SEA01MA163

The Kawasaki Vertol KV-107 II rotorcraft had departed the helibase on a non-mandatory test flight requested by the pilot-in-command (PIC) to 'tweak' the rotorcraft's engine synchronization system. The test flight was conducted with the bucket and 150 foot long line attached to facilitate the test procedure. Witnesses reported observing the rotorcraft between 300 and 1,000 feet in altitude and beginning a climb when it began to pitch/roll and descend rapidly. Several witnesses reported seeing the bucket horizontal to the rotorcraft and also caught up in one of the rotors. The aircraft impacted on its right side intact with the exception of its rotor blades. Two of the three forward rotor blades were found 600-900 feet from the ground impact site. The third forward rotor blade, which was broken in half, was found with its outboard section at the ground impact site and the inboard half approximately 100 feet away. All three aft rotor blades were found in close proximity to one another and approximately 400 feet distant from the primary ground impact site. All six blades separated from their root sections in about the same place and a post crash fire destroyed much of the rotorcraft. Post crash examination established control continuity from the cockpit area through the control closet and on to all the associated hydraulic actuators as well as the continuity of the entire synchronization drive shafting. Examination and disassembly of all major components revealed no evidence of any fatigue propagation, disconnects, or characteristics of other time dependent failure mechanisms. All hydraulic actuators underwent an X-ray examination and disassembly and there was no evidence of any blockage or jamming within any of the actuators. The engines were examined and disassembled and the gas generator speed range for both was determined to be between 64.3% and 69.7%, or about 10% above ground idle. There was evidence that the long line cable encountered/impacted the nose gear strut, as well as an aft strut, the forward left side of the fuselage, the forward rotor head rain shield and all three forward rotor blades. It could not be determined whether the cable to rotor interaction was an initiating event or the result of a previous occurrence which allowed the cable to become entangled with the forward rotor blades. The PIC had more than 1630 hours of V-107 rotorcraft time of which more than 670 hours were logged as PIC time. The co-pilot had more than 150 hours of V-107 rotorcraft time none of which was PIC time.

History of flight

On August 31, 2001, approximately 0905 hours mountain daylight time, a Kawasaki KV-107 II rotorcraft, N186CH, registered to and operated by Columbia Helicopters Leasing, Inc., and being flown by two commercial pilots, was destroyed when it collided with terrain following a loss of control in flight during a cruise/climb phase of operation. The crash site was approximately three miles south of Emigrant, Montana. Both pilots and the onboard mechanic were fatally injured. A post-crash fire destroyed much of the rotorcraft. Visual meteorological conditions existed and no flight plan had been filed. The flight, which was a non-mandatory maintenance check flight following a phase five inspection, was to have been operated under 14CFR91, and originated from the Fridley Helibase staging site approximately eight nautical miles north of the crash site and slightly north of Emigrant, Montana. The rotorcraft was estimated to have departed on the check flight approximately 0845. The aircraft was under contract with US Forest Service and was engaged in firefighting operations in support of the Fridley Fire centered approximately eight nautical miles north and west of Emigrant, Montana.

The rotorcraft departed the Fridley helibase approximately 0845 hours with both pilots and a mechanic aboard. At this time the rotorcraft had been released from the United States Forest Service (USFS) contract and would remain so for the duration of the test flight (refer to Attachment USDA-I). Immediately prior to departure the ground crewman observed the copilot occupying the right seat within the cockpit (refer to Attachment EK-I).

Witness data

There were seven witnesses located circumferentially around the accident site who observed the rotorcraft immediately prior to or during the crash sequence. The witnesses were located throughout all four quadrants of the compass (N/S/E/W) at distances ranging from less than one-half a mile up to three miles from the crash site (refer to Chart I which shows the approximate location of all seven witnesses).

A synopsis of key observations from each of the witness's statements follows (refer to attached individual witness statements one through seven for additional details):

Witness #1, who was located approximately one-half mile south of the accident site, and was looking north at the rotorcraft, reported that he saw it "dropping," facing south while rotating very slowly to the left; and that the rotorcraft was starting to drop to the left side. The witness believed that the tether and bucket were still below the rotorcraft at the time he observed it and that the rotorcraft was approximately 300 feet above the ridge when he first saw it dropping.

