Incident Overview
A pilot reported that during a pre-flight preparation, the airplane's battery appeared weak when attempting to start the engine. To facilitate an easier start, the pilot decided to manually rotate the propeller by hand one or two revolutions. This action was intended to distribute oil or lubricant to the cylinders, rings, and valve stems. The pilot informed his non-pilot passenger that he was not attempting to start the engine but rather performing a mechanical lubrication.
Sequence of Events
The pilot stated that he turned the master switch off and believed he had also turned the magnetos off. However, he did not set the parking brake or place chocks in front of the tires. After turning the propeller approximately 1 to 1.5 revolutions, the engine unexpectedly started. The airplane immediately lurched forward, and the pilot was unable to re-enter the aircraft. The unoccupied airplane then proceeded across a taxiway and a runway before encountering soft earth, where it nosed over inverted.
Damage Assessment
The accident resulted in substantial damage to the airframe. The engine was pushed aft, causing wrinkling of the fuselage. The right wing lift strut was bent, the right wing displayed wrinkles, and the aft section of the fuselage sustained bending and wrinkling. No other personnel or vehicles were involved in the occurrence.
Pilot Commentary
The pilot explained that his intention was purely to lubricate the engine manually, not to start it. He believed the magnetos were in the off position, though the subsequent engine start indicates they may have been active. The pilot also noted that the lack of parking brake or wheel chocks contributed to the aircraft's uncontrolled movement.