Incident Overview
The airplane was involved in a ground collision with two other parked and standing airplanes. The pilot reported that the battery was insufficient to turn the engine over, so he used his car and jumper cables connected to the external jump device to start the engine. After starting, he reduced power to idle and applied the parking brake. He waited approximately thirty seconds to one minute to ensure the airplane was not capable of moving.
Sequence of Events
The pilot then left the cockpit, removed the jumper cable, and climbed onto the wing to re-enter the cockpit. While climbing on the wing, the parking brake released. The sudden movement caused him to lose his balance and fall off the wing. Before he could catch up to the aircraft, it moved forward at less than five miles per hour, clipping one aircraft near the propeller and then running into the second aircraft.
Inspection Findings
An inspection of the airplane revealed no pre-impact anomalies.