Witness #2, who was located approximately one mile south of the accident site, and was looking north at the rotorcraft, reported that he saw something "spinning" and "dropping fast out of sight."

Witness #3, who was located approximately one and one-half miles east of the accident site, and was looking west at the rotorcraft, reported that he saw it "wobbling" and then it "started down spinning."

Witness #4, who was located approximately three miles north of the accident site, and was looking south at the rotorcraft, reported that he saw "a chopper with [the] water bucket flying erratically." He commented that it seemed that the rotors "were not functioning properly" and that the rotorcraft was "going down fast in a circular pattern." He also reported the rotorcraft as rolling from side to side about 1,000 feet above ground.

Witness #5, who was located approximately two miles northwest of the accident site, and was looking southeast at the rotorcraft, reported that he had a side view of a light colored helicopter, which was "flying northbound" and "pulling a water bucket" and that "all looked fine." He reported further that after about five to six seconds of observation he witnessed the "aft (back) drop down and the forward (front) end rise up and go completely upside down." Additionally, he reported that as the aircraft approached a fully inverted attitude nearly horizontal with the ground he witnessed "the aft rotor blade catch the water bucket's cable and sling it around and round wildly." He then observed the rotorcraft descend inverted in a "left to right turn" with the bucket and cable entangled.

Witness #6, who was located approximately two miles west northwest of the accident site, reported that she observed the helicopter fly over highway 80 towards the Yellowstone River with the "basket hanging below and slightly behind [the] helicopter as it flew." After crossing over the Yellowstone River the helicopter appeared to climb and turn northward roughly paralleling the river. She reported that as the helicopter made this left turn "it seemed to suddenly start a sharp descent," "the nose seemed to dip lower" and "the left hand turn became sharper." The helicopter was observed to "lean steeply to the left" and the basket remained attached by its line and "became parallel to the helicopter as it continued its descent." She reported that the helicopter then turned back to the right and seemed to descend in a clockwise rotation at which point the "rotors appeared to have stopped rotation." The helicopter turned back to the left and rolled slightly on its side at which time "the basket was almost above the helicopter." She observed the helicopter then turn back to the right and level out slightly, during which "there was no rotation of the blades." The helicopter made one last turn to the left before descending from view.

Witness #7, who was located approximately one mile south southwest of the accident site, and was looking generally north at the rotorcraft, reported seeing the helicopter fly over and then turn north while carrying a water bucket. She reported that about one mile north of her location she observed the helicopter "pause and then descend with great speed," and that while it was descending she observed "one of the propellers and other parts from the top area of the helicopter fly off as it was descending."

Personnel information

Pilot-in-command:

The pilot-in-command (PIC), who according to the operator would have been assigned the left cockpit seat, held a commercial pilot certificate with helicopter and instrument (helicopter) ratings as well as a type rating in the BV-107 (VFR only limitation). According to the operator, he had accrued approximately 3,889 hours of flight experience, all logged in rotorcraft, and approximately 1,715 hours were logged as PIC time. Additionally, he was reported to have logged approximately 1,631 hours in the Vertol V-107 model rotorcraft of which approximately 671 hours were as PIC. He had been issued a second class medical with no waivers/limitations on September 14, 2000.

Co-pilot:

The co-pilot, who according to the operator would have been assigned the right cockpit seat, held a commercial pilot certificate with helicopter and instrument (helicopter) ratings and private pilot ratings in both airplane single engine land and instrument (airplane). He was not type rated in the BV-107 rotorcraft. He also held a certified flight instructor certificate with ratings in both helicopter and instrument (helicopter). According to the operator, he had accrued a total of approximately 1,354 hours of flight experience of which approximately 1,076 hours were as PIC and approximately 1,298 hours were logged in rotorcraft. Additionally, he was reported to have logged approximately 154 hours in the Vertol V-107 model rotorcraft, none of which was logged as PIC time. He had been issued a first class medical with no waivers/limitations on January 4, 2001.

Crewman:

The crewman, whose location in the rotorcraft could not be determined, held an FAA airframe and powerplant mechanic certificate. According to the operator, he had been engaged in maintenance on the r