Mattituck, NY, USA
N9244F
Hughes 369HS
While aggressively maneuvering over the shore and ocean, below 100 feet above ground level, the helicopter experienced a total loss of engine power. The pilot entered an autorotation, and activated the float system. The helicopter impacted the water in a level attitude, but with enough forward speed to become submerged and then bounce 15 to 18 feet back into the air. The helicopter impacted the water a second time, but this time inverted. Both occupants egressed the submerged helicopter, and were rescued shortly after reaching the surface. A postaccident examination of the helicopter revealed main rotor blade damage consistent with a loss of power; however examination of the engine and powertrain were inconclusive.
On May 28, 2006, at 1518 eastern daylight time, a Hughes 369HS, N9244F, was substantially damaged near Mattituck, New York, after it impacted water during a forced landing. The certificated private pilot and the passenger received minor injuries. Visual meteorological conditions prevailed, and no flight plan was filed for the flight that departed from a field near Mattituck, about 1510. The personal flight was conducted under 14 CFR Part 91. According to the pilot he had approximately 40 gallons of fuel onboard. He had "just departed" from private property and was climbing to approximately 600 feet mean sea level (msl). He then began to turn right to a "southeasterly" heading when he "heard and felt" a bang. He noted that the red engine out light began to flash, the engine speed began to decrease, and he could hear the auto relight "clicking." The pilot leveled off the helicopter and adjusted the flight controls for autorotation. At approximately 20 feet msl, he started to flare and activated the float system. He then leveled off the helicopter once again and "pulled collective" to stop the descent rate. The helicopter touched down on the waters of Long Island Sound in a "relatively" level attitude with a "slight" forward movement, nosed over, and became inverted. According to the passenger, the pilot flew the passenger's father and brother on a "short ride" prior to the accident flight. On the accident flight, the passenger and the pilot "flew to the ocean, and waved at fishermen." As they started to "return to the vineyard," the engine "got quiet," they "tilted down," and then "went underwater." He believed that the pilot inflated the pontoons when they hit the water. After the helicopter struck the water, it took the passenger about 15 seconds to find his seatbelt and egress. Approximately 1 minute after ascending to the surface of the water, they were picked up by a fishing boat. According to a witness who was standing on the beach, the helicopter first appeared from behind him, passing over the top of a "bluff" from the west. The helicopter appeared to be "about 25 to 30 feet above the treeline" when it passed overhead. It then turned "hard left" into an approximate 90-degree bank and descended toward the beach. The helicopter then paralleled the beach in a westerly direction and then turned to the right (north) and proceeded out over the water for about a mile. It was then observed by the witness to reverse, and head in a southerly direction, back towards land at "high speed" approximately 50 feet above the water. When the helicopter reached the shoreline it banked to the left and flew towards the witness at 15 to 20 feet above the shoreline. Shortly before passing over the witness it climbed, slowed, and then headed back over the bluff. The helicopter reappeared over the top of the bluff, 5 to 10 minutes later. It was flying about 25 to 50 feet above the treeline. The witness then observed sand blowing on the ground because of the low altitude of the helicopter. The helicopter then "banked hard 90-degrees to the left," and paralleled the shoreline about 30 feet offshore at approximately 50 feet above the water, traveling in a westerly direction. The witness next observed the helicopter bank "very hard right" and proceed out over the water for approximately a quarter of a mile. The helicopter once again "banked hard right, this time exceeding 90 degrees," and the witness heard the "motor revving very high." As the helicopter approached the shore, it "banked left," again "past the 90-degree mark," and engine noise increased. The helicopter returned to level flight, but the "engine did not sound well." The witness then heard a "bang," and the helicopter began to lose speed and altitude "fast." Gray smoke began to emanate from the back of the helicopter, and the floats inflated. The helicopter struck the water "flat down," and the rotor blades severed the tail boom, as the helicopter became submerged. The helicopter then "popped" out of the water and into the air, reaching approximately 15 to 18 feet. It then impacted the water again, but this time inverted, and sank. PERSONNEL INFORMATION According to the pilot and Federal Aviation Administration (FAA) records, the pilot held a private pilot certificate with a rating for rotorcraft helicopter. He reported 1,800 total hours of flight experience, 1,700 hours of which were in helicopters, and 1,400 hours of which were in make and model. His most recent third-class medical certificate was issued on March 9, 2004, and had expired two months prior to the accident. AIRCRAFT INFORMATION According to FAA and maintenance records, the helicopter was manufactured in 1975. It had accrued 7,290.5 total hours of operation. It's most recent annual inspection was completed on July 27, 2005. METEOROLOGICAL INFORMATION A weather observation taken about 25 minutes prior to the accident, at Francis S. Gabreski Airport (FOK), Westhampton Beach, New York, located approximately 12 nautical miles southwest of the accident site, recorded