The geared turbofan technology has Norwegian Air Shuttle's Jenssen taking a somewhat cautionary approach with respect to maintenance support. “We want to wait until we have a better understanding of how these engines will operate, before signing a maintenance service contract. At that time, we will look at either a power-by-the-hour or time-and-material contract.”
JetBlue Airways, which also selected PW1100G power for the 40 A320NEOs it has on order, for delivery beginning in 2018, sees minimal risk.
“Although the engine's geared turbofan technology has never had a commercial airline application, we believe there is little risk, since it has been used in the helicopter world for many years with no real problems,” says Larry Montreuil, director of corporate supply-chain management for JetBlue. “We're comfortable with the fact that the gearing system will help it run more efficiently, and, with the larger fan, it won't have to work as hard.”
He explains that initial concerns regarding spares support were alleviated by assurances from the original equipment manufacturer (OEM) that it is dual-sourcing components. “We are confident they have protected their supply chains, and have a high degree of comfort with that.”
Montreuil adds that the OEM is also under contractual obligation to provide technology insertion as the engine matures, particularly in such areas as thermal protection and advertised fuel burn.
JetBlue, explains Montreuil, has structured a “bifurcated maintenance agreement” with Pratt & Whitney on the new engine. Under the contract, JetBlue will pay a monthly fee to cover nonscheduled removals and minor engine maintenance. For major shop visits, the airline will pay a flight-hour rate for the hours flown for the specific engine that is in the shop. The airline, he reports, has a similar agreement with GE on the CF34s that power its Embraer 190s. In that case, JetBlue pays a flat fee at the shop visit.
Joe Maloy, director of propulsion engineering for US Airways, reports that one of the most important concerns that airlines have about new-technology powerplants is “engine performance retention,” which, he says, relates mostly to any changes with fuel-burn and EGT margins. (He says that, at this time, US Airways has neither the 737 MAX nor A320NEO on order.)
“When you start seeing fuel-burn increases, that's a sign that the engine's performance is deteriorating faster than expected. That, and narrowing EGT margins, need to be mitigated by the maintenance service contract with the OEM,” Maloy explains. “Performance retention is a much bigger concern than the risk of an inflight shutdown with the new-technology engines coming along.”
For the NextGen Leap and PW1100G, the unanswered question is component durability, Maloy stresses.
“What drives an engine off-wing is any failure in the accessories or hardware that surround the engine, rather than the condition of the gas generator,” he says. “Both the CFM Leap and the Pratt & Whitney PW1100G are being advertised to achieve a 15% or better mission fuel burn, but pushing an airplane to do that means that the engine will operate at a higher speed and a higher internal temperature. Although the components should be able to withstand the higher temperatures, will they be able to do this over a significant period of time?”