Bonners Ferry, ID, USA
N55714
Kaman HH-43
During CFR Part 133 aero-logging operations in mountainous terrain, a loaded long-line became caught in some trees and separated from the helicopter. After the ground crew told the pilot what had happened, he began a hover over the site of the line separation, apparently to survey the situation. While in the hover, the pilot allowed the aircraft to move a short distance back and to the side. This put it into a position where its main rotor blades came in contact with a coniferous tree. Although the ground crew transmitted a warning to the pilot to power up and out of the trees, the rotor blades began coming apart before the pilot was able to take corrective action. Soon thereafter the helicopter collided with other trees, and fell to the ground in a nose down position.
On September 25, 2001, approximately 1500 Pacific daylight time, a Kaman HH-43 "Huskie" helicopter, N55714, impacted trees while hovering over a logging pick-up site about 12 miles north of Bonners Ferry, Idaho. The commercial pilot, who was the sole occupant, received fatal injuries, and the aircraft, which is owned by Horizon Helicopters and operated by Precision Helicopters, sustained substantial damage. The 14 CFR Part 133 long-line aerial logging flight, which had been in the air for about 15 minutes, was being operated in visual meteorological conditions. The flight was not being conducted under a filed flight plan. The ELT, which was activated by the accident sequence, was turned off at the scene. According to witnesses, shortly before the accident, a load of logs that was being lifted by the helicopter became snagged in a tree in steep mountainous terrain. The excess load caused by the snagged long-line resulted in the shearing of the bolt that holds the long-line to the helicopter. After the long-line separated from the aircraft, the ground crew advised the pilot what had taken place, and he then hovered over the area for about two minutes. To the witness on the ground, it appeared that the pilot was looking over the situation and trying to determine what had happened and how to address the problem. As the helicopter continued to hover, it appeared that it moved a short distance back and to the right. This put it into a draw "...where the trees were taller than what was on the main slope." Soon thereafter, the ground crew heard the "wop wop" of the rotors striking a tree. About the same time, one crew member saw the rotor blades contacting "...a green Fir or Larch tree." That crew member, who had radio contact with the pilot, told him to "...power up and out because of the blade strike." But, according to the witnesses, before the pilot was able to take corrective action, the rotor blades began to "fly apart." The helicopter then started to come in contact with additional trees, and as its rotors failed, it fell to the terrain, impacting in a nose-down attitude. According to the ground crew, until they heard the sound of the rotors impacting the tree, there had been no unusual engine or rotor noises. The pilot did not make any radio transmissions indicating he had encountered any problems, and a post-accident inspection of the aircraft found no apparent anomalies in the airframe, powerplant, or flight control system. An autopsy performed by Pathology Associates Inc., of Spokane, Washington, determined that the cause of death was due to blunt impact forces to the chest. A forensic toxicology completed by the Federal Aviation Administration's Toxicology and Accident Research Laboratory proved negative for carbon monoxide, cyanide, ethanol, and listed drugs.
The pilot's inadequate visual lookout which lead to his failure to maintain clearance from the nearby trees while in a high-hover. Factors include mountainous/hilly terrain, and tall trees in the area where the helicopter was hovering.
Source: NTSB Aviation Accident Database
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