Boeing 787 Superplane: Metal comes to the rescue of revolutionary plastic plane

A section of the Dreamliner undergoes wind tunnel tests, which proved unable to predict the forces experienced by a real plane during flight

HE midst of the deepest recession the aviation industry has ever seen is not the best time to discover that your revolutionary aircraft design has yet another serious structural weakness. But that's the predicament Boeing found itself in last week.

The company hopes its 787 airliner will be the first with a pressurised fuselage made from lightweight, fuel-saving carbon-fibre reinforced plastic (CFRP) composite materials, rather than aluminium.

But in 2008, the firm found that the 787's carbon-fibre "wingbox", the internal fuselage structure the wings attach to, was not strong enough and needed stiffening with metal spars. That redesign helped put back the plane's first flight by 15 months.

Then last week, other stress tests on an airframe showed that the plane needs strengthening at 18 points on either side of the fuselage just above the area where the wing attaches. Titanium or aluminium stiffeners are being developed to strengthen those "side-of-body" points.

The plane needs strengthening at 18 points just above the area where the wing attaches

"Data from the test did not match our computer model," says Boeing vice-president Scott Fancher. That highlights the difficulty of predicting the behaviour of advanced CFRP materials being used in very large structures for the first time.

Boeing says its computer model will now be modified in the light of the new data to help its engineers design the stiffeners. A new date for the 787's first flight has not been set.