Pratt & Whitney Les nouveaux GTF "Purepower"

CFM VERSUS PRATT & WHITNEY
Point/counterpoint On the reduced part count in Pratt & Whitney geared turbofan low-pressure sections
CFM Says that in a shop visit for the CFM56, 93% of the cost comes from the core and forward section of the low-pressure turbine. It says P&W has fewer parts in the booster (low-pressure compressor) and back stage of the LPT, but those areas are less than 7% of the maintenance costs.
P&W Maintains that replacing nickel super alloy (blade material in the LPT) with steel for the gear system makes for an inherently lower-cost engine to make and maintain, with fewer exotic materials.
Point/counterpoint On hot section temperature
P&W The company believes its rival's Leap X has a 100-150e_SDgrF (37.7-65.5°) hotter turbine inlet temperature and 10-15.5e_SDgrC hotter compressor exit temperature, which it says will probably have a substantial impact on [part] life.
CFM Says maintenance costs are related to the metal temperature, not the air temperature. CFM says it has designed the Leap X HPT blades to operate at the same temperature as CFM56 blades.
Point/counterpoint On having a gearbox with respect to maintenance
CFM Warns that there is a 5-10% increase in maintenance costs in its GE turboprop business because of the gearbox.
P&W Is telling customers they will not have to do anything to the gearbox for 40,000h, which is two overhaul cycles. Says it has not been successful in getting the gears to wear in testing to date.

As expected, the marketing and rhetoric surrounding the favoured dual-spool turbofan engine for the re-engined and next generation single-aisle commercial aircraft heated up along with the temperatures at Farnborough.
CFM International took the first jab at its pre-show press conference, where CFM executive vice-president Chaker Chahrour discussed benefits of a slow-turning low-pressure turbine (LPT), a design necessity for the company's Leap-X 30,000lb thrust (133kN) class turbofan design, the engine of choice for the Comac C919. "Keep the LPT running slow," says Chahrour. "You speed up the LPT, you pay the costs."
Pratt & Whitney's geared turbofan has a low pressure spool [LPT and low pressure compressor (LPC)] that, by design, spins more than twice as fast as the CFM design - about 8,500RPM. Because it can spin faster, the low pressure spool for the Bombardier CSeries engine requires only three stages.
The CSeries is one of three airframer wins for the GTF so far. A 3:1 gearing system between the low pressure spool and the fan slows the fan to an optimum speed at just below Mach 1, says Pratt. Though the gearing system weighs 113-136kg (250-300lb), Saia says it saves up to 320kg per engine when considering fewer low pressure spool stages needed, a net gain of as much as 182kg.
P&W vice-president, next-generation product family, Bob Saia says the engine maker has a large knowledge base with such speeds - the Pratt & Whitney JT8D turbojet that powers aircraft like the Boeing 727 and Boeing 737-100/200. Note that Boeing selected CFM as the sole supplier of the 737 engines starting with the 737-300. CFM is designing a low pressure spool that turns at "just over" Mach 1, a number P&W disputes. "The physics won't allow it," says Saia.
Both manufacturers are scouring their engines for weight savings to counter the increase that naturally comes with the larger 18-blade fans and associated support structure. CFM estimates it is saving 450kg per engine through its new resin transfer mould (RTM) composite fan blades, each of which is protected by a titanium leading edge. Endurance testing of the blades is about to start, following a battery of tests including bird strike.
CFM plans to have the design freeze of its Leap X1C engine and fan for the C919 in 2011 and first engine to test (FETT) in late 2012 followed by certification in 2013.
P&W looked at composite blades but has decided on a bi-metallic blade, the exact details of which have not been revealed. "We found it had the same weight as composite but has the significant benefit of making the blade thinner," says Saia. "It has better [aerodynamics] and still meets bird ingestion requirements." Saia says bird ingestion and blade-out tests are complete and the first set of 18 fan blades are complete. P&W will begin building up its 24,000lb-thrust PW1524G engine for the CSeries in August, targeting a third quarter 2012 certification, about one year ahead of the Leap X.
Although there low speed spools differ, both companies have similar high pressure, or hot section designs, which CFM says historically accounts for 90% of the maintenance costs.
P&W says its design will provide a more than 20% reduction in maintenance costs compared with today's CFM56, a number it calculates to be $750,000 per aircraft per year.
Saia says the savings comes from having six fewer low spool stages and a cooler running core, a less thermally efficient option, but one that is counterbalanced by longer part life.
"There is scepticism, because it's a big number," says David Hess, president of P&W. "As we take them through that data, the scepticism kind of goes away. We show them everything that is coming out. We've convinced them, I think we've convinced Airbus and convinced Embraer and others that the number is real."
Both companies say they continue to work with Boeing and Airbus on designs for a potential re-engined 737 and A320. Trade studies include elliptical nacelles that could allow the larger fans to fit on both aircraft, particularly the lower-sitting 737. Saia says both CFM and P&W would have to offer a smaller fan size for the 737, noting CFM's smaller offering for the 737 versus the A320 today. Regardless, he says P&W would be able to deliver "double digit" fuel savings for the 737.

Pratt & Whitney has reached a milestone in the development of its new geared turbofan engine after completing assembly of the first PW1524G scheduled to power Bombardier's CSeries aircraft.

The engine is now scheduled for delivery to Pratt & Whitney's facility in West Palm Beach, Florida later this month for the start of an eight engine validation and certification programme.

P&W plans to use the eight test engines during 24 months of testing to support certification and first flight of the CSeries in 2012. The manufacturer recently completed core testing of the geared turbofan, and has also performed critical module-level testing for the engine that includes running the fan drive gear system through a simulation of more than 60,000 takeoffs and landings. P&W's module testing also involved hundreds of hours of testing on the low and high-pressure compressor.

"We have worked closely with Pratt & Whitney engineers over the past two years to optimise engine performance as we integrated this powerplant into our airplane design," says Bombardier vice president of commercial aircraft programmes Ben Boehm. "We are very pleased with the progress of the engine programme to date and that Pratt & Whitney has completed first engine assembly on time."

First delivery of the CSeries is scheduled for 2013.

Beochien a écrit:
-Une remise à plat du système s'impose, il a atteint ses limites et ne sert plus qu'à alimenter des imbroglios inextricables ... le bread & butter des lawyers et autres parasites, quand plus personne ne maîtrise son produit !
JPRS

The process of certificating the first member of P&W's geared fan family will take place over the next 24 months, with the first three engines focused on evaluating the overall architecture of the engine in sea-level test cell environments.
In the second quarter of 2011, engine three will be fitted under the wing of the company's Boeing 747SP test aircraft and flown for a three-month test regime at altitude, evaluating the performance along with trials that include accelerations, decelerations and in-flight starts.
"The first six months are typically driven to validate that the engine works," says Bob Saia, P&W vice-president, next-generation product family. He says heavy certification testing with a fully conforming article for regulatory approval is to begin in mid-2011 and continue over the following 15-18 months.
During the 24 months, P&W expects to submit just under 300 certification reports for airworthiness approval and complete four to five builds of engine one during that period.
Saia says engine six or seven will take part in blade-out testing. This will take place just 10h into the engine's life before it is intentionally destroyed. During that test, one of the engine's bi-metallic, titanium sheathed blades will be thrown while the engine is operating at redline speed, destroying the powerplant, while validating the casing is robust enough to contain the explosive force of the failure.