NTSB Identification: WPR13LA295
14 CFR Part 91: General Aviation
Accident occurred Thursday, June 27, 2013 in Fielding, UT
Probable Cause Approval Date: 07/30/2014
Aircraft: ROBINSON HELICOPTER R44, registration: N7187B
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.
The student pilot reported that, upon entering the mouth of a canyon, he slowed the helicopter to between 70 and 75 knots because he had experienced turbulence going through the canyon with his instructor the day before the accident. About halfway through the canyon, the helicopter dropped about 100 feet, and the main rotor rpm was between 80 and 85 percent. He lowered the collective and rolled on the throttle to regain rotor rpm and then turned toward a field to set up for a precautionary landing. During the turn, the main rotor rpm rose to about 90 percent, but, after leveling out, the pilot observed the rpm decrease again to between 80 and 85 percent. The pilot stated that, after he cleared a set of wires and landed the helicopter in the field, the front skid caught on something, and the helicopter tipped over on its left side, which resulted in substantial damage. The calculated density altitude at the time of the accident was 8,830 feet, which could have reduced the available engine torque and, subsequently, the rotor rpm. A postaccident examination of the helicopter’s engine and airframe revealed no anomalies that would have precluded normal operation.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The pilot's failure to maintain rotor rpm while traversing a canyon in high-density altitude and gusting wind conditions. Full narrative available
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