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QuarkFly
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Ramp Rash on 787 and A350

Fri Jul 27, 2018 2:18 am

Now that we have hundreds of composite 787 in service and A350's too, with seven years of experience -- I'm interested to know how the composite "ramp-rash" issue ever developed...

During the 787 design period, I remember some concern about ground vehicles or other things striking the aircraft in typical daily ramp usage...that in the case of aluminum may just cause a dent or require a doubler....but do more serious damage to composites -- especially around doors and cargo loading areas of the aircraft.

Has this been an issue to anybody's knowledge...is there a lot of composite line maintenance going on that we do not hear about? Or was the issue overblown and the aircraft handling minor bumps and bruises like champs? I know both A and B developed quick composite repair kits -- and training for maintenance personnel.

I hope we don't have to ever hear about a improperly installed composite repair for ramp-rash -- causing a decompression or major delamination. Have not heard about this issue for a while...is composite ramp-rash actually a non-issue?
Always take the Red Eye if possible
 
BravoOne
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Re: Ramp Rash on 787 and A350

Fri Jul 27, 2018 12:46 pm

They have special tools to discover it and fix it.
 
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Matt6461
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Re: Ramp Rash on 787 and A350

Sat Jul 28, 2018 4:12 am

So am I right in thinking this relates to the shear vs. Tension/compression strength per unit of aluminum vs. CFRP? does anyone have the figures for the various moduli?
 
FrmrKSEngr
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Re: Ramp Rash on 787 and A350

Sun Jul 29, 2018 2:00 am

Matt6461 wrote:
So am I right in thinking this relates to the shear vs. Tension/compression strength per unit of aluminum vs. CFRP? does anyone have the figures for the various moduli?


Google has lots of information for the raw fiber, and pre-pregs. Here is a site that came up: https://www.build-on-prince.com/carbon-fiber.html

The properties for specific lay-ups (and the the orientations of the lay--ups) is closely held by Boeing and I imagine Airbus.
 
stratclub
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Re: Ramp Rash on 787 and A350

Sat Nov 17, 2018 1:19 pm

I really think the jury is still out on the ramp rash question. If the Ethiopian ELT fire repair is any indication, it does not look like composite airframe repairs are going to be cheap and easy.

"People with knowledge of the repair method said Boeing fabricated a full rear fuselage barrel in its North Charleston, S.C., factory, then cut out a large patch to replace the fire-damaged skin of the Ethiopian jet.
https://www.seattletimes.com/business/e ... re-damage/

Sorry about the pay wall.

Non pay wall final report of the Ethiopian ELT fire. https://assets.publishing.service.gov.u ... ET-AOP.pdf
 
FGITD
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Re: Ramp Rash on 787 and A350

Sat Nov 17, 2018 9:32 pm

I think the issue was somewhat abated by changes in procedure. Every 787 operator I've worked with has an extremely strict no touch policy. Even the equipment you could safely bump into a 777 or 330 (for example) can't touch. It changed the mentality completely, at least where I'm based, and if anything, has had a positive effect on minimizing all ramp damage. Rather than going type by type, everyone is told not to touch any airplane.

I also think there may have been some initial overestimating of just how much contact there is on a regular basis.
 
stratclub
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Re: Ramp Rash on 787 and A350

Sun Nov 18, 2018 7:03 pm

Even on composite aircraft, ramp rash does happen. The problem is that with a metal airframe repair techniques are well understood and operators have the tools and techniques to implement repairs. With composite aircraft the concepts of repair will require some ongoing technological development to become better understood and implemented.
https://www.compositesworld.com/article ... -on-basics
http://www.tc.faa.gov/its/worldpac/techrpt/ar03-74.pdf

If the Ethiopian airlines ELT fire damage was on a metal aircraft, the repair would not have required an entire barrel section to be manufactured so that a repair part could be cut out of it.
 
luv2cattlecall
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Re: Ramp Rash on 787 and A350

Tue Nov 27, 2018 1:43 am

FGITD wrote:
I think the issue was somewhat abated by changes in procedure. Every 787 operator I've worked with has an extremely strict no touch policy. Even the equipment you could safely bump into a 777 or 330 (for example) can't touch. It changed the mentality completely, at least where I'm based, and if anything, has had a positive effect on minimizing all ramp damage. Rather than going type by type, everyone is told not to touch any airplane.

I also think there may have been some initial overestimating of just how much contact there is on a regular basis.


This might be a novice question, but why wasn't no-touch always a policy?
 
FGITD
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Re: Ramp Rash on 787 and A350

Tue Nov 27, 2018 2:49 am

luv2cattlecall wrote:
FGITD wrote:
I think the issue was somewhat abated by changes in procedure. Every 787 operator I've worked with has an extremely strict no touch policy. Even the equipment you could safely bump into a 777 or 330 (for example) can't touch. It changed the mentality completely, at least where I'm based, and if anything, has had a positive effect on minimizing all ramp damage. Rather than going type by type, everyone is told not to touch any airplane.

I also think there may have been some initial overestimating of just how much contact there is on a regular basis.


This might be a novice question, but why wasn't no-touch always a policy?



Generally speaking, it usually was the policy. But things like belt loaders, jetbridges and deck loaders would periodically bump into the plane, either from the aircraft moving or simply poor positioning. And it was regarded as a "it happens, tell the engineer to take a look" situation. And this still happens sometimes, with other types.

