Accident Details
On September 2, 2009, at approximately 1040 central daylight time, a single-engine Hughes 269 helicopter, registration N58163, was substantially damaged during a landing following a precautionary autorotation. The pilot and flight instructor on board were not injured. The helicopter was registered and operated by a private individual. Visual meteorological conditions prevailed at the time, and no flight plan was filed for the 14 Code of Federal Regulations Part 91 cross-country flight.
Events
According to a statement submitted by the flight instructor, while in cruise flight, they heard a loud noise and the pilot immediately entered an autorotation. During the autorotation, the pilot relinquished the flight controls to the flight instructor, who elected to continue the autorotation to a field. The instructor added that during touchdown, the right front skid "sunk into the soft field," causing the helicopter's nose to drop. As the tail section rose, the main rotor blades severed the tail-boom, and the helicopter subsequently rolled onto its side.
The pilot stated that "they heard and then felt a vibration and a loud bang or explosion" that came from the aft section of the helicopter, prompting him to enter an autorotation.
Examination
A Federal Aviation Administration (FAA) inspector who responded to the site reported that the helicopter's main rotor blades severed the tail-boom during the landing. An examination of the helicopter was conducted by an FAA inspector and a technical representative from the airframe manufacturer. During the inspection, the engine was started and ran normally. The transmission rotated with oil visible in the sight gauge. The drive system's "V-belts" appeared undamaged and functional; the clutch actuator operated when electrical power was applied. The engine's lower coupling to the lower pulley driveshaft was intact, and the splined fittings were undamaged. The helicopter's cyclic and collective controls exhibited continuity through the range of motion. The main and tail rotor blades were examined; the tail rotor blades appeared undamaged, while the main rotor blades displayed various degrees of damage consistent with a sudden stoppage at low rotor RPM and blade impact with the tail-boom and ground.
The reason for the loud noise and vibration was not found.