Incident Overview
A pilot was seriously injured when a radial engine started unexpectedly while he was hand-propping it. The incident occurred after a flight delay prompted concerns about potential hydraulic lock.
Pre-Start Preparations
The pilot had completed the 'before starting engines' checklist prior to departure. Due to a delay, the pilot became concerned about oil accumulating in the lower cylinders of the radial engine, which could cause internal damage during engine start from hydraulic lock. To mitigate this, he decided to clear the oil by manually rotating the propeller.
Hand-Propping Attempt
The pilot left the cockpit and rotated the propeller by hand. The engine started instantly, and the force threw the pilot to the ground, resulting in serious injuries.
Post-Accident Examination
According to the pilot, an examination of the cockpit after the accident revealed that the magneto switch was still in the 'on' position.