Clark Fork, ID, USA
N114DR
Garlick UH-1H
The commercial pilot was conducting long-line logging operations in a restricted category helicopter when witnesses heard what they described as a loud bang. A witness reported that the pilot had just released the fifth load of logs for the morning and was maneuvering, in a turn, and ascending up the hill. As the helicopter ascended, the witness heard the loud bang. Concurrent with the loud bang, the witness stated that he observed pieces of the helicopter, from the area of the tail boom, flying through the air. The helicopter then yawed to the left, just before impacting terrain in a nose low attitude. A search of the surrounding area located several pieces of the tail rotor assembly. The tail rotor blades, yoke assembly, pitch change links, a portion of the slider, crosshead and the distal end of the control shaft were located, as a unit, near the main wreckage. However, the splined barrel portion of the slider, the tail rotor static stop, tail rotor input shaft and tail rotor retaining nut were not found. Detailed examination of the remains of the tail rotor slider assembly revealed that the tail rotor slider lugs had fractured as a result of fatigue; however, because the condition of the missing components is unknown, it could not be determined if the fractured slider assembly was the primary failure of the tail rotor assembly.
HISTORY OF FLIGHT On June 21, 2002, approximately 0515 Pacific daylight time, a Garlick UH-1H (originally manufactured by Bell Helicopter) restricted-category rotorcraft, N114DR, sustained substantial damage after colliding with wooded terrain approximately four miles southeast of Clark Fork, Idaho. The helicopter is owned by Northwest Helicopters of Olympia, Washington, and was being operated as an external-load (logging) flight operation under the provisions of Title 14, CFR Part 133. The commercial pilot, the sole occupant of the helicopter, was fatally injured. Visual meteorological conditions prevailed and no FAA flight plan had been filed for the local flight. A witness to the accident, a certified airframe and power plant mechanic (A&P) who is employed by the operator, reported that the long-line logging operation had commenced approximately 15 minutes prior to the accident, at 0500 local. He reported that the pilot had just released the fifth load of logs for the morning and was maneuvering, in a turn, back up the hill. As the helicopter ascended, the witness heard what he described as a loud bang "…like a stick of dynamite going off." Concurrent with the loud bang, the witness stated that he observed pieces of the helicopter, reportedly from the area of the tail boom, flying through the air. The helicopter then yawed to the left, just before impacting terrain in a nose low attitude. The witness reported that the helicopter's engine continued to run, for approximately 20 seconds, after impacting terrain. PERSONNEL INFORMATION The pilot held a commercial pilot certificate, with a helicopter rating. The pilot's second-class medical certificate was issued on March 11, 2002, and carried a limitation requiring the pilot to possess glasses for near and intermediate vision. The operator of the helicopter reported that at the time of the accident, the pilot had accumulated approximately 14,000 flight hours, including approximately 8,200 hours in make and model, and 86 hours in the 30 days preceding the accident. AIRCRAFT INFORMATION Bell Helicopter, the original manufacturer, delivered the rotorcraft (tail number 66-00792) to the United States Army in 1966. The United States Army retired the aircraft in February of 1995, and it was subsequently converted (June 2, 1995) to a restricted category civil use rotorcraft using FAA type certificate (H13WA) owned by Garlick Helicopters, Inc, Hamilton, Montana. Maintenance records indicated that the airframe total time, at conversion, was approximately 7,148 hours. Maintenance records indicated that an engine change was completed on June 19, 2002, approximately six flight hours prior to the accident. The log entry indicated that following the engine change the mechanic performed a ground run and additional checks in accordance with the Army Technical Manual and noted that the aircraft was found to be in an airworthy condition and approved for return to service. Maintenance records indicated that on June 7, 2002, (total time 13,789 hours) the tail rotor hub and blades were removed, due to a high time condition, and replaced with a serviceable assembly. The aircraft was subsequently returned to service. An additional log entry indicated that a 25-hour inspection was completed on June 19, 2002, at an aircraft total time of 13,852.3 hours. The entry concluded that the aircraft was found to be in an airworthy condition and approved for return to service. At the time of the accident, the helicopter's total time was approximately 13,900 hours. WRECKAGE AND IMPACT INFORMATION Personnel from the NTSB and Federal Aviation Administration accessed the helicopter wreckage on the afternoon of June 21, 2002. The wreckage was located on private forested land at an elevation of approximately 2,238 feet mean sea level (MSL). The helicopter came to rest at 48 degrees, 5.53 minutes north latitude, and 116 degrees, 9.19 minutes west longitude. The sloping terrain was heavily wooded with large conifer trees and areas of dense undergrowth. The main wreckage consisted of the cabin section and tail boom assembly (oriented on a magnetic heading