine-off gliding segment intended to provide the passenger with a gliding experience. During this phase, the pilot had retracted the engine and propeller into the fuselage.
While circling near Masuda City, the pilot encountered strong southerly winds and decided to return to the airport. Following standard procedures, the pilot extended the engine and main landing gear at approximately 1,70/0 ft. However, despite three separate attempts to restart the engine, the propeller only moved slightly before stopping, and the engine failed to ignite. Because the engine and propeller could not be retracted into the fuselage, the aircraft experienced significant aerodynamic drag.
As the aircraft approached the airport, the pilot attempted to manage the descent by pitching the nose down to gain airspeed and then up to clear a guard rail. To avoid the runway due to the extended landing gear, the pilot attempted to land on a grass area on the south side of the airfield. During a right-hand turn to avoid departing the airport grounds, the right wing tip struck the ground. The aircraft subsequently spun and came to rest with a fractured aft fuselage.
The investigation
The JTSB investigation focused on why the engine failed to restart and why the aircraft's altitude was insufficient for a safe landing. Investigators examined the aircraft's starter system, the fuel system's primer valve, and the meteorological conditions at the time of the accident. The investigation also reviewed the aircraft's maintenance history, noting that the engine had been difficult to start during ground inspections following a four-year period of storage.
Findings
- The investigation determined that the starter system was inoperative, which prevented the engine from restarting and left the engine and propeller in an extended position.
- The extended engine and propeller created substantial drag, which, combined with strong headwind conditions, caused the aircraft to lose altitude rapidly.
- The pilot entered the airport at a very low altitude, making the aircraft vulnerable to ground contact during the landing maneuver.
- While an unstable primer valve was noted, the primary cause of the engine failure was the failure of the starter system, though the specific component failure (starter motor, limit switch, or DEI) could not be definitively identified as the system functioned normally during post-accident testing.