soon7x7
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AOG Composite Repairman?

Fri Nov 30, 2007 8:43 pm

I'm curious to find out if an A&P is required to be an AOG composite repairman. I'm sure it is preferred, but is it required and would I be correct in thinking that in short term the demand for such people will be reality if not already. My guess is that it is such a complex new science that most high time mechanics don't want to be bothered...is that a fair assumption?
 
474218
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RE: AOG Composite Repairman?

Fri Nov 30, 2007 9:33 pm



Quoting Soon7x7 (Thread starter):
I'm curious to find out if an A&P is required to be an AOG composite repairman.

Yes, why wouldn't they? A composite repair is nothing more than a standard fiberglass layup repair, but with different materials.
 
flipdewaf
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RE: AOG Composite Repairman?

Fri Nov 30, 2007 9:55 pm



Quoting 474218 (Reply 1):
Yes, why wouldn't they? A composite repair is nothing more than a standard fiberglass layup repair, but with different materials.

Fiberglass is a composite, did you specifically mean carbon fiber based composites soon7x7?

Fred
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474218
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RE: AOG Composite Repairman?

Fri Nov 30, 2007 10:10 pm



Quoting Flipdewaf (Reply 2):
Fiberglass is a composite, did you specifically mean carbon fiber based composites soon7x7?

I don't care what you call them, you repair them all the same way.
 
soon7x7
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RE: AOG Composite Repairman?

Fri Nov 30, 2007 10:50 pm



Quoting 474218 (Reply 1):

Take a thirty year old 737. All the composite parts were fibreglass and I'm guessing...epoxy based resins or did they start with polyester resin, surfboard type agent? If it was polyester then were they cold layups or were autoclaves used like in composite fabrication today? At present composite technology seems like so more an exact science than it used to be...the weave direction in carbon fibre and weave type seems to be so more critical for strength vs weight.Then the newer generation planes use multiple type fabrics in one part like, fiberglass, married to carbon fibre,with a layer of kevlar.Heat cured under negative pressure(vacuum). Some parts are even mated to metal either with carbon honeycomb, aluminum honeycomb or nomex. That all seems to me like a science all it's own and anyone that understands it well and can effect good repairs will be a valuable individual...NO?...Point is I am considering going for formal training in the stuff...think their exists a buck to be made in this and I am trying to glean this from mechanics in the field....that is my point...jerry
 
flipdewaf
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RE: AOG Composite Repairman?

Fri Nov 30, 2007 11:18 pm



Quoting 474218 (Reply 3):

I don't care what you call them, you repair them all the same way.

What, even paper honeycomb and foam based composites?

Fred
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474218
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RE: AOG Composite Repairman?

Fri Nov 30, 2007 11:30 pm



Quoting Soon7x7 (Reply 4):
Point is I am considering going for formal training in the stuff...think their exists a buck to be made in this and I am trying to glean this from mechanics in the field....that is my point...jerry

I agree that formal schooling would be the best. I also agree that there are many different types of composites and learning their differences and the similarities would be very helpful when working on the next generation of aircraft. My training came years ago, while I have tried to keep current, there are many new materials and procedures I would like to have the opportunity work with.
 
EMBQA
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RE: AOG Composite Repairman?

Fri Nov 30, 2007 11:54 pm



Quoting 474218 (Reply 1):
Yes, why wouldn't they?

Well... not in every case. It depends on what type of company you work. If you work for a Part 145 Repair Station you may not need one
"It's not the size of the dog in the fight, but the size of the fight in the dog"
 
soon7x7
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RE: AOG Composite Repairman?

Sat Dec 01, 2007 3:24 am



Quoting 474218 (Reply 6):

I'm glad you mentioned that materials and procedures have evolved over the recent past as I feel this has become a real science and not just anyone can be profficient at it, I feel it is the type of thing you must develop a feel for. Like lawyers (no offense to all you lawyers),existing are good ones and bad ones. Anyone can do this stuff if trained but to be good at it and in demand, ...that is something different...that to me is worth something...I have a friend that does nondestructive testing of aircraft...he xrays tail feathers of jet aircraft...I've never met anyone else that does it...he has a cornered market as far as I'm concerned...a real niche...anyway...thnx for your input...it helped greatly...j
 
474218
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RE: AOG Composite Repairman?

