Pilot Injured by Propeller After Engine Unexpectedly Fires During Troubleshooting (N35083)

Incident

A pilot reported that he was unable to start the engines using normal procedures. He obtained the use of an auxiliary power unit (APU) but still could not achieve an electrical start. He then turned the magneto and master switches off and rotated the propeller backwards half a turn to check for binding; no binding was noted. Another APU start was attempted without success. The pilot then turned the magneto and master switches off again and intended to turn the propeller forward about five degrees. Upon touching the propeller, the engine fired and the propeller struck his right arm, causing a compound, multiple fracture.

Investigation Findings

The line chief stated that he and the pilot had verified that the switches were in the off position. Later, when the ignition system was checked, no discrepancies were found. Additionally, an airworthiness directive (AD) had been complied with to prevent ignition when the switch was in the off position. The starter was found to have failed (burned out).