Bell Helicopter lost the testbed aircraft for the transmission system of the company's new 525R Relentless in a crash on 7 August in Avalon, Texas.
The Bell 214ST (N409SB) had just completed a right turn when the flightcrew reported hearing a "bang", according to a preliminary report filed with the US National Transportation Safety Board. The chase aircraft informed the crew that "something had departed the tail of the helicopter", the NTSB says. The 214ST crew autorotated to land in a field nearby, but the helicopter "yawed and rolled right on landing". The flightcrew was not injured in the accident.
The Bell 214ST is used by the company for research and development flights. It was assigned to perform risk reduction tests for the transmission system on the Bell 525R, a super-medium twin.
Bell unveiled the 525R in February to challenge the AgustaWestland AW189 and Eurocopter EC175 in the super-medium segment. The 7-8t-class aircraft is expected to feature fly-by-wire controls leveraged from the Bell Boeing V-22 tiltrotor.
The 525R, powered by two General Electric CT7-2F1 turboshaft engines downrated to 1,800shp (1,300kW) each, will also become Bell's first five-bladed rotor system and first fully-articulated rotor head for a production aircraft.