Description

The Model 250 Series II turboshaft engines are of two-shaft modular design featuring four to six-stage axial and single-stage centrifugal compressors, a two-stage LP turbine, two-stage HP turbine with a hydromechanical fuel control system, and a gearbox with 6,000rpm output. Compressed air is routed to the aft end of the engine for combustion, with exhaust gases exiting upward from the middle of the engine. The larger Series IV family is identical in layout except for having one-stage centrifugal rather than a centrifugal/axial compressor. The latest Series IV turboshafts also feature a FADEC (Full Authority Digital Engine Control) system.

The highly successful family of Model 250 engines remains the industry-standard powerplant. More than 29,000 Model 250s have been delivered to date, with an estimated 15,000 engines currently in service. In 2005, the Model 250 celebrated the unprecedented milestone of 170 million flight hours, continuing to set new standards of operability and safety.

The long association of the Model 250 with unmanned aerial vehicle (UAV) applications was reinforced in February 2000 with the selection of the Northrop Grumman RQ-8A Fire Scout Vertical Take-off UAV (VTUAV) for a major US Navy/Marine Corps shipborne requirement. Based on the Model 250-C20W-powered Schweizer 330 helicopter, the Fire Scout is paving the way for a major new class of air systems. In addition to serving aboard the first flight of the U.S. Navy's Littoral Combat Ship (LCS), the Fire Scout VTUAV has also been selected to meet the U.S. Army's Class IV Future Combat Systems (FCS) UAV requirement.