Williams FJ44

The Williams FJ44 is a family of small, two-spool, turbofan engines produced by Williams International/Rolls-Royce for the light business jet market. Until the recent boom in the very light jet market, the FJ44 was one of the smallest turbofans available for civilian applications. Although basically a Williams design, Rolls-Royce was brought into the project, at an early stage, to design, develop and manufacture an air-cooled high-pressure (HP) turbine for the engine. The FJ44 first flew on July 12, 1988 on the Scaled Composites/Beechcraft Triumph aircraft.

FJ44
A Williams FJ44-3ATW turbofan engine
Type	Turbofan
National origin	United States
Manufacturer	Williams International
First run	1985[1]
Major applications	Beechcraft Premier I Cessna CitationJet Piper PiperJet Altaire Saab 105 Grob G180 SPn
Developed into	Williams FJ33

The Williams FJ33 is a smaller engine based on the basic FJ44 design.

Production started in 1992 with the 1,900 lbf (8.5 kN) thrust FJ44-1A, which comprises a 20.9 in (530 mm) diameter single stage blisk fan plus a single intermediate pressure (IP) booster stage, driven by a 2 stage low pressure (LP) turbine, supercharging a single stage centrifugal high pressure (HP) compressor, driven by a single stage uncooled high pressure (HP) turbine. The combustor is an impingement cooled annular design. Fuel is delivered to the combustor through an unusual rotating fuel nozzle system, rather than the standard fuel-air mixers or vapourisers. The bypass duct runs the full length the engine. Specific fuel consumption at 1900 lbf (8.45 kN) thrust at SLS, ISA is understood to be 0.456 lb/(hr lbf). A derated version, the 1,500 lbf (6.7 kN) thrust FJ44-1C has an SFC of 0.460 lb/lbf/h (46.9 kg/kN/h).^[2][3]

An uprated version, the 2,300 lbf (10 kN) thrust FJ44-2A, was introduced in 1997. It has a larger 21.7 in (550 mm) diameter fan, with two additional booster stages to increase core flow. Owing to stressing considerations, the centrifugal compressor is throttled-back aerodynamically to a lower HPC pressure ratio than the -1. Other features include an exhaust mixer and an electronic fuel control unit.^[4] The 2,400 lbf (11 kN) thrust FJ44-2C is similar to the -2A, but incorporates an integrated hydromechanical fuel control unit.

Further updates include the 2004 introduction of the 2,820 lbf (12.5 kN) thrust FJ44-3A, which is similar to the -2A, but features an increased diameter fan and dual channel FADEC (Full Authority Digital Engine Control) unit.^[5] The 2,490 lbf (11.1 kN) thrust FJ44-3A-24 is a derated version of the -3A.

In 2005, a new low end version, the FJ44-1AP, was introduced, with a 1,965 lbf (8.74 kN) takeoff thrust, 5% better specific fuel consumption, and lower internal temperatures. The -1AP is similar to the -1A, except for a higher pressure ratio fan, a new combustor and LP turbine, a new full length bypass duct/exhaust mixer and a dual channel FADEC.^[6]

Released in 2007 was the new 3,600 lbf (16 kN) thrust FJ44-4, which has a hi-tech fan of larger diameter than the -3 unit.^[7] As of March 2010, this engine was only in use on the Cessna CJ4, and since 2018 also on the new Pilatus PC-24.

FJ44-1A

FJ44-1AP

FJ44-1C

FJ44-2A

FJ44-2C

FJ44-3A

FJ44-3AP

FJ44-4A

FJ44-4M

F129

Military designation for a derated FJ44 with 1500lbf (6.672kN) power output.

Related development

• Williams FJ33

Related lists

• List of aircraft engines

• Williams International product page