History of Flight
On April 4, 2014, about 1548 mountain daylight time, a Bell 206B III helicopter, N43MA, was substantially damaged during a liftoff attempt at Missoula International Airport (MSO), Missoula, Montana. Both pilots on board received minor injuries. The helicopter was operated by Minuteman Aviation Incorporated (MAI), and the evaluation flight was conducted under Part 91. Visual meteorological conditions prevailed, and no flight plan was filed.
The pilot under evaluation had landed in a field adjacent to the airport, referred to as the "practice area," after a previous flight. The landing surface was dry, level, and consisted of mixed dirt and grass clumps. The approach and landing were into the wind, on a heading of west or approximately parallel to MSO runway 29. After a brief discussion, the chief pilot attempted a liftoff. The CP reported that the right skid felt "stuck" to the ground, and despite efforts, he could not set the helicopter fully back down. The helicopter rolled over onto its right side, sustaining substantial damage to the fuselage, tail boom, and main rotor. The CP shut down the helicopter, and both occupants exited. No pre-rollover mechanical deficiencies or failures were reported or detected in a post-accident examination.
Personnel Information
The chief pilot held a commercial pilot certificate with multiple ratings, including helicopter. He reported about 19,000 total flight hours, with about 5,310 hours in helicopters and about 1,500 hours in the accident helicopter make and model. His most recent flight review was in March 2014, and his most recent FAA second-class medical certificate was in February 2014.
The pilot under evaluation held a commercial pilot certificate with airplane single-engine land and helicopter ratings. She reported about 1,200 total flight hours, with about 1,080 hours in helicopters and about 5 hours in the accident helicopter make and model. Her most recent flight review was in September 2013, and her most recent FAA first-class medical certificate was in July 2013.
Aircraft Information
The helicopter was configured with a single main rotor system and a tail rotor. It was manufactured in 1991 and equipped with an Allison (Rolls-Royce) 250-C20 series turboshaft engine. The helicopter had accumulated about 7,484 total time in service. Its most recent annual inspection was completed on January 27, 2014.
Meteorological Information
The airport had two wind sensor systems. The ATCT sensor, located about 3,600 feet east of the accident location, showed winds from 290 degrees at 10 to 18 knots with gusts up to 22 knots during the relevant period. The ASOS sensor, about 2,500 feet north-northeast, recorded winds between 267 and 298 degrees magnetic at 10 to 17 knots with gusts up to 20 knots in the 5 minutes around the accident. The 1553 automated observation reported winds from 320 degrees at 11 knots, visibility 10 miles, few clouds at 6,500 feet, temperature 11°C, dew point -2°C, and altimeter 29.81 inHg. The CP's report indicated wind from 250 degrees at 13 knots with gusts to 20 knots.
Wreckage and Impact Information
The practice area was 3,000 feet south-southeast of the intersection of runways 7/25 and 11/29, outside the airport perimeter fence. The helicopter came to rest on its right side, oriented approximately 270 degrees magnetic. Substantial damage occurred to the fuselage and tail boom. The main rotor blade assembly fracture-separated from the mast, the cabin deformed, the tailboom bent, and several windows broke. After exiting, the pilots observed a fuel leak and small fire, causing them to move away. The investigation found no information to substantiate or refute the CP's assertion that the right skid became stuck.
Additional Information
The FAA Rotorcraft Flying Handbook (H-8083-21) states that a single-rotor helicopter is susceptible to dynamic rollover when lifting off, and if the critical rollover angle is exceeded, the helicopter rolls on its side regardless of cyclic corrections. Two critical conditions for dynamic rollover are "right side skid down" and "crosswinds from the left," which are applicable to the accident helicopter.