Accident Overview
A helicopter conducting a routine early morning rush hour traffic watch experienced a sudden engine failure while at approximately 500 feet above ground level and traveling at about 20 knots. The pilot initiated an autorotation to a nearby parking lot.
Sequence of Events
As the pilot began the autorotation and prepared to land, a car entered the parking lot, its lights becoming visible just before touchdown. With other parked cars occupying portions of the lot, the pilot decided to shorten the approach path and land in an alternate area. After slowing the helicopter to land at this new location, the rotor blades had insufficient inertia to cushion the landing. The helicopter touched down hard, resulting in damage to the undercarriage.
Examination Findings
An examination of the engine revealed that the crankshaft had failed between the number 2 and number 3 cheeks. The engine had accumulated a total operational time of 2,373 hours, with 998 hours of operation since its last overhaul.