Flight and Accident Details
On June 6, 2013, at 1730 central daylight time, a Robinson Helicopter Company model R22 Beta helicopter, registration N137DF, was substantially damaged during a collision with terrain near New Braunfels, Texas. The commercial pilot was not injured, but the passenger sustained minor injuries. The helicopter was registered to Davis Pharmaceutical Consulting and operated by Bratcher Aviation under 14 Code of Federal Regulations Part 91, without a flight plan. Day visual meteorological conditions prevailed for the local sight-seeing flight, which departed from a private residence near New Braunfels at about 1715.
The pilot reported that the helicopter had been trailered to the residence of the passenger, who had contracted the sight-seeing flight. After departure, the flight made several passes over the passenger's property and a nearby cornfield at an altitude of about 500 feet above ground level (agl). The pilot stated that after completing a low pass over the cornfield, he entered a climbing right turn to return to the passenger's property. Shortly after establishing the climbing turn, he heard the engine sputter and experienced a reduction in both engine and main rotor speed. The pilot entered an autorotation because the helicopter did not have enough altitude to fully recover from the loss of both engine and rotor speed. The helicopter bounced during the initial collision with terrain before tumbling through the cornfield, damaging about 100 feet of corn.
Investigation Findings
An on-scene investigation was conducted by inspectors from the Federal Aviation Administration (FAA). The examination revealed that the helicopter had entered the cornfield in a level attitude, bounced, and then went over onto its side. Flight control continuity was confirmed for the collective and cyclic systems from the cockpit controls to the main rotor swashplate assembly. The tail rotor control tubes were fractured where the tailboom had separated from the fuselage. Engine throttle control was confirmed from the cockpit to the engine. The main and auxiliary fuel tanks contained about 10 gallons and 2.5 gallons of aviation fuel, respectively. No evidence of a fuel leak was found at the accident site.
Engine Testing
The wreckage was recovered to a storage facility for an operational engine test run. On August 16, 2013, the engine was test run under the supervision of a National Transportation Safety Board (NTSB) investigator. The investigator reported that the damaged main transmission drive belts had to be removed to facilitate the test run; the observed belt damage was consistent with impact damage. The engine started without hesitation and responded to throttle movements throughout the test run. The lack of main transmission belts prevented operating the engine at full power, but no anomalies were noted while operating at various engine speeds. A magneto check confirmed that both magnetos were operational. A differential pressure test indicated that all six cylinders had compression values at or above 76 pounds per square inch (psi) with a reference pressure of 80 psi. The test run and examination did not reveal any anomalies that would have prevented normal engine operation.
Weather Conditions
The nearest aviation weather reporting station was at New Braunfels Regional Airport (KBAZ), New Braunfels, Texas, about 5 miles north of the accident site. At 1751, the KBAZ automated surface observing system reported a variable wind direction at 4 knots, visibility 10 miles, clear sky, temperature 33 degrees Celsius, dew point 19 degrees Celsius, and an altimeter setting of 29.77 inches of mercury. The airport elevation was 651 feet mean sea level. The calculated density altitude was 3,302 feet.