Pratt & Whitney JT9D: the first high bypass ratio jet engine

Pratt & Whitney JT9D 

The JT9D program was launched in September 1965 and the first engine was tested in December 1966. It received its FAA certification in May 1969 and entered service in January 1970 on the Boeing 747. It subsequently powered the Boeing 767, Airbus A300 and Airbus A310, and McDonnell Douglas DC-10. The enhanced JT9D-7R4 was introduced in September 1982 and was approved for 180-minute ETOPS for twinjets in June 1985. By 2020, the JT9D had flown more than 169 million hours. Production ceased in 1990, to be replaced by the new PW4000.

The JT9D was developed from the STF200/JTF14 demonstrator engines. The JTF14 engine had been proposed for the C-5 Galaxy program but the production contract was awarded to the General Electric TF39. The engine’s first test run took place in a test rig at East Hartford, Connecticut, with the engine’s first flight in June 1968 mounted on a Boeing B-52E which served as a JT9D flying testbed. In 1968, its unit cost was $800,000.

Country: USA

First run: December 1966

Production: 3,500

Type: High bypass turbofan

Length: 3.37 m (132.7 in)

Diameter: 2.37 m (93.4 in)

Compressor: 3-stage low pressure 11-stage high pressure axial

Turbine: 2-stage high pressure 4-stage low pressure

Maximum thrust: 48,000 lbf (214 kN) takeoff

Overall pressure ratio: overall 26.7 (fan 1.67:1)

Bypass ratio: 4.8:1

Weight: 3,905 kg (8,608 lb)

Bourget Museum (ParisFrance)

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