Next-gen narrowbody engines may burn too hot for nacelle composites

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New commercial turbofans may produce too much heat for their supporting nacelles to rely on carbon epoxy materials, a Spirit AeroSystems executive says.

The Wichita-based supplier of aerostructures, including nacelles, has completed trade studies on nacelle designs with the Airbus on the A320neo narrowbody, John Pilla, senior vice president and general manager for the Spirit AeroSystems propulsion segment, told analysts at the company's "investor day" on 7 March.

The studies showed that the new turbofans - Pratt & Whitney's PW1100G geared turbofan and CFM International's Leap-X - burn 10-37.8°C (50-100°F) hotter than current engines, Pilla says.

The temperatures may exceed the limits of carbon fibre epoxy, the lightweight, high-strength materials that are used for current nacelles, he adds.

Spirit AeroSystems is looking at other materials, such as titanium honeycomb acoustic panel, that can absorb the higher temperatures, but are also light and strong enough for the nacelle application.

The "potential replacement will go higher temperature over traditional graphite epoxy," Pilla says.

Pilla's comments indicates another technical complication in the transition to the next generation of turbofan engines for existing narrowbodies.

Both Airbus and Boeing have launched re-engining programmes rather than develop an all-new narrowbody to replace the A320 and 737 Next Generation families.