NTSB Identification: FTW01LA121.
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Accident occurred Friday, May 18, 2001 in Houston, TX
Probable Cause Approval Date: 09/27/2001
Aircraft: Eurocopter AS-350-B2, registration: N311TV
Injuries: 1 Minor.

NTSB investigators may have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

The helicopter was on final approach, approximately 15 feet above the roof top helipad, when the helicopter's controls "became very stiff." The pilot observed the "HYD" light on the caution panel illuminated; however, the audible hydraulic warning horn did not activate. Subsequently, the helicopter impacted the helipad with the right skid, and rolled onto its right side. Examination of the helicopter's cockpit revealed that the hydraulic cut-off switch, which is located on the collective control, was found in the cut-off position and its red plastic guard was broken (when the switch is in the cut-off position the hydraulic warning horn will not sound). The cockpit was examined for shattered pieces of the guard; however, none were found. The hydraulic system was examined and no leaks were noted. A functional test of the hydraulic pump and regulator/manifold revealed no anomalies with either unit.

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

the failure of the pilot to maintain control of the helicopter following an inadvertent deactivation of the hydraulic system, during final approach. A contributory factor was the unguarded hydraulic cut-off switch.

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