On March 28, 2010, about 1215 eastern daylight time, a Robinson R22 Beta helicopter, N72377, operated by Helicopter Academy, ditched in the ocean near Miami Beach, Florida, following a low main rotor RPM event. Visual meteorological conditions prevailed and no flight plan was filed for the Title 14 Code of Federal Regulations Part 91 personal flight. The pilot and passenger were not injured. The helicopter was not located and recovered. The flight originated from the North Perry Airport (HWO), Hollywood, Florida, about 1130. The pilot stated that they were taking photos of boats in an area about 2 miles from the shore of Government Cut. The pilot had just completed a 180 degree turn at about 100 feet above the water when the helicopter’s low main rotor RPM horn sounded. The pilot adjusted the throttle to compensate for the condition. The main rotor speed recovered for about 3 seconds before the condition reoccurred. The pilot entered an autorotation. During the flare, the tail end of the helicopter made contact with the water, causing the helicopter to spin uncontrollably to the right. Both occupants evacuated the helicopter moments before it sank into an area where the ocean floor depths are recorded to be between 150 and 250 feet deep. The passenger’s life vest operated; however, the pilot’s life vest did not inflate at the time, but did when tested later. The helicopter did not have a pyrotechnic signaling device onboard as per the responding Federal Aviation Administration (FAA) inspector, which is required for the type operation that was being conducted. The pilot recalled they were in the water about 10 minutes before a private boat rescued them. The helicopter’s flight manual, performance section, height-velocity diagram was reviewed by the FAA inspector. At the time of the accident, the helicopter was operating at 100 feet above ground level and 40 knots indicated airspeed. Based on the diagram, this combination placed the helicopter within a performance area that the manufacturer recommended avoiding. The pilot holds a commercial pilot certificate with a helicopter rating and a flight instructor certificate for helicopters. He obtained a FAA second-class medical certificate on February 2, 2010. At the time of the accident, the pilot reported he had accumulated 790 hours total flight time. The passenger holds a private pilot certificate with a helicopter rating. He obtained an FAA second-class medical certificate on June 15 2009, with no limitations. At the time of the accident the passenger reported he had accumulated 115 hours total flight time. The helicopter was a two-place, two-bladed single main rotor, single-engine helicopter, with a skid type landing gear. The helicopter was powered by a Lycoming, O-320-B2C, engine rated at 160 horsepower. The responding FAA inspector stated a review of the helicopter’s maintenance records did not reveal any discrepancies with the helicopter prior to the accident flight. The closest official weather observation was at the Miami International Airport (MIA), Miami, Florida, 13.5 miles west of the accident site. The MIA 1153 METAR observed winds from 120 degrees at 13 knots; visibility, 10 statute miles; clouds broken at 1,900 feet above ground level (agl); overcast at 3,300 feet agl; temperature 26 degrees Celsius (C); dew point 21 degrees C; altimeter 30.01 inches of mercury.