What happened
The aircraft was parked on the ramp when the pilot attempted to start the engine, but the attempt was unsuccessful due to low temperatures. In an effort to loosen the engine, the pilot exited the cockpit to manually turn the propeller. He did not intend to start the engine during this process; however, he neglected to turn off the magnetos. During this procedure, the engine unexpectedly started, causing the pilot to be struck in the head and the right elbow by the propeller.
The pilot sustained two injuries to his head and right elbow.
According to the 1959 PA-24-250 Airplane Flight Manual, specific procedures are recommended for cold temperatures under 40 degrees Fahrenheit, including priming the engine with three to five strokes. The manual also notes that if conditions are extremely cold, the pilot should pull the propeller through by hand four to six times before setting the ignition key to 'left' and engaging the starter button.