Beech A23-24 N973WP accident near Camas, Washington

Probable cause

The left magneto's broken p-lead, which led to the engine inadvertently starting while the pilot was turning the propeller by hand.

NTSB analysis

The pilot reported that due to low overnight temperatures the engine would not start. As a part of his normal procedure for cold weather operations, he turned off the master and ignition switches, removed the key, and exited the airplane. The pilot was rotating the propeller counterclockwise by hand when the engine suddenly started. The airplane began moving down the taxiway and struck an unoccupied, parked airplane. The engine immediately stopped and the airplane turned approximately 90 degrees to the left, substantially damaging the airplane's left wing. Postaccident examination of the engine revealed a broken p-lead on the left magneto of the airplane. The pilot stated that he could have prevented this accident from occurring by placing the mixture at idle cutoff, placing the throttle at idle, chocking the wheels, and turning the propeller in a clockwise direction.

Text from the NTSB. Open the NTSB docket for WPR10LA091 for the full record.