After more than two decades of R&D, Pratt & Whitney believes its new geared turbofan engine will be ready to power the next generation of commercial aircraft, though it has yet to be accepted by major aircraft makers Boeing Co. or Airbus, according to Stephen Finger, the engine maker’s outgoing chief. The engine is just wrapping up flight tests on an Airbus A340.

The new engine, dubbed the PW1000G, uses gears to turn the fan, letting it run at slower speeds than conventional turbofan engines. This cuts fuel consumption by 15%. But so far, only Japan’s Mitsubishi and Canada’s Bombardier intend to use the engines on new regional jet models, which are due to fly commercially in 2013. The engine could also be scaled up to generate 90,000 to 95,000 lb of thrust or more, Finger said, making it powerful enough for the largest commercial planes available today.

Other aircraft companies could be questioning whether putting gears into a jet engine will reduce reliability, surmises Finger. “But the gearbox is not even in the top 10 causes of in-flight shutdowns or reliability issues. Most problems during testing have actually occurred in the turbine, the hot section”

But once it is proven reliable, Finger reckons the geared turbofan will power the next generation of single-aisle planes — the world’s biggest aircraft market — or whatever the major players plan to introduce next.