INFO AÉRO QUÉBEC – AIAC CAS 2016: The Pratt & Whitney F135: The Only Fifth Generation Military Turbofan in Production.

 

OTTAWA, ONTARIO – On November the 16^th, at the closing of the 2016 Canadian Aerospace Summit organized by the Aerospace Industries Association in Canada (AIAC), Info Aéro Québec met Clifford R. Stone, Vice President, International Programs & Business Development, Pratt & Whitney at Hartford, Connecticut to discuss about the F135 military jet engine.

The Pratt & Whitney F135 propulsion system powers the F-35 Lightning II, fifth generation advanced, single-engine, tactical fighter developed by Lockheed Martin in conjunction with BAE Systems and Northrop Grumman.

The Pratt & Whitney F135 family has several distinct variants (F135-PW-100, -400 and -600), including a conventional, forward thrust variant and a multi-cycle SVTOL (Short/Vertical Take-Off and Landing) variant that includes a forward lift fan. The F-135, a mixed-flow afterburning turbofan, was derived from the F119 engine which powers the twin-engine fighter Lockheed Martin F-22A Raptor but was given a new fan and low pressure turbine optimized for the Joint Strike Fighter (JSF) Lockheed Martin F-35 Lightning II. ‘The F-35 engine is a growth version of the F-22 engine’ said Mr. Stone, ‘Our second fifth-generation military engine’.

The F135 is built in a Pratt & Whitney facility in Connecticut and for international partners in a recently opened plant in West Palm Beach, Florida.

The F135-PW-100 which powers the F-35A has length of 220 inches (559 cm), a maximum diameter of 46 inches (117 cm)  and 43 inches (109 cm) at the fan inlet and a dry weight of 3,750 lb (1,701 kg). Composed of a 3-stage fan, 6-stage high-pressure compressor, an annular combustor, a 1-stage high-pressure turbine and a 1-stage low-pressure turbine, the F135 has a maximum thrust of 43,000 lbf (190 kN) and offers a thrust to weight ratio of 7.47:1 dry and 11.467:1 with afterburner.

The engine for the land-based conventional take-off and landing (CTOL) F-35A and the carrier-based short take-off and landing (STOL) F-35C is exactly the same. The short and vertical take-off and landing (SVTOL) F-35B uses the same engine as the A and B but is added a Rolls Royce engineered, designed and built lift system which includes a lift fan and nozzles. All engines are sharing the same part numbers.

The Joint Strike Fighter (JSF) program was designed to replace the F-16 Falcon and F-18A/B/C/D Hornet tactical fighters and A-10 Thunderbird II and AV-8B Harrier attack aircraft. To keep development, production, and operating costs down, a common design was planned in three variants that share 80 percent of their parts.

McDonnell Douglas, Northrop Grumman, Lockheed Martin and Boeing made submissions to the US department of Defense.

On November 16, 1996, two contracts to develop prototypes were awarded, one each to Lockheed Martin for its X-35 and Boeing for its X-32. Each firm produced two aircraft to demonstrate conventional takeoff and landing (CTOL), carrier takeoff and landing (CV version), and short takeoff and vertical landing (STOVL).

During concept definition, two Lockheed Martin airplanes were flight-tested: the X-35A which was later converted into the X-35B and the larger-winged X-35C.

The contract for System Development and Demonstration (SDD) was awarded on 26 October 2001 to Lockheed Martin whose X-35 beat the Boeing X-32.

The F-35 first flight occurred on December, the 15^th, 2006 while the first F-35A AF-1 rolled out on December, the 19^th, 2008

The current F-35 order book stands at 3105 aircraft:

USAF 1763 F-35A

USN USMC 680 F-35B/C

UK Royal Navy 138 F-35B

Italy 60 F-35A 30 F-35B

Netherlands 37 F-35A

Turkey 100 F-35A

Australia 100 F-35A

Norway 52 F-35a

Denmark 30 F-35A

Israel 33 F-35A

Japan 42 F-35A

South Korea 40 F-35A.

Reminding that the development of the F-35 is done, Mr. Stone underlined that ‘we are starting the STDD program. In July of this year it was complete pencil down no more design’. All 38 000 spec points except six are now closed in the design’.

