GAA15LA131

The pilot’s inadequate preflight planning and his subsequent decision to attempt to climb over rising terrain with the helicopter over maximum gross weight while operating in high-density altitude conditions with a tailwind, which resulted in its inability to maintain a positive climb rate and a subsequent impact with terrain.

According to the private pilot, he and his passenger departed a friend's property for the personal flight after refueling. He reported that, as the helicopter was flying up a canyon and climbing in rising mountainous terrain with elevations exceeding 7,500 ft, he noticed a substantial tailwind gust, followed by a decrease in airspeed below effective translational lift. The helicopter stopped climbing, and the pilot immediately made a left turn with the intention of reversing course and turning into the wind. After turning left about 90 degrees, the pilot noticed a change in engine noise, heard the low rotor rpm warning horn, and "dropped the collective" as he continued to try to turn into the wind and regain rotor rpm as the helicopter was about 50 ft above ground level. The pilot was unable to increase the rotor rpm, and the helicopter impacted the rising terrain, which resulted in substantial damage to the fuselage and tailboom. The investigation determined that the helicopter was operating about 30 lbs above its approved maximum gross weight and that the calculated density altitude was about 9,600 ft. It is likely that the pilot did not adequately plan for the flight, which resulted in his taking off with the helicopter over its gross weight and operating in high-density altitude conditions with a tailwind and in the helicopter's subsequent inability to maintain a climb and its impact with rising terrain.

