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On May 30, 2002, about 1720 mountain daylight time, a restricted category Sikorsky CH-19E, N94475, sustained substantial damage after a loss of engine power and forced landing while conducting external load operations near Plains, Montana. The helicopter is registered to Tri Corp of Clarkston, Washington, and was being operated under the provisions of Title 14, CFR Part 133. The commercial pilot, the sole occupant, received minor injuries. Visual meteorological conditions prevailed and no flight plan was filed for the local flight. The flight originated from an off-airport service landing area approximately 10 minutes prior to the accident.
In a written report, dated June 08, 2002, the pilot stated that he was flying sideways downhill with an external load on a long line. He approached the log landing area in a turn and attempted to set the load down, however the helicopter, "seemed to keep going." The helicopter began to lose altitude. To compensate, the pilot lowered the collective, and increased the throttle. The aircraft did not respond to the pilot's actions. However, a subsequent maneuver to avoid colliding with a loader was successful. The pilot stated that he remembered, "putting the ship down easy." The pilot then related that the helicopter suddenly "lifted over to the left and next I was undoing my seatbelt and climbing out of the pilot window." The pilot also noted that on a previous flight the helicopter seemed to lack power.
A witness to the accident reported that she could see "the helicopter steadily lose altitude from a few hundred feet in the air." She then related that she heard the engine quit, followed by the sound of impact a few seconds later.
At the time of the accident, the pilot held a second-class medical certificate dated April 2, 2002. The medical certificate carried no limitations or waivers. Among other certificates and ratings, the pilot holds a commercial pilot certificate with a helicopter rating dated October 20, 2000.
According to the Pilot/Operator Report (NTSB form 6120.1/2) submitted by the pilot, his total time in all aircraft is 1,327 hours. The pilot has accumulated approximately 444 hours pilot-in-command, of which 42 were accrued in the accident aircraft make and model.
The accident helicopter, a Sikorsky CH-19E, serial number 130141, was originally manufactured on June 21, 1952. Maintenance records indicated that the airframes last inspection, an annual inspection, was completed on January 31, 2002. At the time of the inspection the airframe had accumulated approximately 5,537 hours total time. The engines last inspection, and annual inspection, was completed on January 31, 2002. Maintenance records indicated that the engine total time was 5,537; 681 hours since major overhaul (TSMO).
WRECKAGE AND IMPACT INFORMATION
The helicopter was observed by FAA inspectors to have come to rest on its left side. The engine, transmission, mast and rotor assembly remained intact. The main rotor blades displayed upward bending and extensive deformation. The tail rotor drive shaft was separated just forward of the tail boom, however, the entire assembly was accounted for. The tail boom assembly was partially separated and bent to the left of the fuselage. The tail rotor assembly was intact and both tail rotor blades were attached to the gearbox. Tip and leading edge damage was noted to the blades. The vertical stabilizer was partially separated and had rotated approximately 90 degrees. The horizontal stabilizer was intact and showed little damage.
The accident occurred during the hours of daylight at 47 degrees 28 minutes north, 114 degrees 59 minutes west.
On June 25, 2002, a FAA maintenance inspector from the Boise, Idaho, Flight Standards District Office, examined the wreckage and conducted an engine test run. The inspector reported that the fuel system was intact and the vents were unobstructed. He reported that a small amount of metal shavings were present in the fuel tank sump and main fuel sump, however, the fuel filter screen was clear. The magnetos switch was checked utilizing an Ohmmeter and determined to be functional. At the conclusion of the examination the helicopter engine was started. The inspector reported that the engine ran for approximately five minutes without incident.
On July 19, 2002, representatives from the NTSB and Precision Aviation Products Corporation examined the carburetor at Precision's facility in Everett, Washington. Flow bench testing and disassembly revealed no abnormalities with the carburetor (report attached).
At the conclusion of the investigation, the aircraft wreckage was released to Tri-Corp, Clarkston, Washington.