[Corrected: Contrary to our first report, Honeywell pulled the T55-715 from consideration for the CH-53K engine contract.]

The "great engine war" is making an unlikely resurgence. Within the past few months, Pratt & Whitney's F100 has shut out the General Electric F110 for a string of new foreign sales for BoeingF-15sand Lockheed Martin F-16s.

In recent years, GE came to dominate new orders in the fighter engine competition that dates to the early 1980s, when congressional pressure forced the US Air Force to develop the upstart F110 as an alternative to the F100.

Moreover, the competition to power the Lockheed F-35 Joint Strike Fighter continues to overshadow the original engine war. Indeed, saving the GE/Rolls-Royce F136 from programmatic extinction has become an expected yearly drama.

 © Pratt & Whitney
First flight of the F-35B STOVL variant of the JSF gave P&W's F135 a vote of confidence

The US Congress continues to fight to save the alternate engine programme from the US Department of Defense's repeated attempts to kill it. Meanwhile, P&W continues to develop the F135 originally selected by Lockheed to power the F-35.

If anything, P&W's competitive resurgence this year on the foreign market with an enhanced version of the F100 may offer a new counter-point to critics of sustaining a healthy and long-term engine competition.

In 2004, P&W received USAF funding to leverage F119 technology for the F100 family. The company realised the F100 needed a boost to remain competitive against an upgraded version of GE's F110, after the latter began to dominate the export market.

The fruit of that competitive pressure is the F100-229 enhanced engine package (EEP). The EEP is initially aimed at new engine sales to foreign customers, but P&W intends to market the product for new engine and retrofit orders by the US military as well.

Improving Reliability

The EEP focuses primarily on improving reliability through adding a real-time health monitoring system and an upgraded digital electronic engine control system. Time between overhaul should rise from 4,300 cycles to 6,000 cycles. Engine thrust also grows slightly from 29,000lb (130kN) to 29,100lb.

The South Korean air force endorsed P&W's strategy earlier this year by ordering the engine to power a new batch of F-15Ks, even though F110s powered the first batch.

More recently, the Royal Moroccan Air Force selected P&W's improved F100 EEP to propel its new fleet of F-16 Block 52s. Deliveries for the $170 million order are scheduled in 2010 and 2011. Saudi Arabia and another undisclosed foreign customer have also purchased the P&W EEP as a retrofit.

Meanwhile, GE continues to sell F110s on the export market. A total of 58 F110-129C engines have been sold to power Boeing F-15s purchased by the Royal Saudi Air Force. Another 48 engines are now installed on Singapore's nascent F-15SG fleet. Both air forces purchased the engine in the service life extension programme (SLEP) configuration.

But the USAF's ongoing SLEP to upgrade more than 800 of all 2,700 F110s sold by the manufacturer remains the mainstay of GE's production activity.

More than 600 F110-100s and more than 200 F110-129s are being upgraded to the SLEP standard. The improvements will allow a fraction of the F-16 and F-15 fleets to remain in service through 2025.

The SLEP redesigns the flowpath and core engine parts, inserting a new core derived from the CFM56-7. Other features include a new high-pressure compressor rotor, high-pressure turbine rotor, combustor and nozzles.

F136-JSF engine 
 © Rolls-Royce
The F136 remains in development as a JSF alternative despite the threat of cancellation

A termination threat still hangs over the F136, but both manufacturers continue to make progress on their designs.

P&W's F135 earlier this month received a huge vote of confidence with the first flight of the F-35B short take-off and vertical landing variant.

Although the flight only tested the aircraft's conventional mode, the event helped alleviate concerns about a nagging turbine blade fatigue problem. Despite engine test failure caused by the blade problem earlier this year, the first F-35B - named BF-1 - flew on 11 June, only 19 days late.

