With 5,000 hr. and 13,000 cycles on test engines, 10% them in flight, Pratt & Whitney (P&W) is dismissing claims by rival CFM that its engine can beat the geared turbofan (GTF) on fuel burn and maintenance costs.
Pointing out that CFM’sengine for the will not run until the fall, P&W President David Hess says “our NEO engine is flying and, in the most recent configuration, the fuel-burn numbers are half a percent better than predictions.”
Arguing “that’s a real engine, real testing and real data,” he says “there is no way on fuel burn and no way on maintenance cost that they can get the NPV [net present value] advantage they are claiming . . . unless they defy the laws of physics.”
CFM executive vice president Chaker Chahrour said here on Saturday that the Leap-1A will provide 1% better specific fuel consumption (sfc) than the PW1100G on the A320NEO, plus another 1% over the life of the engine as a result of better performance retention.
The/ joint venture is claiming a $4 million per aircraft NPV advantage, half from lower fuel burn and half from lower maintenance costs—the latter based largely based on CFM’s estimates for costs related to the PW1100G’s gearbox.
But Hess says P&W’s fan-drive gearbox will not need maintenance until the engine’s second shop visit, “and the engine will never come in for a gearbox.” Additionally, 75-80% of sales agreements include per-hour maintenance agreements under which Pratt is “guaranteeing the cost to airlines.”
“We will be on our weight and fuel-burn guarantee at entry into service, which has not happened for some time in their industry,” he says. “And we seem pretty confident on the maintenance data. We are very confident in our assertions and are guaranteeing them in contracts.”
Pratt has more than 3,500 PW1000G-series engine on order and option and Hess expects to add more over the course of the air show. The GTF family has five applications:, (MRJ), A320NEO, MS-21 and now ’s second-generation E-Jet.
The next-generation version of thewill use a derivative of the MRJ’s 56-in.-fan, the 15,000-17,000-lb.-thrust PW1200G, while the larger members of the new E-Jet family will use a derivative of the CSeries’ 73-in.-fan, the 21,000-23,000-lb.-thrust PW1500G, he says.
Flight-testing, first on the CSeries and then of the A320NEO engines, has resulted in deletion of the variable-area fan nozzle (VAFN), which Pratt had thought would be needed to provide enough flutter margin for the large-diameter fan.
But Hess says the latest hybrid-metallic fan blade has much better flutter characteristics than expected and sufficient margin to eliminate the VAFN “and get rid of the complexity and weight.” NEO test engines are now flying with the nozzle locked, but design changes will delete that feature from production engines.
“The engine is proving itself in flight-test,” Hess says. Meanwhile, Pratt has plans in place for a next-generation GTF to extend the fuel-burn benefits from the current 15% reduction to 25% in 10 years.
The initial PW1000G series tackles propulsive efficiency by introducing the geared fan. The next step will focus on improving thermal efficiency through “higher pressure ratios, high OPR [overall pressure ratio] cores, better materials and coatings,” he says.
Key to this will be the U.S. Air Force Research Laboratory’s Adaptive Engine Technology Demonstration (AETD) program, under which Pratt will run a variable-bypass combat engine demonstrator by 2016. AETD “will demonstrate technologies for military and civil engines and give us our next-generation core and materials,” Hess says.
“AETD is strategically important,” he notes. “We are getting investment help from the government, but we are putting a lot of our own money into it also.”