Accident Summary
On January 13, 2020, about 1350 mountain standard time, a Hughes 269C helicopter, registration N7480F, was substantially damaged when it struck terrain during a training flight near Spanish Fork, Utah. The aircraft was operated as a 14 Code of Federal Regulations Part 91 instructional flight. The instructor and the pilot receiving instruction were not injured.
Flight Sequence
The pilot receiving instruction stated he was preparing for his rotorcraft certificate and practicing for his checkride. After an uneventful preflight inspection and engine start, the engine run-up was performed at 2,500 rpm. The pilot reduced engine power to idle and observed normal rotor and engine rpm separation. Following departure, the helicopter entered the airport traffic pattern, performed several landings and three autorotative maneuvers. The flight then departed the pattern to a practice area west of the airport, where two recoveries from settling with power were performed before returning to the airport.
During cruise flight at 6,500 ft mean sea level, about 1,500 ft above ground level (agl), the instructor announced a simulated engine failure. The pilot receiving instruction decreased power to idle and lowered the collective to enter an autorotation. As the helicopter descended to 500 ft agl, the instructor advised the pilot to recover, but they realized the engine had stopped producing power. At about 200 ft agl, the instructor took control; the rate of descent was estimated at 1,600 ft per minute. The instructor initiated a flare below 30 ft agl to reduce airspeed and rate of descent, then raised the collective to cushion the landing. The helicopter had about 7 mph of forward movement when it contacted soft ground. The helicopter nosed over, the main rotor blades contacted the tailboom (which separated), the front right skid tube broke, and the helicopter rolled onto its right side before coming to rest.
Checklists and Procedures
An onboard checklist included sections for engine warmup and ground check, and engine cooling and shutdown procedure, condensed from the Pilot's Operating Handbook. The POH specified a check of idle speed at the end of the last flight of each day: the throttle in full override should produce an idle speed of no less than 1,400 rpm, and at the normal idle stop no greater than 1,600 rpm. The POH also contained a warning that to reduce the chance of engine stoppage when initiating practice autorotations, the throttle should not be abruptly retarded to the idle position.
The pilot receiving instruction, a co-owner, stated he performed an engine check before each flight by running the engine to 1,800 rpm and observing gauges, including a magneto check, before reducing throttle and observing rotor and engine rpm split. He said he never reduced throttle below 1,200 rpm during simulated engine failures. The instructor stated the pilot typically reduced power within 1 second during simulated failures. The pilot receiving instruction was not familiar with the POH idle speed check procedure; the instructor reported they followed the onboard shutdown checklist after each flight.
Postaccident Examination
Postaccident examination confirmed control continuity from the anti-torque pedals to the tail rotor and cyclic control continuity to the swashplate. The throttle control moved through its full range; the mixture control operated without discrepancies. The engine drive belts were cut for an engine run test. The engine idled at 500 to 750 rpm, where it ran rough and cut out periodically. According to the POH, the engine should idle between 1,200 and 1,600 rpm. A magneto check at 1,800 rpm showed a drop of about 300 rpm when switching to each magneto individually. The engine ran smoothly at 2,500 rpm.