First flight followed a string of major events for the STOVL F135-600 variant. On 25 May, P&W completed ground tests demonstrating conversions from horizontal to vertical flight. Eleven days earlier, the F-35 joint programme office certificated the STOVL variant for flight operations.

In all, the F135 engine has amassed nearly 10,000 test hours during the system development and demonstration phase. The conventional take-off and landing engine variant has compiled 43 flights and more than 51 flight test hours to date.

The GE/Rolls-Royce fighter engine team is also making progress with the F136, which is nearing its fourth year in development. Full-up STOVL mode tests are due to begin shortly, but engineers have already activated the lift fan and roll-posts. The F136 also recently cleared windtunnel tests examining performance at high altitude with afterburner engaged.

GE's F414 continues to pace new military engine sales thanks to the US Navy's continued annual purchases of F/A-18E/F Super Hornets and now the EA-18G Growler. The USN delivered the first operational EA-18G to NAS Whidbey Island, Washington, on 3 June. GE will eventually deliver 1,164 installed engines to the USN through 2014 to support F/A-18E/F purchases, with more than 800 delivered already.

Another recent first for the F414 family was the maiden flight in late May for the single-engine Saab Gripen Demo programme. The demonstrator is powered by one of two F414Gs delivered by GE to support Saab's programme.

Australian Order

Efforts to sell more F414s and growth versions of the F404 powering the current Gripen have gained new traction. Australia's decision to buy 24 F/A-18Fs adds 48 F414s to the orderbook. Meanwhile, GE has completed deliveries of 17 F404-IN20 engines to Hindustan Aeronautics to power the Tejas light combat aircraft. Another 24 are on contract by HAL through 2010.

The F404-102 has been deployed with the first Korea Aerospace Industries/LockheedT-50s to enter service with full mission capability. GE has delivered 44 engines to South Korea and 52 more are on contract.

Meanwhile, P&W is moving forward on developing the next major military derivative of a civil aircraft engine. The USAF awarded a P&W/Seven Q Seven joint venture a $210 million contract to adapt the JT8D-219 turbofan to re-engine the fleet of Northrop Grumman E-8C JSTARS ground surveillance aircraft. Production is to begin in 2010.

The goal of the programme is reduce the E-8C's fuel burn by 20% compared to its current TF33 engines.

Honeywell's top-seller - the T55-GA-714A engine - continues to advance in production with further sales of the Boeing CH-47 Chinook helicopter. Prospects for more sales are dominated by a disputed contract award for up to 146 helicopters. The USAF is again recompeting the combat search and rescue (CSAR-X) contract. The HH-47 Chinook has already been selected twice, but both decisions have been overturned. A final decision could be revealed in late 2008, barring further appeals.

Honeywell Buoyed

As the CSAR-X process unfolds, Honeywell's production line remains buoyed by the US Army's long-term plan to buy hundreds of upgraded CH-47Fs. Honeywell shipped 203 T55 engines to the army in 2007 alone, including one engine that was shipped early.

 © Pratt & Whitney
P&W has a $210 million contract to adapt the JT8D-219 to re-engine E-8C JSATRS aircraft

A 22% more powerful variant - the T55-715 - has been looking for customers since Honeywell decided to not offer it in the competition for the US Marine Corps Sikorsky CH-53K. Boeing has publicly discussed growth versions of the CH-47, but those plans so far do not require an engine upgrade.

Honeywell, meanwhile, is ramping up production for its line of small engines after a long hiatus. The first resurgence of Honeywell's small turboshaft programme overcame a crisis within the past 12 months. The single-engined Bell Helicopter ARH-70 Arapaho was threatened with cancellation in 2006 after repeated cost overruns and flight-test mishaps.

The army accepted Bell's recovery strategy and the programme reportedly remains on track. Honeywell delivered two HTS900-2s to Bell in 2007, but a backlog of more than 500 orders for the ARH-70 awaits.