Some 307 engines have been already delivered to date including 285 production engines to eight services in eleven locations ‘We are delivering in lot 8 and we are under contract for lot 9 and lot 10’.

Pratt & Whitney is ramping up F135 production after a few years of flat output at 50 engines a year. This year, 65 F135 will delivered, 84 next year and about 100 in 2020.

Typically, 1.15 engine is built for each aircraft delivered.

Already more than 200 F-35 has been delivered, all based in Continental USA. In four years, 650 F-35 will be flying and about 1200 in 2024.

Affordability.

Since 2009, according to Mr. Stone, the overall cost for the F135 has been reduced by half. At the time, Pratt & Whitney promised that by engine 300, the unit cost will be the same than the one of an F-22 engine even if the F-135 has 5000lb more thrust.

As anticipated, Pratt &Whitney has reduced the price for engines in every low-rate initial production (LRIP) lot:

LRIP 2: -15,8%

LRIP 3: -6,5%

LRIP 4: -13,3%

LRIP 5: -3,1%

LRIP 6: -2,3%

LRIP 7: -4,2%

LRIP 8: -3,3%

LRIP 9-10: -3,4%

Increased annual engine production will bring additional per unit cost reduction benefit. It has been evaluated that for every 10-engine increase in yearly volume, the unit price of each engine decrease by at least $60 000.

Performance

According to Clifford R. Stone, F135 mission availability rate goal is 95% and current production engines are already exceeding key 2020 reliability requirements of more than 90%.

Since December 2006, F135 has already accumulated more than 60 000 flight hours and has a near flawless performance during recent developmental and operational testing from the USS Wasp, USS Nimitz and USS Eisenhower sea trials that need little or no unscheduled engine maintenance.

Pratt & Whitney met the US Marine Corps initial operational capability (IOC) objective and is on track to meet its commitment for US Air Force IOC.

The Hartford-based engine manufacturer is working with the F-35 Joint Program Office and Lockheed Martin to ensure an ALIS 2.0.2 release with propulsion that will not impact airworthiness, aircraft engine availability, or spare parts management.

Pratt & Whitney is combining lessons learned from sustaining the F100 powering the F-16 and F-15, F117, the C-17 and F119, the F-22A engine programs to provide the highest level of availability, affordability, and safety to the customers.

In the past four years, Pratt & Whitney achieved 100% on-time delivery and reduced all supplier quality escapes by 80%. The engine manufacturer is sourcing key engine components to more than one supplier to mitigate risk.

In fact, to be sure to meet the production need, Pratt & Whitney relies on dual source for 95% of the engine parts in order ‘not to have a single point of failure’.

Growth and maturity

Thanks to investment from Pratt & Whitney and the US government into S&T, demonstration programs apply directly to the F135 and can enhance the capabilities and relevance of the F135 for decades to come. These technologies will be integrated into F135 production engines in 2020.

Through an AFLR sponsored program, Pratt & Whitney demonstrated with success the highest ever turbine temps in production-based engine under XTE68/LFI engine demonstration.

Through a US Navy-sponsored program, Pratt & Whitney identified growth options increasing thrust up to 10%, better durability and a 7% improvement in fuel burn for the F-35.

Canadian participation in the F135.

Economic benefits are a big part of the Joint Strike Fighter program since its inception.

‘We found there are some great luck in Canada’ said Clifford Stone, ‘in spite of the fact that is hard to make engines part because of metal tight tolerance’.

Pratt & Whitney Canada along with more than 70 other Canadian companies are supplying high technology parts and software on the F-35 line today. Among them:

British Colombia:

Xantrex Technology:     Test equipment

Manitoba:

Magellan Bristol:           VAVBN and Flit fan supports

Ontario:

Magellan Haley:            Gearbox casting

Magellan Orenda:                   Fan sync ring – Non-recurring engineering

Mxi:                            Maintenance software

Casebank:                     Off board PHM

FAG Aerospace:            Tower shaft bearings

#4 and #5 bearings

Lift fan bearings

Gastops:                       Oil debris monitor (ODM)

Lift fan ODM Sensors

F135 fan eddy current sensor

MDS Aero: lift fan mover

Kenmetal Stellite:                  Turbines tubes and covers

Québec:

Montreal Carbide:         Powder metal

Mindready Solutions:     Test equipment

Pratt & Whitney Canada:5^th stage integrally bladed rotor

Material Characterization

4^th stage IBR

While others 4^th generation fighter programs are at the end of their production run, the F-35 production had just started and will result in over 3000 aircraft being manufactured, sustaining jobs for more than 20 years from now.