: **This report was modified on July 28, 2016. Please see the docket for this accident to view the original report.* On July 12, 2015, about 1300 mountain daylight time, a Robinson R22 Beta II helicopter, N441MM, the helicopter was substantially damaged when it collided with rising terrain 10 miles west of Escalante, Utah. The pilot sustained serious injury and his passenger sustained minor injury. The helicopter was registered to Cornerstone Management in Newark, Delaware, and operated by the pilot as a day, visual flight rules, personal flight under 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed at the time of the accident and no flight plan was filed. The helicopter departed private property near Escalante, about 1230. According to the pilot, he had departed a friend's property after refueling. He reported that, as the helicopter was traveling up a canyon and climbing in rising mountainous terrain, he noticed a substantial tailwind gust. He reported that the helicopter's airspeed had decreased below Effective Translational Lift (ETL) and that the helicopter had stopped climbing. The pilot reported that he immediately made a left turn with the intention of reversing course and subsequently turning into the wind. The pilot reported that after turning left approximately 90 degrees, he noticed a change in engine noise, he heard the Low Rotor RPM Warning Horn, and "dropped the collective" to regain rotor rpm as he continued to try to make the turn into the wind, but the helicopter was about 50 ft above ground level (AGL). The pilot said that he was unable to regain the decreased rotor rpm and the helicopter impacted the terrain. The helicopter sustained substantial damage to the fuselage and tailboom. The terrain elevation at the accident site was 7,461 feet, and the temperature at the time of the accident was 75 degrees Fahrenheit (F). The Pressure Altitude (PA) was 7,011 ft. and the density altitude (DA) was 9,600 ft. The calculated gross weight of the helicopter at the time of the accident was 1,400.42 pounds. Per the Robinson 22 Pilot Operating Handbook (R22 POH), maximum allowable gross weight was 1,370 pounds. Per the R22 POH, the maximum weight when operating at 7,011 ft. PA and 75 degrees F is 1,275 pounds. The pilot reported that he executed an immediate left turn after experiencing a tail wind gust. According to the manufacturer, when the R22 main rotor RPM falls below 515 RPM, the low rotor RPM horn sounds. Subsequently the main and tail rotor inertia decreases rapidly and the helicopter descends, or airspeed is traded for altitude. According to the pilot, when he heard the low rotor RPM horn he lowered the collective and the helicopter impacted the ground and came to rest on its left side facing west. ADDITIONAL INFORMATION According to the Federal Aviation Administration (FAA) Helicopter Flying Handbook FAA-8083-21A (HFH) (pg. 2-4, para. 5), turns in a helicopter increase the load factor exponentially, ultimately increasing the power requirement that is necessary to maintain the helicopter's altitude. Left pedal turns increase the quantity of anti-torque produced by the tail rotor, by demanding additional power from the 124 brake horsepower engine. Pilot flight control inputs demanding more power than the engine is capable of producing, with respect to the atmospheric conditions, adversely affects the helicopters ability to sustain its altitude. Available engine power is directly correlated to main and tail rotor RPM. When the engine fails to produce the required power to sustain airspeed and altitude at high DA, the main rotor blades will exceed their critical angle of attack, consequently decreasing main rotor blade RPM. According to the FAA Helicopter Flying Handbook FAA-8083-21A, Chapter 7 (pg. 7-2, para. 5) per the section entitled Factors Affecting Performance: A helicopter's performance is dependent on the power output of the engine and the lift produced by the rotors, whether it is the main rotor(s) or tail rotor. Any factor that affects engine and rotor efficiency affects performance. The three major factors that affect performance are density altitude, weight, and wind. DENSITY ALTITUDE According to the PHAK, Chapter 3 (pg. 3-3, para. 1) per the section entitled Density Altitude (DA): DA is the vertical distance above sea level in the standard atmosphere at which a given density is to be found. The density of air has significant effects on the aircraft's performance because as air becomes less dense, it reduces: • Power because the engine takes in less air. • Thrust because a propeller is less efficient in thin air. • Lift because the thin air exerts less force on the airfoils. Per the Robinson Helicopter Pilot Operating Handbook (Section 5 – Performance): Relevant meteorological data was used to estimate the DA and PA at the time of the accident. The DA was 9,600 ft. and the PA was 7,011 ft. The PA combined with temperature and weight, were used to determine in ground effect (IGE) and out of ground effect (OGE) capability, per the POH. According to the R22 POH, Chapter 5 (pg. 5-6) the R22 Beta II was capable of conducting IGE flight at the maximum approved gross weight of 1370 pounds and a temperature of 75 degrees F, with the maximum IGE capability at 7,800 ft. PA. The maximum OGE capability under the same conditions was 3,500 ft. PA. According to the United States Army Field Manual 1-203 (Task 1016), OGE maneuvers include, amongst others: terrain flight, terrain flight approach, terrain flight decelerations. The pilot reported that his airspeed decreased below that of ETL prior to executing the left turn. He further asserted that the helicopter was approximately 50 ft. AGL when the left turn was executed. The Height/Velocity Diagram in the R22 POH, Chapter 5 identifies that the pilot shall avoid operating the helicopter at airspeeds below 24 KIAS at altitudes between 10 and 50 ft. above ground level (AGL). When flying above 7,000 ft. DA, weighing 1,300 pounds, the area that pilots shall avoid operating within increases from 10 to 510 ft. AGL. WEIGHT Per the FAA Aircraft Weight and Balance Handbook FAA-H-8083-1A (pg. 1-1, para. 2), per the section entitled Weight Control: Improper loading cuts down the efficiency of an aircraft from the standpoint of altitude, maneuverability, rate of climb, and speed. It may even be the cause of failure to complete the flight, or for that matter, failure to start the flight. Because of abnormal stresses placed upon the structure of an improperly loaded aircraft, or because of changed flying characteristics of the aircraft, loss of life and destruction of valuable equipment may result. The responsibility for proper weight and balance control begins with the engineers and designers, and extends to the aircraft mechanics that maintain the aircraft and the pilots who operate them. According to the FAA Helicopter Flying Handbook FAA-8083-21A (pg. 2-4, para. 5 and 6), per the section entitled Weight: The weight of the helicopter can also be influenced by aerodynamic loads. When you bank a helicopter while maintaining a constant altitude, the "G" load or load factor increases. The load factor is the actual load on the rotor blades at any time, divided by the normal load or gross weight (weight of the helicopter and its contents). Any time a helicopter flies in a constant altitude curved flightpath, the load supported by the rotor blades is greater than the total weight of the helicopter. Above 30° of bank, the apparent increase in gross weight soars. At 30° of bank, or pitch, the apparent increase is only 16 percent, but at 60°, it is twice the load on the wings and rotor system. For example, if the weight of the helicopter is 1,600 pounds, the weight supported by the rotor disk in a 30° bank at a constant altitude wo