of 140 degrees), cockpit controls and instrumentation, transmission and mast assembly and the main rotor assembly to include the main rotor blades. Extensive deformation and rearward crushing was noted to the frontal area of the cabin area. Upward bending was noted to the forward section of the right skid and both cross tubes (forward and aft) had collapsed. The left and right windshields were shattered and extensive deformation was noted to the frame assembly. The upper deck area of the cabin and transmission cowling, from the rear bulkhead to the front of the cockpit, had collapsed and was resting on top of the cockpit furnishing. The transmission, mast assembly, rotating controls and main rotor assembly had separated as a unit from the main mounting brackets. The unit collapsed in a forward direction and came to rest atop of the main wreckage. The main rotor blades were found attached to their respective blade grips and sustained extensive impact damage and deformation. Full span leading edge damage to the nose block, to include deformation type bending, twisting and gouging, was noted to both blades. Large sections of after body honeycomb material had torn away from the blades and sections of the trailing edge had separated from the main body of the blade assembly. The tail boom assembly and vertical fin were found intact, but sustained significant damage from ground impact and main rotor blade contact. A large slash was noted to the top of the tail boom, just aft of the synchronized elevator assembly. The intermediate (42 degree) gearbox had separated from its respective mounting lugs and was located in the area of the main wreckage debris field. Brass colored material consistent with the nose block of the main rotor blades leading edge was found imbedded in the forward gear splines of the gearbox (Reference Photo 1). Chord wise slashes and deformation was noted to the vertical fin. Representatives from the manufacturer reported that the damage was consistent with heavy contact with the tail rotor. The lower portion of the fractured 90-degree gearbox was found still attached to the vertical fin (Reference Photo 2). The upper portion was later recovered along the wreckage debris field. A search of the surrounding area located several pieces of the tail rotor assembly. The tail rotor blades, yoke assembly, pitch change links, a portion of the slider and the distal end of the control shaft were located, as a unit, approximately 195 feet northeast of the main wreckage. The pitch change links were bent, however, both remained attached to their respective tail rotor blades and crosshead attach points (Reference Photo 3). The attaching lugs of the tail rotor slider were attached to the crosshead; however, the splined barrel portion of the slider had fractured and was not recovered. Both tail rotor blades sustained leading edge and extensive tip damage. Red paint transfers consistent in color with the vertical fin were noted on the leading edges and tips of both tail rotor blades. Several pieces of the tail rotor assembly and associated components were recovered, however, the barrel portion of the tail rotor slider, the tail rotor static stop, tail rotor input shaft and tail rotor retaining nut were not found. MEDICAL AND PATHOLOGICAL INFORMATION Pathology Associates, Inc, of Spokane, Washington, conducted an autopsy on June 21, 2002. According to the postmortem report, the pilot's cause of death was attributed to blunt force injuries. The manner of death was listed as accidental. Toxicology testing was conducted by the FAA Civil Aeromedical Institute (CAMI), Oklahoma City, Oklahoma. According to the postmortem toxicology report, results were negative for carbon monoxide, cyanide, ethanol and illegal drugs. The report indicated that acetaminophen was detected in the pilot's system (see attached report for specific levels). ADDITIONAL DATA AND INFORMATION Following the onsite investigation, the crosshead assembly and remains of the still attached slider (lugs) were shipped to Bell Helicopter, Fort Worth, Texas, for further examination and evaluation. Examination of the remains of the slider assembly revealed that the tail rotor slider lugs had fractured as a result of fatigue. See attached reports from Bell Helicopter and the NTSB Materials Laboratory for further information. Maintenance records indicated that the before mentioned tail rotor slider was installed on May 9, 2002. At the time of installation, the airframe's total time was 13,680.7 hours. The manufacturer of the tail rotor slider could not be determined; however, aircraft records indicated that the vendor for the tail rotor slider was HY Ness Company of Cranbury, New Jersey. National Transportation Safety Board records show that, N114DR (formerly N85NW) was involved in an accident near Colville, Washington, on June 3, 1997. The accident report concluded that the cause of the accident was attributed to "The in flight failure of the K-FLEX engine-to-gear box drive shaft and no suitable site in which to make a forced/emergency landing." At the time of the accident, the airframe total time was 8,782 hours. At the conclusion of the investigation, the aircraft wreckage and maintenance records were released to PAC Northwest, Redmond, Washington.
A failure of unknown origin in the tail rotor drive assembly. Factors include mountainous terrain unsuitable for an emergency landing.
Source: NTSB Aviation Accident Database
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