NTSB Factual Report

On December 22, 2009, about 1215 Pacific standard time, a Beech A23-24, N973WP, collided with parked airplanes after inadvertently starting at the Grove Field Airport, Camas, Washington. The pilot, who was the owner, was operating the airplane under the provisions of 14 Code of Federal Regulations Part 91. The private pilot and passenger were not injured; the airplane sustained substantial damage. The pilot had planned to conduct a personal local area flight. Visual meteorological conditions prevailed, and a flight plan was not filed.

During a telephone conversation with a Safety Board investigator, the pilot reported that he and the passenger boarded the airplane for a local flight. Due to low overnight temperatures, when he attempted to start the engine, the starter could not turn the propeller through the entire compression cycle. As part of his normal procedure for cold weather operations, the pilot exited the airplane and rotated the propeller counterclockwise in an attempt to circulate the oil through the engine. While beginning to rotate the propeller, the engine inadvertently started. The airplane, with the passenger still on board, lurched forward and traversed across the ramp. The airplane collided with a parked airplane; the accident airplane's left wing was damaged. He noted that the master switch was off and that he had not engaged the ignition switch.

A post-accident examination of the airframe and engine by a Federal Aviation Administration (FAA) inspector and certificated airframe and powerplant mechanic revealed that there was a broken p-lead on the left magneto of the airplane. According to the pilot, the airplane last underwent an annual inspection on April 22, 2009, 41 flight hours prior to the accident. The S4LN-1227 magneto (p/n BL349365-03, s/n H139905 FR), was originally installed on the engine at time of manufacture and had amassed about 3,300 hours of time in service. The airplane was equipped with a Textron Lycoming IO-360-A2B, which rotates the propeller counterclockwise during operation (as viewed from the front).

In the section titled "RECOMMENDATION" in the NTSB Pilot/Operator Report, Form 6120.1, the pilot stated if he conducts this procedure again he will place the mixture and throttle in the idle position, chock the wheels, and turn propeller in a clockwise direction.

NTSB 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.