Event Description
The pilot and owner of a Cessna 170B discovered that the airplane's battery had become discharged over the winter. To start the engine, the pilot attempted to hand-prop the propeller. He reported that he had set the parking brake before beginning the procedure. However, during the starting attempt, the right brake failed. As a result, the airplane began to taxi forward without an occupant on board and struck a hangar.
Damage
The collision with the hangar caused damage to the right wing and flap. Specifically, the outboard two feet of the right wing were bent and wrinkled, and the right flap was pushed into the fuselage.
Aircraft Manual and FAA Guidance
The Cessna 170B maintenance manual notes that a discharged battery should be charged on the ground before a flight is attempted. Additionally, the Federal Aviation Administration’s Flight Training Handbook, AC 61-21A, advises that an engine should never be hand-propped unless a qualified person familiar with all controls is seated at the controls with the brakes set.