History of Flight
On January 22, 2016, at approximately 1100 Pacific standard time, a Robinson R22 Beta, registration N7020U, was substantially damaged when a student pilot lost control during a transition from hover taxi to climbing departure near Las Vegas, Nevada. The solo instructional flight was conducted under 14 CFR Part 91 in visual meteorological conditions without a flight plan. The pilot, who received minor injuries, reported that the helicopter was rented from a fixed base operator and Part 61 flight school at North Las Vegas Airport (VGT).
The pilot planned to practice maneuvers at a water retention basin about 10 miles northwest of VGT, a normal practice area. A concrete levee about 50 feet high bounded the east side of the basin. The levee was oriented north-south with a roadway on top and a west wall sloping about 25 degrees from horizontal.
After a normal preflight and engine start, the pilot departed VGT at about 1040 and proceeded to the practice area. He intended to practice normal approaches to a pinnacle landing. He flew a right traffic pattern over the levee to verify wind direction, confirmed southerly winds, and flew a northbound right downwind at about 500 feet agl and 65 knots. He descended on a base leg at about 300 fpm, decelerating on final, and brought the helicopter into a hover taxi about 10 feet above the levee.
The pilot then pushed forward on the cyclic to begin a climb out. The helicopter yawed to the right; despite full left pedal input, the yaw continued. The pilot rolled off the throttle and lowered the collective. The helicopter continued its right spin, drifting west over the sloped levee. The pilot then gradually raised collective to reduce descent rate before ground contact. The helicopter made a hard landing and remained upright. The pilot shut down and called his flight instructor. No engine anomalies or low rotor rpm light were observed.
Personnel Information
The pilot held a student pilot certificate with approximately 50 total flight hours, all in Robinson helicopters, including about 7 hours solo in the R22. He received his solo endorsement in December 2015. His most recent FAA first-class medical certificate was issued in June 2015.
Aircraft Information
The Robinson R22 Beta (N7020U) was manufactured in 1998 and equipped with a Lycoming O-360 series engine. The main rotor rotates counter-clockwise; the tail rotor counteracts nose-right torque. The most recent inspection (100/300 hour) was completed on December 22, 2015, at a total time of about 8,240 hours. The most recent annual inspection was on October 8, 2015, at about 8,045 hours. Maintenance records show a right magneto overhauled and installed on July 17, 2015. A governor motor assembly was replaced in November 2014.
Meteorological Information
The 1053 VGT automated observation reported winds from 140 degrees at 6 knots, visibility 10 miles, clear skies, temperature 13°C, dew point -6°C, altimeter 30.21 inches of mercury. The flight instructor and an FAA inspector noted that the flood basin area was subject to unpredictable winds due to topography and heating as the day progressed.
Wreckage and Impact Information
The accident occurred on the roadway atop the levee, about 8.6 miles from VGT on a bearing of about 305 degrees. The helicopter came to rest upright, facing uphill, about two-thirds down the sloped levee wall. Scrape marks were limited to the slope. Both skids were deformed upward, reducing ground clearance to about 25% of original. The cabin volume was not compromised. The main rotor system was undamaged. The tail boom-fuselage junction was deformed and partially fractured. Both tail rotor blades were fracture-separated at about one-quarter span, consistent with loads in the plane of rotation. The lower vertical stabilizer was scraped and bent right, consistent with ground contact during a right spin. No fuel leaks or fire occurred. An examination found no preimpact mechanical malfunctions.
Additional Information
Post-recovery examination at VGT revealed the tail rotor pedals had full travel, push rods were secure, and all controls moved freely. A minor anomaly in the gearbox compartment showed a one-time contact between the forward bell crank and firewall, but it did not impede movement. The tail rotor links and blades had full pitch travel. The drive system was intact; main rotor rotated freely with tail rotor rotation in one direction. All drive shaft flex couplings were undamaged. The low rotor rpm warning light bulb had an intact filament.
Three components (governor controller, magneto, governor motor) were removed and examined at Robinson Helicopter Company. All met functionality criteria except the magneto's tachometer points had a gap of less than 0.012 inches (specification 0.019+.003), but the points were undamaged. A visual inspection of the governor controller found no internal abnormalities; bubbled paint on the exterior was attributed to a manufacturing event.
The Helicopter Flying Handbook describes loss of tail rotor effectiveness (LTE) as an aerodynamic phenomenon that can affect single-rotor helicopters. Conditions at the time were consistent with factors such as airflow turbulence, high power setting, slow forward airspeed, and winds from approximately 285-315 degrees relative to the helicopter.