Incident Overview
A helicopter sustained damage when its main rotor blades impacted a building during ground operations. The pilot reported that he used an electrically powered dolly to back the helicopter out of an aircraft hangar. The dolly's batteries were not charged, so the pilot connected a battery charger with an extension cord to move the helicopter outside.
Pilot Account
The pilot stated that he intended to start the helicopter, warm it up, and check aircraft systems while the dolly batteries charged. Once the batteries were sufficiently charged, he planned to move the helicopter farther from the hangar for takeoff. The pilot had no recollection of the accident beyond sitting in the helicopter with the engine and rotors operating.
Site Examination
Examination of the accident site revealed that the helicopter was facing the hangar, oriented 155 degrees magnetic. The tail of the helicopter was positioned into a very strong wind. The main rotor blades struck the building approximately 6 inches above the door opening and penetrated the structure to a distance of 2 feet, 7 inches.