SEA BRIGHT, NJ, USA
N900PH
EUROCOPTER AS350D
At 1000 feet mean sea level, the helicopter's engine lost total power. The pilot entered autorotation, and deployed the floats in preparation for a water landing. During the flare, the tailrotor entered the water and separated from the tailboom. An engine teardown revealed that the inner race of the position 19 bearing, which supported the high speed power gearshaft, failed due to fatigue. Subsequently, the #1 and #2 (accessory) gears disengaged. These gears provided drive to the gas generator accessories, which included the fuel pump/control assemblies. With the gears disengaged, there was no drive to the fuel pump, rendering it incapable of delivering fuel to the fuel control.
On May 3, 1995, about 1300 eastern daylight time, a Eurocopter, AS350D, helicopter, N900PH, collided with the water during a forced landing near Sea Bright, New Jersey. The pilot and one passenger were not injured. The helicopter was substantially damaged. Visual meteorological conditions prevailed, and a VFR flight plan had been filed. The on-demand air taxi flight was being conducted under 14 CFR 135. The helicopter had departed the 34th Street Heliport, New York City, New York, at 1245, en route to Keansburg, New Jersey. At an altitude of 1000 feet mean sea level, the helicopter's engine lost total power. The pilot entered autorotation, deployed the floats in preparation for a landing in water, and flared. While in the flare the tailrotor entered the water, and separated from the tailboom. The pilot stated that about 2 miles southwest of Coney Island, New York, the engine chip detector light illuminated. He "pulsed" the light and it went out. About 1 minute later the light illuminated again, but this time would not go out. According to the pilot's written statement: I decided to continue because I was more then halfway across the Raritan [Bay]...about 1 to 2 minutes later the engine lost power, the horn sounded...entered autorotation, made a mayday call, armed [the] floats, popped the floats and completed the autorotation. On May 15, 1995, a preliminary engine teardown was conducted under the supervision of the FAA, at Allied Signal's facilities, Stratford, Connecticut. Additional examinations were conducted at Allied Signal's facilities, Phoenix, Arizona. According to the FAA Inspector's statement, the engine teardown revealed: ...a spur gear assembly had failed and disengaged from [the] opposing gear assembly. The disengagement caused immediate shutdown due to fuel starvation. Further investigation revealed damage to #19 bearing and a worn boss seat area...[when the] gear failure occurred, disconnection of the shaft occurred, and the engine shutdown occurred due to fuel starvation by fuel pump deactivation. Disassembly of the engine revealed that the #1 and #2 accessory gears had disengaged. These two gears provided drive to the Ng (gas generator) accessories, which include the fuel pump/control assemblies. When the gears failed the drive to the fuel pump was lost, rendering it incapable of delivering fuel to the fuel control. The Position 19 bearing, one of two conrad ball bearings, that supports the high speed power take-off gearshaft failed. The gearshaft transmits power from the engine gas producer shaft, at the number two gear mesh, to the high speed accessories located at the accessory gearbox. The bearings are designed to support the combination of radial loads resulting from two spur gear meshes. The Position 19 bearing was damaged, but turned freely. The bearing outer race was fractured axially in a single location and the cage was fractured through four rails on one side and a single rail on the other. Measurements of the bearing diameter clearance showed it to be inconsistent. The gearbox bore, displayed erratic wear. The wear was located in the area of the gear reaction force. The wear allowed a gearshaft center shift of .060"/.070". There were no signs of heating observed. Examination of the Position 19 bearing revealed brinnelling damage on the inner race. Brinnelling dents were visible on both sides of the inner race. Spalling damage was also observed on the inner race. The disassembly revealed that the greatest loss of shaft support, resulted from bearing spinning and wear in the bore. Dynamic loading then caused a fatigue origin in the fillet area, at the ends of the teeth, of the #1 gear (the smaller of the 2 gears). Monmouth Aircraft, the maintenance facility, used by the operator, reported the last chip incident involving this engine was approximately 10 hours prior to the accident. At that time "many fine chips" had bridged the chip detector gap. The chips were not analyzed, because Monmouth had decided to tear down the engine to locate the source of the chips. The teardown revealed, wear on the teeth of the output gear and the mating power idler gear. This was determined as the source of the chips and replaced. At the time of the accident, the pilot had 5,500 total flight hours, and 3,300 flight hours in this make and model helicopter. The reported local weather was; clear, visibility 10 miles, temperature 65 degrees F, dew point missing, wind 225 degrees, 10 knots, altimeter missing.
Failure of the position 19 engine bearing, which resulted in shifting of the accessory gear drive, disengagement of the fuel pump, fuel starvation, and loss of engine power.
Source: NTSB Aviation Accident Database
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