Honeywell is to provide an all-new 7,500shp (5,600kW)-class turboshaft engine for the Sikorsky-Boeing Defiant X high-speed helicopter that the two prime contractors are pitching for the US Army’s Future Long-Range Assault Aircraft (FLRAA) competition.

Designated the HTS7500, the powerplant builds on the improvements being brought to the new -714C variant of the T55 engine for the Boeing CH-47 Chinook.


Source: Sikorsky-Boeing

That sees the T55 – which entered service in the early 1960s – gain a new compressor, helping to increase power by 20%, to around 6,000shp, and cut fuel burn by around 10%.

The HTS7500 uses the same compressor, but it is married to a new hot section offering a 25% power increase over the T55-714C, says Michael Madsen, chief executive of Honeywell Aerospace. Fuel burn will also see an “incremental” improvement, he says.

“It’s one of the largest programmes we have ever won at Honeywell and we are super-proud to be working with Boeing and Sikorsky. We are going to do our best to help them secure a win with the US Army,” says Madsen. 

Mark Cherry, vice-president and general manager of Boeing Vertical Lift, adds: “Honeywell’s history with Boeing and the US Army makes us even more confident that Defiant X is the best fit for the army’s total mission.”

Seeking to replace the Sikorsky UH-60 Black Hawk, the FLRAA contest pits the compound co-axial twin-engined Defiant X against the Bell V-280 tiltrotor, which will be powered by two Rolls-Royce AE 1107F turboshafts.

Whichever manufacturer wins will be in line for thousands of orders as the US Army – and potentially other services – replaces its Black Hawk fleet. A contract award is expected later this year.

The SB-1 Defiant demonstrator is powered by twin T55 engines.