Aspen, CO, USA
N214B
Bell 214B-1
According to the pilot, as he brought the helicopter to a 90-foot hover, he felt a "slight shudder" as the engine experienced a compressor stall. He stated that the engine rpm dropped to idle and he noticed the fuel flow had dropped to "idle fuel flow." He turned the helicopter downhill and attempted a forced landing on a nearby ski slope. The helicopter struck the ground with its nose, slid approximately 30 feet, and rolled over on its left side. The impact crushed the forward section of the fuselage, buckled the tail boom, and separated the vertical fin, tail rotor assembly, and both landing gear skids. The engine continued to run at idle after the helicopter came to rest. During a serviceability inspection of the engine's wire harness, a broken wire was located in the overspeed control unit's cannon plug. The wire in the "crimp type" cannon plug had been repaired with a solder joint, which is not allowed due to the close tolerance of the pins. According to the technician, the broken wire condition, in itself, would not engage the overspeed system or result in the loss of engine power. However, it was noted that, due to the close tolerance of the pins, any movement of the broken wire could enable the solder joint on one pin to touch the other pin. During a bench test, the technician stated that he "shorted pin B to pin C." This shorted condition resulted in the inadvertent activation of the fuel shut-off valve, which would result in the reduction of engine power to approximately 50 percent.
On September 17, 2004, at approximately 1300 mountain daylight time, a Bell 214B-1, N214B, operated by Central Copters, Inc., was substantially damaged during a forced landing following a loss of engine power near Aspen, Colorado. Visual meteorological conditions prevailed at the time of the accident. The local flight was being conducted under the provisions of Title 14 CFR Part 91 without a flight plan. The commercial certificated pilot was not injured. The flight was originating at the time of the accident. According to the pilot, he was departing a staging area on the side of a ski slope. As he brought the helicopter to a hover at approximately 90 feet agl, he felt a "slight shudder" as the engine experienced a compressor stall. He stated that the engine rpm dropped to idle and he noticed the fuel flow had dropped to "idle fuel flow." He turned the helicopter downhill and attempted a forced landing on a nearby ski slope. The helicopter struck the ground with its nose, slid approximately 30 feet, and rolled over on its left side. The impact crushed the forward section of the fuselage, buckled the tail boom, and separated the vertical fin, tail rotor assembly, and both landing gear skids. The engine continued to run at idle after the helicopter came to rest. On November 3, 2004, the engine was examined and functionally tested. No pre-impact conditions were found that would have interfered with normal engine operation. The engine performed normally throughout the functional test and the test could not duplicate the loss of power condition as described by the pilot. On April 26, 2005, a maintenance technician completed a serviceability inspection of the engine's wire harness assembly. The wire harness assembly, which connects the airframe to various engine components, was in "very poor condition with bare wires showing, plugs in deteriorated condition [and] with o-rings missing." The harness was not in a "serviceable condition." During the inspection, he identified a broken cannon plug wire. The broken wire was identified as the lead wire for pin B in the engine's overspeed trip system cannon plug. Upon further inspection, he noted that, on the same cannon plug, the lead wire for pin A broke free with very little effort. The two cannon plug wires were identified as the primary power and ground wires for the engine's overspeed control unit. An examination of the cannon plug revealed that the wire had been repaired with a solder joint. The original insulation between the sockets had been removed and the solder joints were covered with heat shrink tubing. The cannon plug (1P32, p/n PT06CP-8-4S) is a "crimp type" cannon plug, which requires crimp pins. Soldering is not allowed due to the close tolerance of the pins. A bench test was conducted on the wire harness, in which power was applied and then removed. The technician stated that "no false triggers of the fuel [shut-off] valve" were noted. According to the technician, the broken wire condition, in itself, would not engage the overspeed system or result in the loss of engine power. However, it was noted that the broken cannon plug wire was next to the lead wire for pin C, which is connected directly to the engine's overspeed fuel shut-off valve. Movement of the broken wire could enable the solder joint on pin B to touch pin C, which could inadvertently activate the fuel shut-off valve. During a second bench test, the technician stated that he "shorted pin B to pin C." This shorted condition resulted in the inadvertent activation of the fuel shut-off valve, which resulted in the reduction of engine power to approximately 50 percent. No further system or airframe anomalies were noted.
the inadvertent activation of the engine's fuel shut off valve, resulting in the reduction of engine power to 50 percent due to an improper cannon plug wire repair on the engine's wire harness assembly. Contributing factors include the improper wire repair, the low altitude, and the lack of suitable terrain for a forced landing.
Source: NTSB Aviation Accident Database
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