On June 25, 2009, at 1815 Pacific daylight time, a Robinson R22 Beta, N836SH, lost engine power during flight and landed hard near Lewiston, Idaho. Lewis and Clark Aviation LLC was operating the helicopter under the provisions of 14 Code of Federal Regulations Part 91. The certified flight instructor (CFI) and student pilot were not injured. Visual meteorological conditions prevailed and no flight plan was filed for the instructional flight.

According to the CFI, he and the student were in cruise flight for the student’s first instructional flight. During the flight, the rotor rpm dropped suddenly, and the CFI lowered the collective. Then, he rolled on the throttle but did not get a response. The rpm continued to decrease, and the oil light was illuminated as the helicopter impacted the ground. He attempted to do a run on landing but the skids dug into the ground and the helicopter came to rest on its side with the tail boom separated.

In a phone conversation following the accident, the CFI reported that he had applied full carburetor heat about “a couple of minutes” prior to the loss of power. At the accident site, the carburetor control was found approximately 1 inch out from its stop. It is unknown whether the position of the control had moved during the accident sequence.

The Federal Aviation Administration (FAA) accident coordinator examined the helicopter at the accident site and following its recovery. The linkage for the carburetor heat was continuous and functional. The engine was test run on the accident helicopter. No mechanical anomalies were observed during the examinations.

At 1756, the nearest aviation weather reporting facility reported the dew point as 5 degrees Celsius and the temperature as 25 degrees C. According to the FAA’s icing probability chart, icing conditions existed at glide and cruise power at the time of the accident.