Accident Summary
On June 27, 2013, at approximately 1930 mountain daylight time, a Robinson R44 helicopter (registration N7187B) was substantially damaged during a forced landing maneuver near Fielding, Utah. The helicopter was being operated by Whirlybird Helicopters of Ogden, Utah, on an instructional flight under 14 CFR Part 91. The student pilot, the sole occupant, was not injured.
Pilot Report
The 44-hour student pilot stated that while entering a canyon, he climbed to about 5,600 feet msl, 100 feet above his planned profile of 5,500 feet. Upon entering the canyon mouth, he reduced speed to 70-75 knots due to turbulence experienced the previous day. Approximately halfway through the canyon, the helicopter dropped about 100 feet, and the main rotor RPM dropped to between 80 and 85 percent. The pilot lowered the collective and added throttle, maintaining 70 knots and turning toward a field. During the turn, RPM increased to about 90 percent but dropped again after leveling out. After clearing a set of wires, the pilot set up for a landing in the field, performed a "baby flare" then a full flare, added pitch, and set the helicopter down. The pilot reported that after landing, the front skid caught, causing the helicopter to tip and roll onto its left side, resulting in substantial structural damage. He reported no preimpact mechanical malfunctions.
Postaccident Inspection
A Federal Aviation Administration airworthiness inspector performed a postaccident engine inspection. Prior to an engine run, sparkplugs from cylinders #1, #3, and #5 were removed and found to contain oil, which the inspector speculated occurred during shipment. The engine was installed on a test stand with a test club propeller. It started without hesitation. During a magneto drop test at 1,800 rpm, the right magneto (serial number E06DA051) produced stumbling symptoms with a drop of 400-425 rpm, while the left magneto (serial number E08GA072R) dropped about 90 rpm. No other anomalies were noted. A subsequent examination of the right magneto at Aircraft Magneto Service revealed minimal oil in the housing but no operational difficulties. The technician found the magneto functioned normally after assembly and testing.
Weather Conditions
At 1956, the weather reporting station at Logan-Cache Airport (LGU), about 11 nautical miles east of the accident site, reported wind variable at 3 knots, visibility 10 miles, sky clear, temperature 36°C, dew point 7°C, and an altimeter setting of 30.20 inches of mercury. Density altitude at the time of the accident was calculated to be 8,830 feet.