On August 5, 2008, about 1941 Pacific daylight time, a Sikorsky S-61N helicopter,
N612AZ, impacted trees and terrain during the initial climb after takeoff from Helispot 44
(H-44), located at an elevation of about 6,000 feet in mountainous terrain near Weaverville,
California. The pilot-in-command, the safety crewmember, and seven firefighters were fatally
injured; the copilot and three firefighters were seriously injured. Impact forces and a postcrash
fire destroyed the helicopter, which was being operated by the U.S. Forest Service (USFS) as a
public flight to transport firefighters from H-44 to another helispot. The USFS had contracted
with Carson Helicopters, Inc. (CHI) of Grants Pass, Oregon, for the services of the helicopter,
which was registered to CHI and leased to Carson Helicopter Services, Inc. of Grants Pass.
Visual meteorological conditions prevailed at the time of the accident, and a company visual
flight rules flight plan had been filed.
We determined that the probable causes of this accident were the following actions by Carson Helicopters: 1) the intentional understatement of the helicopter’s empty weight, 2) the alteration of the power available chart to exaggerate the helicopter’s lift capability, and 3) the practice of using unapproved above-minimum specification torque in performance calculations that, collectively, resulted in the pilots relying on performance calculations that significantly overestimated the helicopter’s load-carrying capacity and did not provide an adequate performance margin for a successful takeoff; and insufficient oversight by the USFS and the Federal Aviation Administration (FAA).
Contributing to the accident was the failure of the flight crewmembers to address the fact that the helicopter had approached its maximum performance capability on their two prior departures from the accident site because they were accustomed to operating at the limit of the helicopter’s performance.
Contributing to the fatalities were the immediate, intense fire that resulted from the spillage of fuel upon impact from the fuel tanks that were not crash resistant, the separation from the floor of the cabin seats that were not crash resistant, and the use of an inappropriate release mechanism on the cabin seat restraints.
The safety issues involve the accuracy of hover performance charts, USFS and FAA oversight, flight crew performance, accident survivability, weather observations at helispots, fuel contamination, flight recorder requirements, and certification of seat supplemental type certificates. Safety recommendations concerning these issues are addressed to the FAA and the USFS.
