SUNNY ISLES, FL, USA
N83574
Robinson R-22
After about 1 hour of flight at about 200 feet offshore, the helicopter was observed to descend from about 500 feet agl, to about 200 feet agl, and head directly toward the beach. Once overhead the beach, the pilot stated the cylinder head and oil temperature indications started rising rapidly, and he looked for a place to autorotate. Finding no suitable area due to the density of bathers and losing power, the pilot elected to ditch offshore in about 8 feet of water. Post crash test run of the engine revealed normal operation except that the magneto timing had been adjusted as far advanced as possible. Factory post crash analysis of the main rotor clutch and shaft revealed the clutch had sustained two severe overtorque events, most likely as a result of two or more main rotor blade strikes during the accident.
On October 17, 1999, about 1200 eastern daylight time, a Robinson R-22, N83574, registered to a private individual, operating as a Title 14 CFR Part 91 personal flight, crashed into the ocean in the vicinity of Sunny Isles, Florida. Visual meteorological conditions prevailed and no flight plan was filed. The helicopter sustained substantial damage, the commercially-rated pilot received serious injuries, and the ATP-rated passenger received minor injuries. The flight departed Fort Lauderdale, Florida, about 1 hour before the accident. According to the pilot, he was in maneuvering flight about 200 feet above the shoreline when the engine cylinder head and oil temperature gage readings started rising and the engine started losing power. He looked for a clear spot to land on the beach, but could find none, and had to settle for a water ditching in about 8 feet of water, about 50 feet off the shoreline. According to the passenger, who holds airplane/single and multiengine pilot ratings, as well as airframe and powerplant mechanic ratings, the engine started "running funny" just before the loss of power. He characterized his sense as, "..like a car trying to run uphill in fourth gear". He confirmed the rising temperatures as reported by the pilot and added that he noticed the pilot was having to use more throttle to maintain the airspeed they had previously held, and the additional throttle was not getting them any more engine power. He stated that he personally added oil to the 5.5 quart level before departure. According to FAA personnel, the maintenance records were requested of the owner/operator and given the option of personally delivering them or sending them via U.S. Mail, return receipt requested. When the records did not show in reasonable time, the owner was again contacted, and he stated he had sent them, but could not produce a receipt. Maintenance performed and by whom could not be confirmed. Subsequent disassembly examination of the wreckage by FAA and NTSB personnel revealed that the engine crankcase contained about 3.5 quarts of oil and about 4 quarts of sea water. There was no oil slick on the crash site water's surface reported anytime after the accident and the helicopter frame showed no residue or evidence of oil release from the crankcase. The transmission fluid was missing and had been displaced with sea water. Both magnetos were found timed to a position as far advanced as their adjustment slots would allow, (40 degrees BTDC vs the recommended 25 degrees BTDC). Both transmission drive belts were found displaced rearward on the engine driven pulley, but still engaged. The rotor drive free-wheeling unit, or sprag clutch, was found to allow the rotor drive train to rotate freely in either direction. The clutch assembly was sent to the factory for failure analysis. The engine was removed from the chassis and run in a test cell for about 25 minutes at power settings the passenger stated were being used just before the loss of power that preceded the accident. The engine started instantly and ran smoothly. The magneto check showed no decay of rpm when switching from both to either left or right, and was attributable to the extremely advanced magneto timing adjustment. The oil screen was inspected prerun and postrun, and revealed only sand and dirt, but no metal. The compression was checked for all cylinders and showed: (1) 72/80 lbs., (2) 74/80 lbs., (3) 74/80 lbs., (4) 74/80 lbs. The oil pressure held at a steady 65 lbs. and oil temperature held at a steady 210 degrees, (F). The cylinder head temperatures ranged from 350 to 375 degrees, (F) for the four cylinders. Disassembly examination of the sprag clutch assembly by Robinson factory personnel, with NTSB oversight, revealed that the clutch had received at least two severe overtorque events which resulted in the sprag cams rolling over. The clutch shaft revealed severe indentations, proof that the clutch cams were properly locked and driven when they received the overtorque events, most likely caused by two or more main rotor blade strikes during the accident. The indentations were spaced and shaped corresponding to a normal clutch contact pattern. The inner clutch cage was fractured in two different locations. The sprag contact surface on the shaft had been worn and showed roughness and discoloration greater than normally seen in parts after 2,000 hours of service, the normal overhaul cycle.
A loss of engine power while maneuvering due to improper ignition timing by unknown person(s) resulting in an emergency descent and collision with the water.
Source: NTSB Aviation Accident Database
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