Pratt & Whitney JT9D

File:P&W JT9D cutaway.jpg]]

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,{{cite web |publisher= Pratt & Whitney |title=JT9D |url=http://filecache.mediaroom.com/mr5mr_prattwhitney/180750/download/ce_jt9d_fact.pdf}} to be replaced by the new PW4000.

The JT9D was developed from the STF200/JTF14 demonstrator engines.The Engines of Pratt & Whitney: A Technical History, Jack Connors, {{ISBN|978 1 60086 711 8}}, p.409 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.The Engines of Pratt & Whitney: A Technical History, Jack Connors, {{ISBN|978 1 60086 711 8}}, p.412

In 1968, its unit cost was $800,000,[https://www.flightglobal.com/FlightPDFArchive/1968/1968%20-%200022.PDF Aero Engines 1968] Flight International 4 January 1968 ${{Inflation|US|0.8|1968|r=1}} million today.

The JT9D introduced advanced technologies in structures, aerodynamics, and materials, which included titanium alloys and nickel alloys, to improve fuel efficiency and reliability compared to the Pratt & Whitney JT3D earlier turbofan.

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 {{convert|8470|lb|abbr=on}} and produced {{convert|43500|lbf|abbr=on|kN|lk=}} thrust.The Engines of Pratt & Whitney A Technical History, Jack Connors, {{ISBN|978 1 60086 711 8}}, Table 3

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 resulting in rubbing of high-pressure turbine blade tips. This was solved by strengthening the engine casing and adding yoke-shaped thrust links.Flight International, 13 November 1969, p.749

JT9D engines powering USAF Boeing E-4A airborne command posts were designated F105.

In 1973, NAVSEA selected the JT9D-70 for use as a high efficiency gas turbine in the 30,000 hp to 50,000 hp class, installing its compressor into the pre-existing FT4 marine gas turbine to create the FT9. The engine had been recommended for provisional acceptance in June 1980, with full acceptance pending for ship-specific installation. The engine was selected by the Navy for use in Rohr Marine's 3,000 ton Surface Effect Ship, and one was to be installed aboard the vessel GTS Asiafreighter.Groghan, D. A., Miller, C. L (1981). [http://asmedigitalcollection.asme.org/GT/proceedings-pdf/GT1981/79610/V001T02A006/2393326/v001t02a006-81-gt-197.pdf Development of FT9 Marine Gas Turbine] (PDF). Paper Number 81-GT-197. The American Society of Mechanical Engineers.{{Cite journal |last=Fairbanks |first=John W. |date=December 1975 |title=The FT9 Marine Gas Turbine Engine Development Program |journal=Naval Engineers Journal |pages=79-96}}

All variants have the same number of compressor and turbine stages.

{{notelist}}

• Airbus A300
• Airbus A310
• Boeing 747-100/200/300/SP
• Boeing 767 (early models)
• Boeing RC-1
• McDonnell Douglas DC-10-40

{{jetspecs

|ref=Pratt & Whitney

|type=High bypass turbofan

|length={{cvt|132.7|in|m}} (flange to flange)

|diameter={{cvt|93.4|in|m}} (fan tip)

|weight={{cvt|8608|lb|kg}}

|compressor= 3-stage low pressure 11-stage high pressure axial

|combustion=

|turbine= 2-stage high pressure 4-stage low pressure

|fueltype=

|oilsystem=

|power=

|thrust={{cvt|48,000-56,000|lbf|kN|0}} takeoff (flat rated at {{cvt|86|°F|°C}}) Note: the thrust range applies to various -7R4 variants for different aircraft.

|compression=overall 26.7 (fan 1.67:1)

|bypass=4.8:1

|aircon=

|turbinetemp=

|fuelcon=

|specfuelcon

|power/weight=

|thrust/weight=

}}

{{Aircontent

|related=

• Pratt & Whitney PW4000

|similar engines=

• General Electric CF6
• General Electric TF39
• Progress D-18T
• Rolls-Royce RB211

|lists=

• List of aircraft engines

|see also=

}}

{{Reflist}}

{{Commons category}}

• {{official website|https://www.pw.utc.com/products-and-services/products/commercial-engines/jt9d}}

{{P&W gas turbine engines}}

{{USAF gas turbine engines}}

{{DEFAULTSORT:Pratt and Whitney JT9D}}

Category:High-bypass turbofan engines

JT9D

Category:1960s turbofan engines