A350 XWB cabin door fitting switched from aluminum to PEEK

PEEK 90HMF40, from Victrex, is used to injection mold a carbon fiber-reinforced fitting that connects the outer skin to points on the internal bracing structure of the cabin door.

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Victrex (West Conshohocken, PA, US) reports that Airbus Helicopters is replacing aluminum in a fitting in the aircraft door of the Airbus A350-900 with a high-modulus, carbon fiber-reinforced PEEK.

The bracket, now manufactured from VICTREX PEEK 90HMF40, has been developed by Airbus Helicopters and is in serial production for commercial use after receiving the relevant component qualification. The successful substitution of metal has resulted in a 40% reduction in weight and costs. The injection-molded polymer solution replaces the higher cost manufacture of the bracket machined from an aluminum block.

The fiber-reinforced polymer (FRP) structure of the A350 XWB’s aircraft door uses an outer skin coupled with a bracing structure on the inside. The fitting connects the outer skin to points on the internal bracing structure. The two components form a box-type support structure to exploit the maximum geometrical moment of inertia.

Christian Wolf, head of Airplane Doors Research and Technology at Airbus Helicopters, explains the operation and significance of the PEEK component: “In terms of the standard load case, i.e. the internal cabin pressure, this point-type joint reduces the deformation on the outer skin, thereby maintaining the aerodynamic quality of the aircraft door. All components in the aircraft door are of a singly-redundant design. If a component near the bracket fails, the bracket will provide an alternative path for transferring structural loads and is therefore part of the aircraft’s primary structure.”

Victrex says the PEEK withstands the moisture that continuously accumulates inside aircraft doors, whereas aluminium, which is prone to corrosion, needed a special surface coating to prevent corrosion. “The suitable material, supplied by Victrex, as well as their expertise and collaboration with their materials experts have contributed to the successful development and component qualification. The expertise gained from the initial use of fiber-reinforced PEEK can be transferred to other components and to other areas of application with similar requirements,” says Wolf.

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