Pratt & Whitney JT9D


The Pratt & Whitney JT9D engine was the first high bypass ratio jet engine to power a wide-body airliner. Its initial application was the Boeing 747-100, the original "Jumbo Jet". It was Pratt & Whitney's first high-bypass-ratio turbofan.

Development

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 A310, and 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 has flown more than 169 million total hours.
Production ceased in 1990, to be replaced by the upgraded PW4000.
The JT9D was developed as part of the design of the C-5 Galaxy. A contract was awarded to Pratt & Whitney to study the type of large engine needed, but the production contract was eventually 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 747 testbed.

Design

Advanced technologies in structures, aerodynamics, and materials improve fuel efficiency and reliability.
The JT9D was built using titanium alloys and nickel alloys. The engine featured a single-stage fan, a three-stage low-pressure compressor, and an eleven-stage high-pressure compressor coupled to a two-stage high-pressure turbine and four-stage low-pressure turbine. The JT9D-3, the earliest certified version of the engine, weighed and produced thrust.
Pratt & Whitney faced difficulties with the JT9D design during the Boeing 747 test program. Engine failures during the flight test program resulted in thirty aircraft being parked outside the factory with concrete blocks hanging from the pylons, awaiting redesigned engines.
Boeing and Pratt & Whitney worked together in 1969 to solve the problem. The trouble was traced to ovalization, in which stresses during takeoff caused the engine casing to deform into an oval shape and cause the high-pressure turbine blades to grind against the sides. This was solved by strengthening the engine casing and adding yoke-shaped thrust links.
JT9D engines powering USAF Boeing E-4A airborne command posts were designated F105.

Variants

All variants are dual axial turbofans with annular combustion chambers and 6 turbine stages.
ModelCertificationTakeoff, dryLengthWidthWeight rpm rpmFanApplication
15-stageJT9D-3AJan 9, 197036507850B747
15-stageJT9D-7Jun 14, 197137508000B747
15-stageJT9D-7ASep 22, 197237508000B747
15-stageJT9D-20Oct 16, 197236508000DC-10
15-stageJT9D-7HJun 19, 197436508000B747
15-stageJT9D-7AHJun 19, 197436508000B747
15-stageJT9D-7FSep 30, 197437508000B747
15-stageJT9D-7JAug 31, 197637508000B747
15-stageJT9D-20JDec 29, 198637508000DC-10
16-stageJT9D-59ADec 12, 197437808011DC-10 A300
16-stageJT9D-70ADec 12, 197437808011B747
16-stageJT9D-7QOct 31, 197838888000B747
16-stageJT9D-7Q3Oct 22, 197939608000B747
16-stageJT9D-7R4DNov 25, 198037708000B767
16-stageJT9D-7R4D1Apr 1, 198138108000A310
16-stageJT9D-7R4EApr 1, 198137708000B767
16-stageJT9D-7R4E1Apr 1, 198138108000A310
16-stageJT9D-7R4G2Jul 23, 198238258080B747
16-stageJT9D-7R4H1Jul 23, 198238108080A300-600
16-stageJT9D-7R4E4Mar 29, 198538108080B767

Applications