History of Flight
On August 7, 2018, at approximately 1000 Pacific daylight time, a Bell 206B helicopter, registration N607RA, struck the ground during an agricultural spray run near Basin City, Washington. The flight was conducted under Title 14 Code of Federal Regulations Part 137 as an aerial application operation. Visual meteorological conditions prevailed, and no flight plan was filed. The flight originated from a landing zone adjacent to the field.
The pilot described the flight as a "rinse load" intended to clean the chemical hopper with water. After taking off with 60 gallons of water and about 25 gallons of fuel, he sprayed the north end of the field for 3 to 4 seconds, then proceeded to the east end. Entering the field at 50–55 mph, he activated the sprayer, then turned it off and initiated a climb. At midfield, at roughly "power pole height" and 50 mph, the pilot applied left tail rotor pedal and lowered the collective to look left at the spray pattern. Immediately after, the helicopter yawed rapidly left and began shaking. The pilot raised the collective and applied right pedal, but the shudder continued. He observed low airspeed and descent. When the helicopter was 5–10 ft above ground, he attempted to level the pitch before the skids contacted. The torque gauge indicated about 108–110%. The pilot did not recall hearing or seeing low rotor RPM warnings. With a forward speed of about 3–5 mph, the helicopter struck the ground, and fire erupted. The pilot exited, then reached back in to close the throttle and shut off the fuel valve. He retrieved his mobile phone and moved away. The pilot estimated the event lasted 10–15 seconds. The loading assistant arrived in a water truck within 10 minutes, but attempts to extinguish the fire were unsuccessful.
Personnel and Aircraft Information
FAA records indicated the pilot held commercial and flight instructor certificates with rotorcraft-helicopter and instrument-helicopter ratings. He had approximately 950 total flight hours, including 900 hours in helicopters and 600 hours in the accident make and model. His most recent flight review was completed in November 2017, and his most recent FAA second-class medical certificate was issued in January 2018.
The helicopter, manufactured in 1971, was equipped with a Rolls-Royce 250-C20B turboshaft engine and registered to Ranger Aviation Leasing in March 2015. The pilot reported the maximum gross weight was 3,200 lbs, and the helicopter weighed about 2,950 lbs at the time of the accident. Power margins were 100% torque for 5 minutes and 85% torque for continuous operation.
Meteorological Information
The automated weather observation at a nearby station at 0953 reported calm winds, temperature 27°C, and dew point 9°C. The operator's accident form indicated wind from 130° at 3–5 knots from an unspecified internet source.
Wreckage and Impact Information
The helicopter came to rest upright and was mostly consumed by fire. Post-recovery examination revealed thermal damage to most components not consumed by fire. Firefighting water and irrigation system exposure caused post-accident corrosion. The main rotor mast was fractured below the hub; both main rotor blades remained attached but were damaged, with bending, fractures, and missing tips. The transmission sustained thermal damage but manual rotation demonstrated drive continuity; chip detectors had no particulate. Tail rotor blades remained attached, one with a missing tip consistent with ground impact. Flight controls were largely consumed by fire. The engine exhibited significant corrosion due to post-accident exposure. Borescope examination found no pre-impact mechanical anomalies or failures. Metal slivers from the engine inlet plenum were consistent with impact-related flexure and ingestion. Lubrication system components were consumed, but the oil filter was clear. No evidence precluded engine power delivery.
Additional Information
Maintenance records were partially burned and water-soaked; some duplicates were provided. The latest dated record was from March 3, 2018, with a Hobbs time of 972.9 hours and total time in service of 17,687.7 hours. An undated page showed a Hobbs time of 1,012.1 hours. The in-service times at the time of the accident could not be determined.