Beaucaire
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Are Composite Aircraft Difficult To Repair?

Sun Jan 30, 2005 2:53 am

Considering the lesser elasticity and flexibility of compound composite aircraft like the 787,some engineering concerns remain about the complexity of repairs.
Aluminium bends and can be relatively easily repaired.How difficult will be 787 cell- structure repairs ?
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Starlionblue
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RE: Are Composite Aircraft Difficult To Repair?

Sun Jan 30, 2005 9:51 am

Just use some superglue  Big grin
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
eilennaei
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RE: Are Composite Aircraft Difficult To Repair?

Sun Jan 30, 2005 9:56 am

Call for the Boeing guys to fly in a new sub-structure, I should think. The pressurized composite parts -- well, perhaps the FAA has already mandated something??

regards,
Eilennaei
 
EMBQA
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RE: Are Composite Aircraft Difficult To Repair?

Sun Jan 30, 2005 10:03 am

Composites are easy to work with, but it does take proper training.
"It's not the size of the dog in the fight, but the size of the fight in the dog"
 
eilennaei
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RE: Are Composite Aircraft Difficult To Repair?

Sun Jan 30, 2005 10:45 am

We are, I believe, discussing a very special composite part here. Basic composite repair courses are offered widely for standard aviation parts.
 
VS340
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RE: Are Composite Aircraft Difficult To Repair?

Sun Jan 30, 2005 10:52 am

they are not difficult to do at all, they just are very time consuming, and require expensive specialized equipment
 
Boeing Nut
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RE: Are Composite Aircraft Difficult To Repair?

Sun Jan 30, 2005 10:55 am

As EMBQA stated, repairs are easy with the right training. I remember some time back that a Beechcraft Starship had slid off a runway in snowy conditions. The laning gear had been sheared off. The aircraft was repair in a matter of days with hand tools.

So I'm going to bet that any damage that occurs to a 787 will be repaired easily. I'm also certain that Boeing is going to deliberately damage one of the "prototypes" and repair it and see what happens during the test phase.
I'm not a real aeronautical engineer, I just play one on Airliners.net.
 
dl757md
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RE: Are Composite Aircraft Difficult To Repair?

Sun Jan 30, 2005 12:16 pm

To answer the question in the topic title, composite structures are not inherently harder than aluminum structures to repair. The process is quite different for obvious reasons and requires a different set of skills. This in of itself does not make it more difficult.

aluminum bends and can be relatively easily repaired.

Yes aluminum bends and can take a set without failing. That doesn't mean that the part can be bent back and remain servicable. Bent aluminum parts must be cut out and are then replaced by repair pieces spliced into the surrounding undamaged area. This is pretty straight forward but is by no means a quick process.

Composites on the other hand flex but don't take a set before failing. So you won't see bent composites. They will deflect under a load and return to their original shape unless loaded to the point of failure at which point they break, delaminate, or crack. The damaged area can then be removed and repair material bonded to the surrounding undamaged area. Sounds pretty similar to how aluminum is repaired? The major difference is how the repair material is joined to the existing structure. Aluminum mainly uses mechanical fasteners for the connection while composites use epoxy bonding for this. A third category, metal bonded structures, uses elements of both for accomplishment of the repairs.



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ViveLeYHZ
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RE: Are Composite Aircraft Difficult To Repair?

Sun Jan 30, 2005 12:37 pm

One of the problems people encounter with composites is their brittleness, which essentially means that a part can fail with little or no prior warning. On the other hand, because composites do not have plasticity, engineers can easily predict their behaviour and failure loads.

Another problems with composite materials is the large number of failure modes possible. They can crack, delaminate, break, etc. Some failure modes are not easy to predict.

Repairing composites at this time is more of an art than an exact science, unlike metal structures. But a great deal of research is being undertaken in many institutes on this topic.
 
Beaucaire
Topic Author
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RE: Are Composite Aircraft Difficult To Repair?

Sun Jan 30, 2005 5:10 pm

@ViveLeYHZ,@Dl757md
Thanks a lot for giving me some insight on this matter- I still feel a little intrigued by the complexity of these repairs..
Please respect animals - don't eat them...
 
dl757md
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RE: Are Composite Aircraft Difficult To Repair?

Sun Jan 30, 2005 5:48 pm

Try some of the sites on this page to satisfy your intrigue.
http://www.google.com/search?hl=en&q=composite+repair

Dl757Md
757 Most beautiful airliner in the sky!
 
aerosol
Posts: 497
Joined: Mon Oct 23, 2000 10:31 pm

RE: Are Composite Aircraft Difficult To Repair?

Sun Jan 30, 2005 6:48 pm

To repair maybe, but I have not read a proper answer if they can be scrapped...
 
LongbowPilot
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Joined: Mon Jan 17, 2005 4:16 am

RE: Are Composite Aircraft Difficult To Repair?

Sun Jan 30, 2005 6:59 pm

I was working in ATL one day and saw a 763 having a composite patch being placed on the #1 nacelle. They had it set up and plastic bag over the area and 4 shop lights under the plastic bag to probably keep the air dry so it would cure right.

 
eilennaei
Posts: 1003
Joined: Tue Nov 23, 2004 8:41 am

RE: Are Composite Aircraft Difficult To Repair?

Sun Jan 30, 2005 9:50 pm

So has the FAA mandated anything regarding composite parts undergoing pressure cycles in a commercial airliner? The Adam A500 at least is in the air, but is a much smaller craft.

regards,
Eilennaei

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