On April 5, 1990, a Stinson 108-2 (registration N9443K) was involved in an aviation accident near Hillsboro, OR. Investigators recorded the probable cause as: PILOT DISPLAYED POOR STARTING PROCEDURES BY PROCEEDING WITH KNOWN DEFICIENCIES WITH THE PARKING BRAKE AND THE INADEQUACIES OF THE TIE DOWN. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A pilot reported that after hand-propping the engine, the aircraft overrode the parking brake and broke its tie-down chain, then collided with two parked aircraft.
Incident Details
According to the pilot's report, before attempting to start the engine, he secured the tail of the airplane with a tie-down chain, set the parking brake, and adjusted the throttle to 550 RPM. He then proceeded to hand-prop the engine. After the engine started, the pilot began to walk around the airplane, when he noticed the airplane starting to move forward.
Sequence of Events
The airplane overrode the parking brake and broke the tie-down chain. The pilot attempted to get inside the cockpit but slipped and was unable to do so. The airplane continued moving forward and eventually collided with two parked airplanes. The pilot reported that the parking brake was not sufficient to hold the aircraft, and the tie-down chain broke under the strain. The pilot's slip prevented him from re-entering the cockpit to stop the aircraft.