Repairing the Charred 787 Dreamliner.....

How do you fix fire damage on a 787 when the body is constructed as one piece of composite material? 

My suggestion would be to toss it in the landfill with all the other junk. But Boeing is actually going to try and repair it. 

This is going to turn out just great….I can already tell. This plane is a health hazard when it is brand new. After a fire and a never before attempted repair…oye.


http://seattletimes.com/html/businesstechnology/2022097759_787repairxml.html


Boeing has begun the delicate, expensive and crucial process of repairing the 787 Dreamliner that was badly damaged by a fire last July.

Because the 787 is the first large commercial jet made from carbon-fiber-reinforced plastic composites, there’s no precedent for the substantial damage

To begin the repair, the jet maker several weeks ago fabricated a full rear fuselage barrel in its North Charleston, S.C., factory.

It then cut out the crown section to supply a skin patch for the repair of the jet in London, said a Boeing engineer, one of the two people with knowledge of the details.
Several other pieces of composite skin were cut from the same barrel section to provide an inventory of repair patches for future use.

A different Boeing engineer, who is an expert in composite repairs, said putting in the patch will be complex and difficult.

But he said it would have been even more trouble to take the other approach — disconnecting all the wiring, air and fuel systems and then inserting a full fuselage section that would mesh exactly with the section in front of it and the tail behind it.
On condition of anonymity, (nobody wants their name anywhere near this pending debacle) this engineer explained the likely repair process.

Boeing will cut out the skin damaged by the fire probably in a rectangular cut with rounded edges, he said.

It will cut the patch to the same size and shape and drop it into the space as a plug. The tiny gap around the patch will be filled with paintable sealant that will stretch and compress as the fuselage is pressurized and unpressurized. (What could be safer then glue)

Then mechanics will work on the inside, gluing a splice plate to the original skin and to the patch, overlapping both by about 4 inches.

The glue is a superstrong adhesive that is cured using heat blankets that are held under pressure by vacuum bags applied to the area.

Heatcon makes the electronic boxes used to monitor the temperature and pressure, which must be controlled carefully for hours as the adhesive hardens.

In addition to the skin patch, Boeing’s mechanics must also repair the stringers — the stiffening rods that run longitudinally along the fuselage — which will be cut when the damaged section is removed.

They’ll have to lay wet composite tape precisely in the shape of the stringer at the point where it was cut and cure it to hardness, again using heat blankets and vacuum bags maintaining the precise temperature and pressure. (Tape and glue….Sounds like a great plan)

All this work will be intricate and must be done precisely to ensure the glue sets as expected and the repair is safe.

University of Washington professor Mark Tuttle, director of UW’s Center of Excellence for Advanced Materials in Transport Aircraft Structures, said proving a bonded repair is sound can be difficult. (Who wants to get onboard and take the first test flight? Come on raise your hands nice and high)

“One issue with adhesive bonding is you can inspect the bond with ultrasonic inspection and find no gaps or voids, but nevertheless the strength of the bond is lower than anticipated,” he said. (I am sure it will all get sorted out at 35,000 feet. Put on some headphones and enjoy the flight)

He said Boeing will stress-test the result after the repair is finished, including flight tests with instruments attached to measure the strain on the patch.

The Federal Aviation Administration (FAA) will likely have to sign off on the airworthiness of the jet after repair, Tuttle said. The FAA did not respond to an emailed query before deadline. (The FAA doesn’t want their name anywhere near this. The FAA already said the plane was safe before the fire, like they have any credibility left)

The Boeing engineer with knowledge of the repair preparations said the company will gain valuable experience from this repair of a major composite skin section. (Yes once this repair proves to be a failure they will know exactly what not to do for next time a 787 burns)

“Chances are there’ll be issues along the way (I can guarantee it) as they figure out their expertise,” (Expertise…Hahahahaha ) he said. “It’s all brand new ground.”