NTSB Identification: SEA07LA154.
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Accident occurred Tuesday, June 12, 2007 in Biggs, CA
Probable Cause Approval Date: 09/27/2007
Aircraft: Bell UH-1B, registration: N2087S
Injuries: 1 Uninjured.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

As the helicopter lifted off from the top of a chemical truck the pilot heard a faint whining sound, which got louder and then abruptly stopped when the helicopter had cleared the truck. After the whining stopped, the helicopter flight controls locked up, but despite the restriction the pilot managed to pull a small amount of aft cyclic to help the helicopter settle to the ground. On touchdown the helicopter drifted to the right, then skidded across the ground before experiencing a dynamic rollover. The pilot reported that the hydraulic pump, which supplies hydraulic power to the flight control system servos, failed. A postaccident examination of the hydraulic pump, which sustained impact damage as result of the accident sequence, failed to reveal why the pump had failed. An FAA inspector reported that the hydraulic pump had been removed from a salvaged helicopter in 2000, and had not been used prior to being installed on the accident aircraft, about a month and a half before the accident. The inspector also reported that the pump's condition was unknown and that it was never tested prior to being installed on the helicopter.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

Loss of control during hover for undetermined reasons.

Full narrative available

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