N4584HPiper PA-17 · 1948

The pilot reported that he attempted to hand prop the unoccupied and unchocked airplane, but was unsuccessful. He returned to the cockpit to prime the engine, but then decided to instruct his passenger on how to enter and exit the cockpit, which she then practiced multiple times before exiting the airplane to watch the start procedures again. The pilot further reported that he attempted to hand prop the airplane a second time and the engine started and accelerated to a high revolution per minute (RPM) setting. The pilot was unable to restrain the airplane by holding the right wing lift strut and the airplane made a right circle, entered a wooded area, and impacted trees.

The airplane sustained substantial damage to the wings and fuselage.

The pilot later reported that the airplane was not equipped with a parking brake.

The pilot reported that there were no preimpact mechanical failures or malfunctions with the airframe or engine that would have precluded normal operation.

Federal Aviation Administration's Airplane Flying Handbook, FAA-H-8083-3A, contains a section titled "Hand Propping" which states:

An engine should not be hand propped unless two people, both familiar with the airplane and hand propping techniques, are available to perform the procedure. The person pulling the propeller blades through directs all activity and is in charge of the procedure. The other person, thoroughly familiar with the controls, must be seated in the airplane with the brakes set. As an additional precaution, chocks may be placed in front of the main wheels. If this is not feasible, the airplane's tail may be securely tied. Never allow a person unfamiliar with the controls to occupy the pilot's seat when hand propping. The procedure should never be attempted alone.