What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
(-23) At cruise power 21 inches mp, approx 450 feet +/- 50 ft at 70 mph heading north, over mosquito lagoon the pilot all of a sudden noticed that the aircraft was unusually quiet and rotor RPM was decreasing. He added throttle and lowered collective however the engine did not respond. He immediately entered an autorotation landing in mosquito lagoon, the helicopter hit the water nose high with little or no forward airspeed, and then settled in the water level, rolled left and sank immediately. The helicopter came to rest in 5 ft of water about 150 feet due west of the boat dock at privacy data omitted pilot stated that obstructions on shore (houses, dense vegetation, boat docks with railings) did not allow for an autorotation to shore. Helicopter received substantial damage to main and tail rotor blades and tail boom.
As the FAA filed it
(-23) AT CRUISE POWER 21 INCHES MP, APPROX 450 FEET +/- 50 FT AT 70 MPH HEADING NORTH, OVER MOSQUITO LAGOON THE PILOT ALL OF A SUDDEN NOTICED THAT THE AIRCRAFT WAS UNUSUALLY QUIET AND ROTOR RPM WAS DECREASING. HE ADDED THROTTLE AND LOWERED COLLECTIVE HOWEVER THE ENGINE DID NOT RESPOND. HE IMMEDIATELY ENTERED AN AUTOROTATION LANDING IN MOSQUITO LAGOON, THE HELICOPTER HIT THE WATER NOSE HIGH WITH LITTLE OR NO FORWARD AIRSPEED, AND THEN SETTLED IN THE WATER LEVEL, ROLLED LEFT AND SANK IMMEDIATELY. THE HELICOPTER CAME TO REST IN 5 FT OF WATER ABOUT 150 FEET DUE WEST OF THE BOAT DOCK AT ^PRIVACY DATA OMITTED^ PILOT STATED THAT OBSTRUCTIONS ON SHORE (HOUSES, DENSE VEGETATION, BOAT DOCKS WITH RAILINGS) DID NOT ALLOW FOR AN AUTOROTATION TO SHORE. HELICOPTER RECEIVED SUBSTANTIAL DAMAGE TO MAIN AND TAIL ROTOR BLADES AND TAIL BOOM.
NTSB investigation
The NTSB’s investigation of this event, with its probable cause and findings. Matched to this report by N-number and date.