NTSB Identification: ANC02FA029.
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Nonscheduled 14 CFR
Accident occurred Thursday, April 11, 2002 in Valdez, AK
Probable Cause Approval Date: 04/29/2003
Aircraft: Eurocopter AS-350-B2, registration: N917JT
Injuries: 7 Uninjured.
NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.
The pilot of the helicopter was returning to a remote lodge with six skiers aboard. While in cruising flight, the hydraulic pressure warning light on the enunciator panel illuminated, and the aural warning horn sounded, indicating a loss of hydraulic pressure. The pilot confirmed the loss of hydraulic pressure, and slowed the forward airspeed of the helicopter. He cycled the hydraulic cut-off switch on the collective lever by turning the system off momentarily, and then on again. The pilot made a landing pattern and approach to a road, and brought the helicopter to a hover above the road. After coming to a hover the helicopter rolled hard left, and impacted the terrain inverted. According to the helicopter's operator manual, upon loss of hydraulic pressure, the pilot should reduce collective pitch to reduce the airspeed, disengage the collective pitch hydraulic pressure switch, make a flat approach, and land with forward airspeed. An inspection of the helicopter revealed that the hydraulic pump drive belt separated at the point where the belt is bonded together. The separation of the belt resulted in a total loss of hydraulic pressure. The belt is the subject of repeated maintenance inspection and has a life limit of 600 hours of operation. The failed belt had been in operation on the accident helicopter about 419 hours.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The pilot's failure to disengage the hydraulic system, and maintain forward airspeed during landing as delineated in the emergency procedures section of the helicopter's operations manual, which resulted in a loss of control while hovering. Factors contributing to the accident were the separation of the hydraulic pump drive belt, and the subsequent lockup of the flight control system. Full narrative available
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