Tokyo-based Toray Industries, a key supplier of composite structures for the 777, has been selected by Boeing to provide prepreg composites for the primary structure of the 7E7.

Composites will make up more than 50% of the structure of the 7E7 by weight, with the balance made up of 24% aluminium alloy, 11% titanium and around 8% steel. The selection of Toray, which produces the high-strength carbonfibre and toughened epoxy resin-based prepreg hybrid material used in the 777 empennage and floor beams, comes as Boeing begins preparing its composite-based design and test work for production with its manufacturing partners.

"We are now focusing on how to transfer all that into the 7E7 configuration, and how we translate it into specific parts of the wing and fuselage into manufacturing," says director of technology integration for the 7E7 Al Miller. He says the 7E7 heralds an evolution in the use of composites from the 777.

Aside from being used for the floor beams and the entire empennage, composites are also used for flaps, cowlings, fairings, ailerons, fixed leading edges and undercarriage doors on the 777. Carbonfibre and toughened epoxy resins will make up the bulk of the composites expected to be used in the fuselage of the 7E7, with TiGr, a titanium/carbonfibre composite laminate to be used in the wings.

Miller says: "A variety of structural elements are being made for the fuselage, wings and empennage to validate manufacturing, design and properties. We are in the process of completing these with our partners."

Boeing also believes it is making headway trying to convince some airline sceptics that composite structures can withstand the day-to-day abuses of the flight ramp and airline operations. "There is a mistaken belief that composites are brittle and fragile - like glass. That's not true at all. For the 7E7 we require visible damage as the key to maintenance or repair action on a given area. In other words, if it doesn't leave a visibly damaged part we would not require our operators to do anything."


Source: Flight International