787 took that to a "if you bump the plane at all, you'll cancel the flight while they spend hours inspecting it" level.

As I said, it really seemed to change the mentality.


For a completely solid answer though, I don't fully know. 787s have been flying for longer than I've worked at any airport, so they predate me.
 
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trpmb6
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Re: Ramp Rash on 787 and A350

Tue Nov 27, 2018 2:07 pm

The biggest challenge for composites is incidental damage producing subsurface delaminations that are not visible on a pilot walk-around, or may appear to be a non-issue to the offender and thus not get reported (for fear of retribution). To dissuade any concerns out there, we analyzed for such things and have such things accounted for in our testing so no need to worry (Note: this doesn't mean you have a blank check to not report any damage or incidental contact that occurs!).

I once heard that technically the 787 could hold the strains due to limit pressure with just a single ply, but you wouldn't be able to pressurize such a design, and so many other design considerations (mostly discrete source damage sources) come into play that you end up with the stackup we have now.
 
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zeke
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Re: Ramp Rash on 787 and A350

Wed Nov 28, 2018 10:19 am

A good mechanic will apply a topical ointment which helps their rash go away.
Human rights lawyers are "ambulance chasers of the very worst kind.'" - Sky News
 
stratclub
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Re: Ramp Rash on 787 and A350

Wed Nov 28, 2018 1:17 pm

zeke wrote:
A good mechanic will apply a topical ointment which helps their rash go away.

No. A good mechanic will consult the MMEL first. Also, there may be a "Band-Aid" fix in the FIM or MM. :bouncy:
 
M564038
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Re: Ramp Rash on 787 and A350

Wed Nov 28, 2018 9:21 pm

Air India ran one of their 787s into a building @Stockholm tonight, so that might be something to follow regarding this.
 
stratclub
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Re: Ramp Rash on 787 and A350

Thu Nov 29, 2018 2:37 am

From what I know about aircraft structural repair, the concept of structural repair on composite airframes could be pretty dismal in cost in the actual implementation. Boeing seems to say that composite repair is no big deal and tradition bolted repair schemes as are used on a metal airframe can be easily implemented. I would say, complete nonsense. See my previous post.
 
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Francoflier
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Re: Ramp Rash on 787 and A350

Thu Nov 29, 2018 3:30 am

One of the issues with composite airframes, even before repair, is detecting the damage.

Whereas metal tends to bend and dent fairly quickly and visibly when hit, composite materials have a tendency to elastically return to their original shape even if internal damage or delamination has occurred. Basically, if someone hit the side of an airplane a bit hard, chances are no one could tell from looking at it and unless this person does the right thing and report it, it could go unnoticed for a while.

There are handheld ultrasound scanners (at least I think they're ultrasound, could be mm wave or even x-ray...) that allow engineers to look for hidden delamination in CRFP panels, but they have to know where to look...
I'll do my own airline. With Blackjack. And hookers. In fact, forget the airline.
 
WIederling
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Re: Ramp Rash on 787 and A350

Fri Nov 30, 2018 3:03 pm

zeke wrote:
A good mechanic will apply a topical ointment which helps their rash go away.

ROFL.
My XYL had the use of a car i owned. She pranged it slightly while backing into a low granite block.
She was pretty downbeat about this and to raise her spririt ( ameliorate the damage ) I told her to apply some
zink paste "PenatenCreme" on the damage ( slight dent and paint scraped off ).
5 years later when I scrapped the vehicle the zink paste was still "on" :-)
Murphy is an optimist
 
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trpmb6
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Re: Ramp Rash on 787 and A350

Fri Nov 30, 2018 4:09 pm

Francoflier wrote:
There are handheld ultrasound scanners (at least I think they're ultrasound, could be mm wave or even x-ray...) that allow engineers to look for hidden delamination in CRFP panels, but they have to know where to look...


Ultrasonic I believe. (X-ray is too expensive and not reliable)
 
WIederling
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Re: Ramp Rash on 787 and A350

Fri Nov 30, 2018 4:47 pm

trpmb6 wrote:
Francoflier wrote:
There are handheld ultrasound scanners (at least I think they're ultrasound, could be mm wave or even x-ray...) that allow engineers to look for hidden delamination in CRFP panels, but they have to know where to look...


Ultrasonic I believe. (X-ray is too expensive and not reliable)


Xray (usually) doesn't show layering damage.
When going for welding engineer qualification the limitations were shown in quite a sobering way.
You can work a weld that looks perfect, xrays perfect and when the welded assembly is thrown down
it disassembles into the initial part A, part B and the weld as new part C.
Murphy is an optimist
 
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trpmb6
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Re: Ramp Rash on 787 and A350

Fri Nov 30, 2018 7:39 pm

WIederling wrote:
trpmb6 wrote:
Francoflier wrote:
There are handheld ultrasound scanners (at least I think they're ultrasound, could be mm wave or even x-ray...) that allow engineers to look for hidden delamination in CRFP panels, but they have to know where to look...


Ultrasonic I believe. (X-ray is too expensive and not reliable)


Xray (usually) doesn't show layering damage.
When going for welding engineer qualification the limitations were shown in quite a sobering way.
You can work a weld that looks perfect, xrays perfect and when the welded assembly is thrown down
it disassembles into the initial part A, part B and the weld as new part C.


If I recall it's quite expensive too because you have to make a bunch of reference standards to compare against. Which pretty much kills the point.

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