As mentioned by Mr. Stone, for the time being F-35 Foreign Military Sales (FMS) are running until 2059 and production figures are revised every six months.

It is fair to remind that the F-35 will replace the F-16 which 4573 has been built, the F-18A/B/C/D, 1480, the A-10, 716 and the AV-8B, 337.

Engine performance.

The F-35 engine has met more than 99% of its design specifications, including more than 26000 component level requirements and is exceeding key 2020 reliability requirements including engine mission availability after more than 60 000 flight hours.

The US Marine Corps has declared F-35B initial operational capability (OIC) in July 2015 and the USAF, the F-35A in August 2016.

Maturity

Single engine durability, reliability and safety is a result of decades of knowledge and experience gained from the dual engine airframe which has been applied to single engine designs the dual engine. It has been the case with the Pratt & Whitney F100 turbofan powering the twin engine F-15 Eagle and the single engine F-16 Falcon.  Now, the same process is happening with the F119 on the twin engine F-22 Raptor and on the single engine F-35 Lightning II.

The F135 is a derivative of the F119, the F-22A Raptor engine which has been in service for more than 10 years and flew more than 250 000 successful combat missions.

The F-35 engine incorporates the lessons learned on the F100 which flown over three million flight hours in the single engine F-16 and an industry best record in reliability for more than 30 years.

Redundancy durability

Each of the F135 two engine electronic controls have two identical motherboards. If any essential mechanical control, pump or actuactor fails, the backup automatically kicks in.

During testing, the F135 engine continued to operate without oil in flight for eight minutes.

The F135 can operate for more than seven years or 1200 missions without planned maintenance.

Foreign Object Debris

The F-35 engine predecessor, the F119 ingested ‘a twelve pound bird similar to a Canadian geese’ said Mr. Stone and brought back the pilot safely who did not even know what happened. F-35 pilots have landed safely with a functioning engine after more than 70 ingestion events including bird strikes.

According to Pratt & Whitney literature, the F-35 engine is the first ever equipped with a system that records anything that enters or exits the engine. If the damage warrants it, the pilot is warned in flight but for routine events, the maintenance personnel are alerted back on the ground.

The design of the F135 engine is foreign object debris (FOD) tolerant. Clifford Stone reminded that the F135 as well as the F119 fan blades are very wide, short, thick and robust that give them a lot of FOD and bird ingestion tolerance.  It is more bird resistant than any fourth-generation engine like the F404 powering the F-18E/F according to Mr. Stone.

Extreme artic weather conditions

In climatic icing tests at USAF McKinley Climatic Laboratory located at Eglin AFB in Florida, the F-35 engine demonstrated perfect operation in all icing conditions.

The effectiveness of the propulsion ice protection system was tested under simulated flight conditions at -22F, -13F, -10F, 14F and 24F with pre and post-flight inspections conducted at all temperatures.

The propulsion anti-ice system is fully integrated and can be activated either by an inlet-mounted sensor or manually by the pilot.

Sustainment.

Regional warehouses located in North America, Europe and Asia/Pacific    are required to perform the aircraft and the engine maintenance.

Concerning the F135 engine, Mr. Stone said that three depots are planned in North America, three in Europe and two in Asia-Pacific. For now, in North America, one is located at Tinker AFB, Oklahoma and another one at NAS Jacksonville in Florida.  The location of the third one is to be determined and Canada has expressed interest. Like in the case of Tinker AFB and NAS Jacksonville, this facility would have to be located on a military facility in the case of Canada, a Canadian Force Base, where the maintenance will be performed by military personnel while the facility will be managed by Pratt & Whitney.

 

 

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