Primary finding
Probable cause
The pilot’s inadequate engine hand propping procedure resulting in the unoccupied airplane’s unintended movement and subsequent impact with a hangar.
Investigator assessment
Analysis narrative
The airplane was not equipped with an electrical system and the engine was started by hand propping. The pilot reported that he did not have a passenger to hold the brakes in the cockpit during engine start, nor did he use wheel chocks and/or tether the tail to a fixed object because he thought using the airplane’s parking brake would keep the airplane stationary after the engine had started. Before the engine was hand propped, the pilot set the throttle about ¼” to ½” forward of the idle position, but the engine’s speed was much higher than he had expected after the engine started. The unoccupied airplane initially moved forward before it entered a left turn on the ramp in front of a row of hangars. Although the pilot was able to reach into the cockpit to move the throttle to idle, the airplane continued in the left turn and struck a closed hangar door, resulting in substantial damage to the right wing. The pilot did not report any mechanical malfunctions with the airplane that would have precluded normal operation.