- PEEK fitting connects outer skin to points on internal bracing structure
- 40% reduction in weight and costs
- Moisture: aluminium needs special surface coatings, PEEK not
Airbus Helicopters is replacing aluminum in a fitting in the aircraft door of the Airbus A350-900 with a high-modulus, carbon fiber-reinforced high performance polymer. The brackets, now manufactured from PEEK (polyetheretherketone), 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 part replaces the higher cost manufacture of the bracket machined from an aluminum block.
PEEK fitting connects outer skin to points on internal bracing structure
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. A fitting, now manufactured from Victrex PEEK 90HMF40 thermoplastic, 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.
“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”, explains Christian Wolf, Head of Airplane Doors Research and Technology at Airbus Helicopters.
40% reduction in weight and costs
By using the carbon fiber reinforced Victrex PEEK 90HMF40 polymer instead of the aluminium previously used, Airbus Helicopters has successfully manufactured an equivalent component that provides a range of benefits. Weight and production costs have each been reduced by 40%. In addition, joining the PEEK component, instead of an aluminum component, to a thermoset makes drilling much easier. Optimized carbon fiber reinforced plastic (CFRP) drills improves the quality of the holes compared with the previous solution.
Aluminium needs special surface coatings, PEEK withstands moisture
Specified by Airbus, Victrex PEEK 90HMF40 withstands the moisture that continuously accumulates inside aircraft doors, whereas aluminium, which is prone to corrosion, needed a special surface coating to prevent corrosion.