N7176S

On May 24, 2003, approximately 1530 mountain daylight time, a Robinson Helicopter R22 Beta, N7176S, registered to the flight instructor and doing business as Silver State Helicopters, was substantially damaged when it impacted terrain at 6800 South Airport Road, West Jordan, Utah. The flight instructor and the private pilot receiving instruction were not injured. Visual meteorological conditions prevailed, and no flight plan had been filed for the instructional flight being operated under Title 14 CFR Part 91. The flight originated in West Jordan approximately 1505.

According to the accident report submitted by the flight instructor, they remained in the left-hand traffic pattern and were practicing landings on taxiway Bravo, parallel to runway 34. On the third circuit, the instructor asked the student "what would be his reaction if the engine quit on [the] downwind [leg]." At this point they "entered an autorotation by lowering the collective full down and rolling throttle off" into the idle position. They were at 5,200 feet msl (mean sea level) or 600 feet agl (above ground level). Airspeed was 75 knots. The student turned the helicopter 180 degrees into the wind but lost 15 knots of airspeed and rpm (revolutions per minute) dropped to 96 percent. The instructor noticed the rpm drop and added power, but there was no increase in rpm. Altitude had dropped to 4,900 feet msl (300 feet agl), and the rate of descent was increasing. The instructor kept the collective control down and pulled back on the cyclic control to transfer speed into rotor rpm and altitude. RPM and rate of descent stabilized. The instructor said the "[engine and rotor rpm] needles were married at 93% and 95%." He increased collective to reduce the rate of descent. The throttle was fully open. The low rotor rpm horn never shut off and there was no audible increase in rpm. The instructor said that as they passed 50 feet agl, the rpm was so low that "the helicopter was close to stall." He leveled off, but the helicopter struck the ground and bounced several times, collapsing the skids. It rolled over on its left side, shearing off the main rotor and tail rotor blades. The fuselage skin was also wrinkled.

FAA inspectors examined the helicopter and found nothing that would have precluded the development of engine power. They also interviewed the instructor. This was the student's first attempt at an autorotation. FAA concluded that the instructor should have had the student make a straight ahead autorotation instead of a turning autorotation. The student allowed rpm to drop that would have been difficult, if not impossible, to recover.