Incident Overview
During cruise flight at 800 feet MSL, the pilot heard a whine that was slightly different from the normal engine whine. Subsequently, a loud snap or bang was heard, accompanied by severe vibrations. The pilot determined a dual engine failure had occurred. The number one engine fire warning light then illuminated, and the smell of smoke was noticed.
Emergency Response
The pilot initiated an autorotation to a mall parking lot. During the descent, the pilot increased collective to clear trees bordering the parking lot. The helicopter touched down and slid approximately 200 feet before coming to a stop. When a nurse opened the door to evacuate, smoke billowed into the cabin from the tunnel area. After confirming that the flight crew was well clear, the pilot exited the helicopter.
Post-Accident Examination
Examination of the helicopter revealed that the drive shaft for the left engine had separated from the transmission input shaft flange. Further examination of the main transmission lower housing showed debris partially blocking the oil channel for the left side input pinion. Both engines exhibited internal thermal and foreign object damage.