Accident Overview
On June 14, 2012, at 1637 eastern daylight time, a Robinson R22 Mariner, registration N1089N, operated by Watercraft Photo Helicopter LLC, collided with the Atlantic Ocean approximately 10 yards off shore near Oak Island, North Carolina. The helicopter was engaged in a personal flight under 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed, and no flight plan was filed. The flight originated from Wilmington, North Carolina at 1630.
Sequence of Events
The pilot, a private pilot, stated she was in cruise flight at 600 feet mean sea level at 75 knots when she entered an autorotation over the ocean with the intention of performing a power recovery. She lowered the collective pitch to the full down position and rolled the throttle to the full off position. She then raised the collective pitch. The main rotor rpm began to decrease, and a low main rotor audio warning sounded. She rolled on the throttle and increased collective pitch, but the main rotor rpm continued to decrease. The helicopter descended until it impacted the ocean and rolled over inverted.
Passenger Statement
The pilot-rated passenger stated that when the pilot informed him she wanted to perform an autorotation, he replied that he did not feel comfortable because he did not have many hours in the left seat and was unsure if an autorotation could be performed without an instructor pilot on board. When asked if there was anything mechanically wrong with the helicopter before the autorotation, the passenger replied no, stating it was "an improper use of flight controls."
Helicopter Damage
Examination of the helicopter revealed damage to one main rotor blade. The cabin floor, sidewall structure, and center console had separated from the main structure just forward of the forward cabin seats. The bottom of the fuselage was buckled. The left rear skid mount was separated, and the skid assembly was displaced forward. The tailboom assembly was buckled on the lower left side at its attachment point. Evidence of a main rotor blade strike on the tailboom assembly was noted.
Relevant Guidance
The R22 Maneuver Guide, section "STRAIGHT-IN AUTOROTATION WITH POWER RECOVERY," outlines the procedure: Entry from level flight at 70 to 75 kts, 500 to 700 feet AGL, into the wind; smoothly lower collective full down without reducing throttle, coordinate with right pedal and aft cyclic to maintain 75 kt attitude. During the glide, reduce airspeed to 60 to 70 kts. A note indicates that as the aircraft descends through 100 feet AGL, an immediate power recovery should be made if rotor rpm is not in the green, airspeed is not 60 to 70 kts, or rate of descent exceeds 1500 feet. The flare begins at approximately 40 feet AGL with aft cyclic, and power recovery at 8 to 10 feet skid height with forward cyclic.