Accident Summary
On March 20, 2019, about 1610 central daylight time, a Robinson R22 Beta II helicopter (N7782H) sustained substantial damage during an emergency landing to a field near Madill, Oklahoma. The pilot was not injured. The helicopter was owned and operated by Rocking R Enterprises under Title 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed, and the flight was not on a flight plan. The flight departed Madill Municipal Airport (1F4) at about 1600 and was en route to Ardmore Municipal Airport (ARD).
Pilot Report
The pilot reported a preflight that included checking the condition of the V-belts driving the rotor, which appeared normal with proper deflection (approximately 1½ inches). About 10 minutes after takeoff, while in level flight at 700–800 ft above ground level, the clutch warning light illuminated. He entered an autorotation intending to perform a power recovery near the ground. However, within a "short second or two" after the clutch light illuminated, he heard a "bang" and felt the helicopter shudder. He continued autorotation and landed in a rough pasture. The helicopter rolled onto its left side, sustaining substantial damage to the tail boom, main rotor, and fuselage.
Examination Findings
Post-accident examination revealed no preexisting anomalies to the engine, rotor system, or flight controls. However, one of the two double V-belts was missing, and one belt of the other double V-belt was also missing. These were not located at the accident site. The remaining V-belt was displaced from the upper sheave and found hanging on the output shaft. Black rubber marks were found on the clutch actuator, forward face of upper sheave, centering strut, and frame tubes adjacent to the V-belt grooves. A field repair was found on the wire connections at the clutch actuator fuse holder: terminals were wrapped in tape and a wire tie. When removed, the fuse holder terminal fell off, fractured from the holder, and the wires separated from a solder blob. The clutch actuator fuse was a 2-amp fuse instead of the specified 1.5-amp fuse. The extension limiter was measured at 1.65 inches (maximum extension limit), whereas the normal range was 1.1–1.3 inches.
Maintenance History
The last annual maintenance inspection was performed on December 5, 2018, at a helicopter total time of 6,438.2 hours and an hour meter reading of 4,243.9 hours. At the accident site, the hour meter read 4,259.4 hours, indicating 15.5 hours of operation since the last annual inspection.
Relevant Handbook Information
The Robinson R22 Series Pilot Operating Handbook states that the clutch actuator couples the engine to the rotor drive system via V-belts tensioned by raising the upper drive sheave. The clutch caution light illuminates when the actuator is energized. It cautions: "Never take off while clutch light is on." Additionally, the handbook notes that the clutch light may come on momentarily during run-up or flight (3–6 seconds) for belt retentioning. If the light flickers or stays on longer than 10 seconds in flight, the pilot should pull the CLUTCH circuit breaker and land as soon as practical, reducing power and landing immediately if there are other indications of drive system failure.