The non-certificated pilot stated he took off from his home and during the initial climb at 350 feet and 55 mph, the engine quit. At the time there were power lines in front of him so he opted to make a left 90-degree auto rotation. The helicopter was landed hard causing damage to the tail boom of the helicopter. The passenger stated that about 40 seconds after takeoff, he heard a "pop pop" noise. The aircraft started a fast descent and impacted the ground. His injuries include a burst L1 vertebra. Examination of the helicopter was performed by an FAA airworthiness inspector, which revealed the engine was turned by hand without binding. The aircraft's spark plugs were in good condition and the fuel filter was clean and non-obstructed; fuel was noted in the filter. The flight controls were found to be free and moving. No anomalies with the aircraft or engine were reported by the FAA inspector. Inspection of the aircraft's logbooks revealed that the last annual inspection was performed on June 01,1997.