Rolls-Royce is urging Airbus and Boeing to reconsider plans to re-engine their respective A320 and 737 150-seat airliner families and instead concentrate on bringing all-new aircraft designs to the market more quickly.
The UK engine manufacturer is concerned that introducing interim "technology refreshes" of existing narrowbodies will have a net detrimental impact on the industry's ability to deliver step-change reductions in fuel-consumption and emissions, by delaying the introduction of new "highly integrated and optimised" aircraft.
"We have said for a while that we remain unconvinced that re-engining is the right answer for the industry - that it is going to give the net benefits that the industry needs," says R-R civil aerospace president Mark King.
"Whenever a product is made that is not as good as it could possibly be, we worry about whether that product can stand the test of time, and therefore about whether we are actually going to see the return on investment that we need to get," he says.
"One of the concerns with re-engining is whether it causes a delay in a new aircraft. All the analysis we do says that the right answer here is a new aircraft, and we don't want to delay that new aircraft."
R-R is working on all-new two- and three-shaft civil engine families, known as "Advance2" and "Advance3" respectively.
Advance2 covers the market for medium-sized business jets up to 150-seat narrowbodies and is being headed by the company's German subsidiary and two-shaft "centre of excellence" R-R Deutschland. Based the latter's E3E technology demonstrator core that has been under test for the past two years, Advance2 could deliver engines offering a "15-20%" reduction in fuel burn in 2016-17, says King.
"By putting a high technology fan similar to those that we use on large engines on the front of this core, we can actually build a good engine for the 150-seat market," says King.
"With a slightly smaller fan we can address the top end of the corporate market and the regional market, and by taking out a stage in the compressor we can use the same basic core to address the midsize corporate market as well. This is going to be a fundamental strategy for us going forward."
Advance3 is aimed at delivering new-generation three-shaft engines for widebody airliner developments anticipated for "the latter part of this decade", says King.
"Three-shaft still makes a very good prospect for the 150-seat market," he adds.
Advance3 is based around the Trent 1000 Environmentally Friendly Engine core technology demonstrator, which is due to be run in the fourth of this year. It also incorporates "lean-burn combustion" as well as technology from the ALPS low-pressure system demonstrator project.
Work is also under way on an open rotor engine that King says could be ready in the "first half of the next decade. It's the only real game changer relative to an advanced turbofan, and is the only thing that can deliver clear daylight - clear 10% better."
R-R has completed a third set of windtunnel tests of potential open rotor blade designs, and "we now firmly believe it will be quieter than any engine of an equivalent size that's flying today", says King.
Armed with the technologies that it expects its Advance2/3 and open rotor projects to deliver, R-R believes it will be able to meet a diverse range of potential requirements.
"What we've done is really focused down our technology programmes, and we're focusing specifically on two new engine families which we would anticipate entering service in the latter part of the decade," says King.
Although Airbus is exploring technologies for a longer-term all-new single-aisle replacement, it says that "airlines have made it clear that any fuel burn reductions available today would be welcome". As such it is working towards a decision later this year on whether to launch the A320 "new engine option", which could equip the narrowbody family with CFM International Leap X or Pratt & Whitney PW1000G geared turbofan engines.
However, International Aero Engines partners P&W and R-R continue to insist that a powerplant offer for the A320 NEO - and any subsequent all-new airframe - could come via the consortium.
"We still like IAE. It's a great venture, and it will keep selling engines at least until 2015-16, and they'll be in service for at least 25 years, so IAE is here to stay," says King.
"I think IAE is definitely an option for the route to market, and it's quite an attractive option, but as the market shapes up we'll see what is the best way of progressing," he adds.