Beaucaire From Syria, joined Sep 2003, 5252 posts, RR: 26 Posted (8 years 3 months 3 weeks 12 hours ago) and read 1647 times:
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 ?
Eilennaei From , joined Dec 1969, posts, RR: Reply 2, posted (8 years 3 months 3 weeks 5 hours ago) and read 1575 times:
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??
Boeing nut From , joined Dec 1969, posts, RR: Reply 6, posted (8 years 3 months 3 weeks 4 hours ago) and read 1522 times:
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.
Dl757md From United States of America, joined May 2004, 1555 posts, RR: 18 Reply 7, posted (8 years 3 months 3 weeks 3 hours ago) and read 1475 times:
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.
ViveLeYHZ From Canada, joined Dec 2004, 194 posts, RR: 10 Reply 8, posted (8 years 3 months 3 weeks 2 hours ago) and read 1454 times:
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.
Dl757md From United States of America, joined May 2004, 1555 posts, RR: 18 Reply 10, posted (8 years 3 months 2 weeks 6 days 21 hours ago) and read 1371 times:
LongbowPilot From United States of America, joined Jan 2005, 577 posts, RR: 4 Reply 12, posted (8 years 3 months 2 weeks 6 days 20 hours ago) and read 1338 times:
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 From , joined Dec 1969, posts, RR: Reply 13, posted (8 years 3 months 2 weeks 6 days 17 hours ago) and read 1295 times:
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.
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