Airbus is looking to its complex supply chain for even sharper performance as it seeks to smooth out any remaining kinks in its production system. One of the critical partners, GKN Aerospace, is responsible for the A350 aft composite spar and fixed trailing edge.
GKN bought the wing components manufacturing facility at Airbus's Filton site in January 2009 and has built a separate, dedicated factory for its A350 work 8km from the Filton plant.
Currently employing almost 270 at a production rate of 1 aircraft per month, the workforce at the Western Approaches facility is expected to grow by another 60 or more as the rate increases on the A350 as well as for the composite wing on the A400M military airlifter, major sections of which are also manufactured there.
GKN Aerospace has also invested in its Munich facility where the inboard and outboard flaps (including skins, spars, ribs and leading edges) are manufactured using the advanced tape laying and forming processes.
“This industrialization was a first for GKN,” says Vice President Colebrook. “Normally you'd take the spar to a jig, then take it out and continue to the next jig until it is built. With this one, the spar is loaded and locked into a bespoke jig. Then the jig moves down from station to station to hold the highest level of tolerance before we take it out and pop it into a final turn-over jig to deliver it to Airbus. The key tolerance is the hinge line of the trailing edge. We're making it to within +/- 0.15 mm over a roughly 30-meter-long assembly”.
Each of the two wings in the shipset is made up of three components; an inner, mid and outer spar section. Mounted on specially designed manually guided vehicles, the jigs containing the individual spar sections are picked up and moved through the production process.
The three sections combine to produce a trailing edge assembly 27 meters long and weighing about 1,800 kg.
Assembly of each section begins when five-axis AFP machines, made by M. Torres of Spain, wind composite tows from up to 16 bobbins onto a Cytec-made rotating composite mandrel. The machine is programmed to lay varying thicknesses to tailor the structure for stress requirements and provide foundations for parts such as rib attachment points along the spar.
“The A350 inner spar is the thickest we build. It undergoes a hard structural cure and is then prepared for the addition of sacrificial material before being cured again in a secondary cure.”
Left and right spars are laid up simultaneously on the mandrel in a process that takes up to eight 24-hr. working days. The units are then “de-bulked” to remove any trapped air, and inspected.
The formed parts are loaded onto an Invar tool for curing in the autoclave. Once cured, parts go into one of two five-axis composite machining tools which combine waterjet and conventional cutting devices before undergoing non-destructive testing for porosity or inclusions.
The spars are then painted with primer, and metal rib posts are added before completion with trailing edge gear and flap fittings.
Means investments planned include a 2nd autoclave, a 3rd five-axis composite machining tool and a 4th AFP machine.
GKN Aerospace technical director Richard Oldfield, who previously worked for Airbus, said that including the design and manufacture of the A380's wings, the A350 program is the most technically challenging he has been involved in.
A higher build rate on an established product such as the A320 can be achieved with relative ease as "when you really understand the technology, ramping up is just an investment debate", he said. However, on the A350 the question is, "how do you ramp-up emerging technology?" he added.
Based on article "A350 Wing Sub-Assembly Ramps Up At New GKN Site" published on Aviation Week
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