NTSB Factual Report

On February 7, 2001, approximately 1400 mountain standard time, a Western International UH-1H restricted-category former surplus military helicopter, N205GL, registered to and operated by Grim Logging Company, Inc. of Salem, Oregon, experienced an inflight loss of control and subsequent collision with terrain while performing a 14 CFR 133 rotorcraft external-load logging operation near Darby, Montana. The helicopter was substantially damaged and the helicopter's sole occupant, the airline transport pilot-in-command, was fatally injured in the accident. Visual meteorological conditions prevailed and no flight plan had been filed for the local flight, which originated near Darby about 1345.

A report from the operator stated that the pilot was on the last half of his first external load of the afternoon when he reported over the radio, " tail rotor failure, look out landing" (referring to the log landing crew.) The operator's report stated that the pilot released his logs from the lower hook, but retained his 150-foot line, and that he flew over the log landing to regain airspeed, with the helicopter's rotation angle never exceeding 90 degrees from its flight path. The operator's report stated that the helicopter's long line then snagged a tree on the far side of the landing, causing the aircraft to roll left and pitch nose down. The aircraft impacted the ground 250 feet from the snagged tree, nose low, with between 100 and 130 degrees of left roll (according to the operator's report), landing on the top left crew door post. The pilot was flying from the left pilot seat with his shoulder harness unfastened, according to the operator's report.

An FAA inspector from the Helena, Montana, Flight Standards District Office (FSDO) responded to the accident scene and performed an on-site examination of the aircraft wreckage. The FAA inspector reported to the NTSB that in an examination of the tail rotor drive train, he found no evidence of malfunctions from the tail rotor forward to the quill shaft. The FAA inspector reported that he was unable to evaluate the condition of the quill shaft or main transmission at the site, due to the positioning of the aircraft wreckage. Following recovery of the helicopter wreckage from the accident site, a follow-up wreckage examination was conducted at the facilities of Northwest Helicopters, Olympia, Washington, on or about March 2, 2001. This examination was conducted under the direction of the NTSB investigator-in-charge (IIC) with representatives of Bell Helicopter Textron Incorporated (the original manufacturer of the helicopter for the U.S. military), Grim Logging, and Hagglund Helicopters of Pendleton, Oregon (the FAA type certificate holder for the Western International UH-1H at the time of the accident) present. During this examination, one of the pitch links on the tail rotor hub was found disconnected from the pitch horn on the tail rotor grip. The attaching bolt, nut, cotter key and washers associated with the disconnected tail rotor pitch link were missing and were not located. No other evidence of inflight malfunction of the tail rotor drive train or tail rotor control system was noted. The helicopter's main transmission exhibited rotational continuity from the power input shaft through to both the main rotor and tail rotor output shafts. The section of the tail rotor driveshaft located in the vertical fin exhibited several witness marks around its circumference at a position, and in a pattern, matching the installed position of the tail rotor control chain.

The tail rotor hub, blade grips, and pitch change mechanism were removed from the helicopter as found and the assembly was shipped in its as-found condition to the NTSB Materials Laboratory, Washington, D.C., for further examination. In this examination, an NTSB Materials Laboratory physical scientist examined the damage to the bushing in the disconnected blade grip horn and the spherical bearing from the adjustable end of the disconnected pitch change link. Microscopic examination of the disconnected blade grip horn bushing revealed fretting damage on the surface of the bushing that contacts the spherical bearing of the pitch change link, and on the inside of the bushing through hole. The outer circumference of the bushing had a deformed raised metal lip, which was bent and fractured near the tip of the blade grip horn. The inner circumference of the bushing's contact surface was also deformed near the tip of the blade grip horn. No thread contact marks were seen in the bushing through hole. Microscopic examination of the pitch change link spherical bearing disclosed fretting damage on the surface that contacts the blade grip horn bushing, and on the inside of the bearing through hole. The bearing's outer race was slightly deformed near the rod end. There was a thin circumferential contact mark on the inside of the through hole, about 1/8 inch inward from the bolt head side of the bearing. There were five axial scratches inside the through hole, about 1/4 to 1/8 inch inward from the bolt head side of the bearing. Both of the blade grip horns, and both of the pitch change links, were found to be intact with no visible deformation.

Review of the helicopter's maintenance records disclosed three discrepancy writeups of loose tail rotor pitch change link bolts in an approximately 6-week time frame prior to the accident. The first, on December 30, 2000, at 11,273.6 hours aircraft total time, indicated: "FLT 2 TARGET T/R Blade P/C link inboard bolt loose." The corrective action was recorded as "Retightened and [safetied] bolt", and "INSP OK." The second, on January 11, 2001, at 11,315.1 hours aircraft total time, indicated: "Preflight Inboard bolt on TGT T/R P/C link Loose." The corrective action was given as: "RETORQUED INBRD NUT ON TGT T/R P/C LINK I/A/W TM 55-1320-210-23 M.M." The last of these writeups, on February 2, 2001, at about 11,405.5 hours aircraft total time, indicated: "Bolt on T/R crosshead Loose." The corrective action was again listed as "Torqued + safetied Bolt."

An autopsy on the pilot was performed by the Montana State Medical Examiner at the Montana Division of Forensic Science, Missoula, Montana, under the authority of the Ravalli County, Montana, Deputy Coroner on February 8, 2001. The autospy determined the cause of the pilot's death to be "Multiple blunt force injuries" and the manner of the pilot's death to be "Accident." Toxicology tests were performed by the FAA Civil Aeromedical Institute (CAMI), Oklahoma City, Oklahoma. The CAMI toxicology tests screened for carbon monoxide, cyanide, ethanol, and drugs, and did not detect any of these substances.

NTSB Probable Cause

Inflight loss of a tail rotor pitch change link-to-blade grip attach bolt, resulting partial loss of tail rotor control, and subsequent entanglement of the helicopter's external load cable with a tree during emergency descent. Factors included the pilot's retention of external load equipment, and the tree in which the external load cable became entangled.