HANA, HI, USA
N9205F
HUGHES 369HS
DURING DEPARTURE, UPON REACHING 100 FEET ALTITUDE AND 60 KNOTS AIRSPEED, THE PILOT EXPERIENCED AN AIRFRAME VIBRATION ACCOMPANIED BY A FUEL FILTER CAUTION LIGHT, ENGINE POWER WARNING LIGHT AND HORN, AND LOSS OF ENGINE POWER. IN THE ENSUING AUTOROTATION, A HARD LANDING RESULTED IN THE MAIN ROTOR SEVERING THE TAIL BOOM. SUBSEQUENT INVESTIGATION REVEALED THAT THERE WAS A LEAK IN THE FUEL FILTER BYPASS SWITCH WHICH PERMITTED AIR TO ENTER THE SUCTION-FED ENGINE FUEL SYSTEM. INSPECTION OF THE SWITCH DISCLOSED LEAKAGE BETWEEN THE MATING FLANGE HALVES DUE TO DETERIORATED SAFETY WIRING. THE LAST SCHEDULED MAINTENANCE ON THE AIRCRAFT WAS PERFORMED 77 HOURS PRIOR TO THE ACCIDENT.
On October 11, 1995, at 1755 hours Hawaiian standard time, a Hughes 369HS, N9205F, was substantially damaged during an emergency landing shortly after takeoff from Hana Airport on the island of Maui, Hawaii. The commercial pilot was not injured, however, his four passengers received minor injuries. The aircraft was being operated as a sightseeing flight by AlexAir under 14 CFR Part 135 when the accident occurred. Visual meteorological conditions prevailed and a company VFR flight plan was filed. The pilot reported departing from runway 8/26 at midfield. Upon reaching 100 feet altitude at 60 knots, he experienced a lateral vibration he thought was due to rotor imbalance. He had lowered the collective control and slowed for a normal descent when he noted that the fuel filter light had come on. This was followed immediately by the engine failure light and warning horn, and a loss of engine power. The pilot said he then initiated an autorotation back to the runway. He "lowered collective and nosed the helicopter forward to try to get some airspeed for a flare at about 30 feet," however, he was unable to flare and level the helicopter before the tail boom and landing skids impacted at the same time on the runway. The main rotor blades then flexed downward and severed the tailboom. Subsequent examination of the aircraft by inspectors from the FAA's Honolulu Flight Standards District Office revealed that there was a leak in the fuel filter bypass switch which allowed air to enter the suction-fed engine fuel system. The fuel filter bypass switch was manufactured by the R. W. Jenson Company as part number 800175-3 (McDonnell Douglas Helicopter/Hughes P/N 369H8144) circa 1974. The last 100-hour inspection of the aircraft was performed 77 hours prior to the accident. Following the accident the switch was inspected and tested at Spectra-Lux Corporation, who currently manufacture the switch under license. The inspection revealed leakage between the mating flange halves. The leakage was due to deteriorated safety wiring which permitted the machine screws holding the flanges together to loosen. When the screws were tightened, the leakage stopped and the switch functioned to the manufacturers' specifications.
the loss of engine power due to inadequate maintenance inspection of the fuel system which permitted air to enter the engine fuel supply. A factor in the accident was the pilot's improper execution of the autorotation landing.
Source: NTSB Aviation Accident Database
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