BEECH A23-24 near Camas, WA — 2009-12-22

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 narrative

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.

Analysis

Primary failure mode

Human factors

First missed decision gate

Pilot could have ensured the engine was secured before attempting to rotate the propeller.

NTSB coding

• Electrical system malf/failure · Prior to flight

Evidence available

• 1 docket document

Docket documents1

• Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1form

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