the wind as 140 degrees at 9 knots, visibility 10 miles, clear skies, temperature 73 degrees Fahrenheit, dew point 57 degrees Fahrenheit, and an altimeter setting of 30.15 inches of mercury. WRECKAGE AND IMPACT INFORMATION Examination of the airframe and powerplant was conducted under the supervision of the FAA. During the examinations no preimpact mechanical malfunctions were discovered. Airframe and Drive System Examination Examination of the forward portion of the fuselage revealed that portions of the chin bubbles were missing and the lower left forward fuselage exhibited compression damage. The rear section of the fuselage including the aft fairing and the remaining forward portion of the tailboom exhibited crushing and tearing, consistent with a main rotor blade strike, and was displaced to the right. The aft section of the tailboom, tail rotor assembly, and vertical fin, were missing. Examination of the remains of the forward portion of the tail rotor driveshaft revealed evidence of rotational scoring and torsional overload with the torsion in the drive direction. The main rotor blades exhibited varying degrees of damage. The Blue blade exhibited a 90-degree bend just outboard of the blade grip, chordal separation outboard of station 93 and trailing edge separation between the upper and lower surfaces. Red and white paint transfer marks were also discovered along the leading edge abrasion strip. The Green blade exhibited bending just outboard of the blade grip with portions exhibiting separation of the trailing edge. The Yellow blade exhibited bending, downward bowing and trailing edge separation. The Red blade exhibited no damage. Engine Examination External examination of the engine revealed that water was present throughout the engine with multiple areas exhibiting corrosion consistent with immersion in seawater. The engine-to-transmission driveshaft was intact and coupled. No evidence of compromised engine inlet structure was discovered. Examination of the engine bay and upper deck did not reveal any evidence of oil or fuel leaks. Inspection of the compressor inlet and inlet plenum did not reveal any evidence of foreign material and/or damage. No anomalies were noted with either the combustion or turbine sections. Attempts to rotate the gas producer turbine (N1) shafting from the compressor rotor and the N1 tachometer drive were unsuccessful. The starter/generator drive gear was turned with a spline wrench. The gear turned freely and did not feel as if there was continuity. The power turbine (N2) shafting system was free and continuous from the N2 rotor to the accessory gearbox. The drive train was continuous from the main rotor head to the power take-off gear. Torque applied to the engine-to-transmission driveshaft, resulted in an approximate 3-degree rotation of the rotor head and power take-off gear. The freewheeling unit functioned in both the drive and coast directions. The fuel control throttle lever was observed to be in the full open position. A rigging check was conducted with full stop-to-stop contact at the fuel control unit as actuated from the twist grip. Full stop-to-stop travel was achieved with the idle detent corresponding to 30 degrees. The collective was in a full down position when first observed. The linkage was continuous to the power turbine governor throttle lever. A collective pitch rigging check was conducted with collective down indicating 60 degrees; collective up indicating 80 degrees governor. Internal examination of the engine revealed that, the gas producer turbine (N1) was bound. The N1 rotor turned freely once the turbine was removed from the accessory gearbox. The N2 was bound in the assembled condition but the N2 was free to turn after the turbine module was removed. The N2 drivetrain, in the accessory gearbox remained bound. N1 and N2 shafting were found intact with no apparent damage. The N2 gear, and fuel control unit drive shafts turned freely. All bearings were functional and intact and all of the oil standpipes were clear. No damage to the compressor's axial and centrifugal components was evident and two small pieces of a fiberglass substance were found in the aft stages of the compressor case halves. The spur adapter gearshaft was in good condition. The compressor case halves were void of damage and the compressor impeller was undamaged. TESTS AND RESEARCH Examination and testing of the helicopter's fuel system was conducted in the United States under the supervision of the FAA. Examination and testing of the fuel control and power turbine governor, engine driven fuel pump and the fuel nozzle were conducted in the United Kingdom with oversight provided by the Air Accidents Investigation Branch. Examination and testing of the aircraft fuel system revealed no anomalies. A vacuum kit was connected to the upper drain plug of the engine driven fuel pump filter bowl and 8 inches of Hg was applied. No loss was observed during the test. Approximately 40 cc of clean fuel was drained from the fuel pump filter bowl. The 5u engine driven fuel pump filter was clean. Residual fuel was drained from the Pn line between the in-line check valve and the fuel nozzle. The fuel control and power turbine governor were subjected to testing in accordance with published service limits. Both units were functional with only minor deviations observed. The fuel pump was disassembled and found in good condition with no evidence of mechanical failure. The fuel nozzle was heavily corroded at the air shroud with corrosive buildup in the area of the primary and secondary orifice; however, the inlet screen and metering set were free of contaminants.
A loss of engine power due to undetermined reasons.
Source: NTSB Aviation Accident Database
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