History of Flight
On March 26, 2013, about 1245 central daylight time, a Hughes OH-6A helicopter, N910WC, was substantially damaged when it impacted a stock pond at the Walking Cane Ranch, near Caddo, Texas. The private pilot sustained minor injuries and the passenger was fatally injured. The helicopter was registered to SMR Venture, LLC., and was operated by a private individual under 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed, and the flight operated without a flight plan. The local flight originated from Walking Cane Ranch approximately 1215.
A witness located east of the accident location reported that the helicopter flew over him and continued west, then reversed course back to the east and approached a stock pond as if preparing to land in an adjacent field. The witness stated that as the helicopter began to slow down, he felt a strong gust of wind from the north-northwest. The helicopter then started to descend quickly, facing west, in a 45-degree or greater bank angle. The witness looked away and when he looked back, the helicopter continued to descend and started to spin very quickly. It appeared that the main rotor was not moving or was standing still as the helicopter spun. The bank angle increased to nearly 90 degrees. The witness lost sight of the helicopter and did not see it impact the water.
According to the pilot, he approached an open field adjacent to the stock pond where he had landed earlier that day. He looked for smoke or dust to establish wind velocity and direction but did not observe any. As he established a hover approximately 3 to 4 feet above the ground, the pilot sensed a need to turn toward the east-southeast. Subsequently, the helicopter started to spin, and control was lost despite flight control inputs. The helicopter impacted the stock pond on the passenger side and immediately became submerged. The pilot egressed; the passenger did not.
Personnel Information
The pilot, age 75, held a private pilot certificate with helicopter and instrument ratings. He was issued a third-class airman medical certificate on April 9, 2012, with the limitation must wear corrective lenses. He reported 571 total flight hours, with 210.3 hours in the accident make and model. He completed a flight review on November 1, 2012, in the accident helicopter.
Aircraft Information
The helicopter, a Hughes OH-6A (serial number 67-16372), was registered with a standard airworthiness certificate for normal operations. It was powered by an Allison 250-C20C engine rated at 375 horsepower. Maintenance was under an annual inspection program; the last annual inspection was completed on September 5, 2012. The helicopter had 4,756.2 hours at the time of the accident.
Meteorological Information
The closest official weather observation station was Stephens County Airport (KBKD), Breckenridge, Texas, 14 nautical miles west of the accident site. The elevation of the station was 1,284 feet mean sea level. A routine aviation weather report (METAR) for KBKD issued at 1335 reported wind 200 degrees at 6 knots, visibility 10 miles, sky clear, temperature 15°C, dew point minus 8°C, altimeter 30.38 inches.
Wreckage and Impact Information
The accident site was in the middle of the stock pond at GPS elevation 1,348 feet. The helicopter came to rest on its left side and was later pulled to shore by first responders, incurring additional damage to landing skids and fuselage. No ground scars were apparent.
Main wreckage rested on its right side on the south shore. The fuselage, cabin, instrument panel, tail boom, engine, and main rotor assembly were present. The fuselage skin and structure were crushed and wrinkled in multiple locations. The left door separated and was found atop the wreckage. The forward bubble and windscreen were fragmented and separated.
Cabin seats, instrument panel, and flight controls were present. Left fuselage structure was crushed and bent aft and right. Left anti-torque pedals separated from mounting points. Left seat upper frame bent; left collective partially separated. Flight controls were continuous from cabin to rotor, engine, and empennage. Separations were consistent with impact.
Both forward seatbelts remained attached; webbing unremarkable. Right side (pilot) inertia reel functioned; left side was impact-damaged, preventing functional test, but examination revealed no anomalies.
Tail boom remained partially attached via electrical wiring conduit and was submerged. It included horizontal and vertical stabilizers, tail rotor assembly, driveshaft, and gearbox. Stabilizers were unremarkable. Tail rotor blades were mud-covered but otherwise unremarkable. The soft stop on the tail rotor assembly separated and was not located. The tail rotor driveshaft was continuous and rotated correctly when manually actuated.
Main rotor blades 1, 2, and 3 remained attached at the hub/mast; all three were bent and wrinkled. Blade 3 was bowed slightly upward. Blade 4 separated and was found on the east shore.
Examination of the engine and transmission revealed the driveshaft between the main rotor and transmission had separated, consistent with impact overload at a design shear point. The compressor rotated freely. Rotation was observed at the starter/generator and first stage of the gas producer turbine. The power turbine was rotated by hand, with rotation noted at the engine-to-transmission driveshaft and tail rotor driveshaft. Chip detectors, engine oil screen, and engine fuel screen were free of contamination. The fuel control lever indicated 90 degrees, corresponding to a "flight" throttle setting. No anomalies were found that would have prevented the engine from developing designed power.
Survival Aspects
The autopsy on the passenger was performed on March 27, 2013, and concluded cause of death was drowning due to the helicopter accident. The report noted abrasion, bruising, and lacerations on the right forehead and right temple.
According to the pilot, the accident flight was the passenger's first flight with him in that helicopter. Before the flight, the pilot helped adjust the seatbelt and shoulder harness and showed the passenger how to buckle and unbuckle. The passenger subsequently operated the seatbelt without difficulties.