Robinson Helicopter Company R22 MARINER N1089N accident near Oak Island, North Carolina

Probable cause

The pilot's failure to properly execute the helicopter practice autorotation recovery, which resulted in a collision with the water.

NTSB analysis

According to the pilot, the helicopter was established in cruise flight at 600 feet mean sea level and an airspeed of 75 knots when she entered a practice autorotation over the ocean, with the intention of a power recovery. The pilot lowered the collective pitch to the full down position and rolled the throttle to the full off position. The pilot then raised the collective pitch and the main rotor rpm started to decrease and the low main rotor audio sounded. The pilot increased the throttle and increased collective, and the main rotor rpm continued to decrease. The helicopter continued to descend until it impacted the ocean and rolled over inverted. The pilot and pilot-rated passenger stated there were no mechanical problems with the helicopter.

Text from the NTSB. Open the NTSB docket for ERA12LA399 for the full record.