The army introduced the ARH-70 after cancelling the Sikorsky/Boeing RAH-66 Comanche helicopter in 2003. The engine developed for that programme - the LHTEC CTS800-4 - is now sold on the export market by the Honeywell/R-R joint venture.

In early May, LHTEC announced delivering the first CTS800-4 to AgustaWestland for the Future Lynx helicopter. Overall, LHTEC has combined orders totalling 384 for the CTS800-4 for the Future Lynx, Turkey's T129 attack helicopter and the Japanese ShinMaywa US-2 amphibian.

Honeywell has combined with another competitor to develop a next-generation engine to power medium-lift helicopters, such as the Sikorsky UH-60 Black Hawk. Advanced Turbine Engine (ATEC), a Honeywell and P&W joint venture formed in 2007, announced a $108 million contract award in early May.

The US Army selected ATEC for the advanced affordable turbine engine technology demonstrator programme.The goal of the project is to validate technologies that can provide a 65% improvement in shaft horsepower to weight ratio and a 25% increase in specific fuel consumption for a 3,000shp (2,240kw) engine.

If ATEC's HPW3000 is successful, the company will develop a serious challenge to GE's grip on the markets for UH-60- and Boeing AH-64-class transport and attack helicopters.

Not willing to leave the market without a fight, GE is responding with its own next-generation T700 design called the GE3000. The army also awarded an almost identical contract to GE to start work on a new engine that can deliver the same performance improvements over the T700.

The new powerplant could be used to support a retrofit programme for the Black Hawk and Apache fleets at the end of the next decade. Additionally, the army has notional plans to introduce a joint multirole replacement aircraft after 2020.

Despite the beginnings of a replacement programme, the T700 continues to be the highest-selling military engine, finding new customers in the past decade with the Lockheed VH-71A, the Sikorsky UH-60M and even a rear-drive replacement for an indigenous South Korean helicopter.


For the latter, GE has started production of the YT706 turboshaft after completing development ground and flight tests last year. The YT706 is a growth version of the CT7-8, and GE won a competition in 2005 to supply 120 engines to the US special forces. Compared with the -701D, the YT706 has a 25% larger compressor, full-authority digital engine control and improved turbine cooling.

Competition may again be heating up in the heavylift turboshaft market, driven as much by concerns about the longevity of the R-R AE1107C engine as by the new entrance of a high-powered competitor.

In 2006, Sikorsky selected the GE38-1B to power the 80,000lb-class CH-53K heavylift helicopter. The 7,000shp GE38 is based on the T407 turboprop that powered the ill-fated Lockheed P-7 maritime patrol aircraft and the GE27 technology demonstrator. After the P-7 was cancelled in the early 1990s, GE adapted the core into the GE/Honeywell CFE738 business jet turbofan.

The GE38 is designed to provide 57% more power and 18% higher specific fuel consumption than the GE T64 powering the CH-53E. GE was scheduled to begin rig tests for the GE38-1B this year in advance of a first engine run in 2010 and flight tests in 2011.

The USMC is looking at the GE38-1B to replace the Bell Boeing MV-22 Osprey's AE1107Cs. As far back as 2004, Sikorsky officials discussed the option of transferring theCH-53K engine to the V-22 pro­­gram­me to offer the USMC a common heavylift engine. New concerns about the AE1107Cs due to corrosion on compressor blades have driven the USMC to reconsider Sikorsky's original proposal.

The GE38 has more rugged aerofoil leading edges to increase durability. Compressor aerofoils, moreover, are coated to protect from corrosion with the T64. GE is also reducing parts count on the GE38 by 60%, using mainly blisks in the compressor and boltless rotors.

EADS North America plans to introduce the Airbus Military A400M in the US market, and that may offer a new application for converted, heavylift turboshaft engines. The A400M is powered by the Europrop International TP400-D6, but EADS may decide it needs to offer a North American-based engine alternative. Options include an uprated GE38 or the Pratt & Whitney Canada PW800.

Source: Flight International