Sat Dec 01, 2007 4:02 am



Quoting Soon7x7 (Reply 8):
I'm glad you mentioned that materials and procedures have evolved over the recent past as I feel this has become a real science and not just anyone can be profficient at it, I feel it is the type of thing you must develop a feel for. Like lawyers (no offense to all you lawyers),existing are good ones and bad ones. Anyone can do this stuff if trained but to be good at it and in demand, ...that is something different...that to me is worth something...I have a friend that does nondestructive testing of aircraft...he xrays tail feathers of jet aircraft...I've never met anyone else that does it...he has a cornered market as far as I'm concerned...a real niche...anyway...thnx for your input...it helped greatly...j

You got it!

I use to tell my boss "the only thing better than being the best at doing something, is being the only one that does it.
 
miamiair
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RE: AOG Composite Repairman?

Sat Dec 01, 2007 1:30 pm



Quoting Flipdewaf (Reply 2):
Fiberglass is a composite

Not by itself. When you impregnate the cloth with resin, then it is a composite.

Quoting Soon7x7 (Thread starter):
I'm curious to find out if an A&P is required to be an AOG composite repairman

If you work for a 145 repair station you do not.

Composite repairs have evolved significantly than using fiberglass cloth and boat coat resin. There are several types, and here are a few categories: Room Temp cure, Elevated Temp cure, 250F and 350 F. The comon fibers are fiberglass, carbon and aramid (Kevlar). They each have their strengths and weaknesses and in many cases are combined to form hybrids.

PS, you don't want to use aluminum fasteners in a carbon fiber structure...
Molon Labe - Proud member of SMASH
 
soon7x7
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RE: AOG Composite Repairman?

Mon Dec 03, 2007 7:04 pm



Quoting Miamiair (Reply 10):

Three winters ago I taught myself this stuff, I have a 4x6 foot vacuum table, with thermo controlled element inside, got assortment of epoxies from all different sources,different fabrics and read many books...It was excititng to think how you can cut a section of fabric , mix a batch of liquid, shape some nomex honeycomb core, assemble and cook it in a vacuum environment for thirty minutes and out comes this incredibly light weight 3-d shape, then I primed with 2part bac epoxy and gave topcoat of akzo nobel bac gray....now all I need is a wind tunnel.Got old composite panels from boneyards and practiced repairing the damaged areas...Used router to excavate the damage cores and replaced w/ new ones...it's actually FUN!...I love working with the stuff and have considered getting formal training in it.PS...(in my teens I used to build surboards)...j
 
cloudy
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RE: AOG Composite Repairman?

Mon Dec 03, 2007 11:07 pm

In its 787 marketing materials on its site, Boeing says that there will be temporary "patches" available to apply in the field. These would be good for a few cycles, to enable the aircraft to reach a more capable repair facility. Normal "ramp rash" type accidents would be less likely to need significant repair or result in AOG than they would in an aluminum plane, according to Boeing.
 
soon7x7
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RE: AOG Composite Repairman?

Tue Dec 04, 2007 3:42 pm



Quoting Cloudy (Reply 12):

I think that with the increased use of composites in areas and structures that were formerly metal contstruction, aviation is going to experience a bit of a learning curve. At what price?...who knows, but all the static testing in the world just doesn't replicate normal cycles, exposure to the elements and simply the effect that time has on materials. Just as in American 587 in Rockaway.The repair procedure used on the mounting lug created a situation that in my opinion was complicit in the fin failure...I can't believe that event was entirely the result of the crews "radical" control inputs. If the original alloy tail feathers on that aircraft were never changed to composite, would that event have had the outcome that resulted?...I don't feel it would have.
 
tdscanuck
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RE: AOG Composite Repairman?

Thu Dec 06, 2007 2:37 am



Quoting Soon7x7 (Reply 13):
who knows, but all the static testing in the world just doesn't replicate normal cycles, exposure to the elements and simply the effect that time has on materials.

That's true, but a full set of materials tests goes *way* beyond static testing and includes fatigue (CA and VA cycling), environmental exposure, aging, etc. All the things you're mentioning are tested exhaustively prior to use.

Quoting Soon7x7 (Reply 13):
Just as in American 587 in Rockaway.The repair procedure used on the mounting lug created a situation that in my opinion was complicit in the fin failure...I can't believe that event was entirely the result of the crews "radical" control inputs. If the original alloy tail feathers on that aircraft were never changed to composite, would that event have had the outcome that resulted?...I don't feel it would have.

Why don't you think it would have? The force on the vertical fin, given the flight crews' inputs, far exceeded the ultimate strength of the vertical fin attachment. That's not a materials problem. If the vertical fin had survived that event, it would have been a sign that it was grossly overdesigned.

Tom.

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