Robinson Helicopter R22 BETA N456SH accident near Winter Haven, Florida

Probable cause

A loss of engine power for undetermined reasons.

NTSB analysis

The pilot stated that during the downwind leg for a practice autorotative landing while flying at 600 to 625 feet mean sea level with the governor on, he applied carburetor heat and five seconds later he perceived by sound that the engine lost power. He turned onto base leg, and attempted to restart the engine but allowed the main rotor rpm to decrease to 87 percent. He stopped his restart attempts and initiated descent for an autorotative landing. He maintained 65 knots during the descent and when the flight was at 40 feet with obstacles ahead (mobile homes), he intentionally slowed the helicopter. At 20 feet above ground level he pulled collective which activated the main rotor rpm warning and resulted in a hard landing. Postaccident examination of the helicopter revealed the throttle, mixture, and carburetor heat control rigging were correct. No contaminants of the fuel system were noted. Following recovery of the helicopter with the main rotor blades removed, an FAA inspector observed the engine start and operate to idle rpm. The conditions (temperature and dew point) were favorable for serious carburetor icing at only glide power.

Text from the NTSB. Open the NTSB docket for ERA09LA284 for the full record.