B787 repair question

[Jo90]

Reading about the high tech all composite fuselage of the 787 I can't help wondering how it will be possible to repair the hull after Johnny Groundcrew punctures it with the corner of the honey wagon or whatever.
Anyone enlighten me?

[hollywood285]

duck tape??

[Spanner Turner]

Jo90,

Mate, I've been thinking the same thing myself for quite a while now. It would seem to me that when it comes to the pressurised area of the fuselage, there will be no more quick patch repairs to get you on your way. Carbon, graphite and'or kevlar would generally require lots of heat, vaccuum and time to effect a structural repair. Having said that, one would hope that Boeing have put as much research into the maint/repair of these plastic fantastics as they put into the thought/design/promises of light weight/cost saving.

Not much point having a lightweight/economical aircraft saving you lots of money for a couple of years if the first time the fuselage gets damaged by a catering truck/pushback tug/fuel truck/hangar door etc,etc it stays on the ground for weeks or months waiting for a repair scheme!
Believe me, they all get hit sooner or later- as sure as the sun coming up!
With a "traditional" aluminium skin/structure, the worst hits/holes/dents can be fixed with new metal, rivets and some skilled (or even unskilled) labour in a relatively short time. A big hole in a composite structural area would not be quite so easy in my opinion. Like i said, i'll reserve judgement until manufacturer's start coming up with repair schemes but i wouldn't want to be the first to drive a truck into one!

[Wizofoz]

Do you really think that Boeing would invest billions developing the aircraft, and the airlines would order hundreds of them, if repair-ability hadn't been thought of?

In the first instance, the hull is less prone to damage as it is harder that conventional aluminum structure.

Secondly, a repair regime is part of the package. For a normal type of "ding" such as running a baggage loader into the hull might cause, a patch can be applied that takes 30 minutes to repair and lasts five years.

A major hull damage can be repair on an overnight service and is good until the next full strip down (about equivalent to a "D" check, but at longer intervals.)

Repairablility and therefore avoiding down time is actually one of the (many!) things that is making the 787 a revolution in the industry.

[tubby linton]

You might need one of these:
file:///C:/DOCUME%7E1/CMJ%7E1.THE/LOCALS%7E1/Temp/moz-screenshot.jpghttp://www.hobbylinc.com/gr/amt/amt31837.jpg

[Pinkman]

WizofOz
I am not a composite structures person. But I had an interesting conversation with someone who said he was one, at ORD the other day.
He confirmed what you say - you hit the skin with a 5 pound mallet and you'll break the mallet before you break the skin.
But he also said that while there was no apparent damage inside or outside, when you got to layer 4 or 5 (eg if there are 9 layers) you sometimes see microscopic mechanical changes from some kind of internal refraction which are not seen on the outer layers. Which takes us back to 'how would you know if the aircraft had been damaged if johnny honeycart or ecoli caterers smack the skin and don't report?' Was he talking out of his afterburner?

[World of Tweed]

PinkMan,

I'm no expert here but I remember asking the same thing. I was told, anectdotally, that the 787 was supposed to be having a "web" of electric magic filaments embedded in the layers which apparently will highlight any subcutaneous fractures or potential damage to an onboard system - most likely not accessible to the crew - hardly good for crew morale!

These would be in addition to any conductive elements re: lightning strike.

[barit1]

The straightforward systems approach would be to resign the honeywagon and his cousins to fail before the aeroplane does. Rather cheaper to fix it than Mr. Boeing's $multimillion flying machine.

(Strange thought: every time Boeing or Airbus sells a carbon-composite aircraft, can they also sell carbon offset credits?) :D

[FakePilot]

Sorry for the dumb question, but I'm curious and it's friday:

Can you patch composites with "tin"?

[Grunf]

Yes, if you want you can put two metal patches, one on the outside and one on the inside.

Cheers,

[McAero]

So the correct answer is a plaster. Easy :E

[tony jarrett]

Hi JOE 90 , could i ask you to mail me as i would like to ask for some imformation from your logbook on trident G-ARPO, cheers tony

[Volume]

Skilled glider repair shops do composite repair for over 40 years now, and they really do repair everything, up to a wing completely broken at the root. Doing your first loop in such an aircraft after finishing the repair is a little scary though...
In 10 years time it will be as comon to repair a plastic phantastic as it is to repair a tin can today. But I do not want to be the first operator to dent the Dreamliner...

[Beeline]

Titanium repair patches with hi-lok fasteners.

Problem like your bumper of your car is what happens when the impact damage spring backs leaving no evidence of damage but defects behind.

Im sure mr boeing has thought of that though.

[lomapaseo]

Problem like your bumper of your car is what happens when the impact damage spring backs leaving no evidence of damage but defects behind.

Im sure mr boeing has thought of that though.

As an example, I recall a Pan Am B747 engine that caused quite a stir when it got to the shop stinking to high heaven. When they took the nose spinner off they found a bird carcass neatly nested into the fan disk. Lots of questions at the time on how the bird got in and made a nest before dying when the plane flew off.

When they more closely examined the spinner they found that the fiberglass shell was cracked and full of blood spatters. It seems that the bird had caved in the spinner upong impact, cracked it and slipped inside as a blob before being centrifuged inside the face of the fan disk. The spinner than simply sprung back and closed up the crack.

[cappt]

From the overhead picture I can see at least 7 frames and 8 stringers damaged and this is from the outside, this fuselage is not going anywhere. Can the aft fuselage be de-mated from the center?

[Typhoon650]

Someone better tell the high performance boat guys their boats can't be repaired...they've only been doing it for 40 years.

[J.L.Seagull]

Actually, Boeing has already been thru this several times with different press releases, describing the process.

A 'bang' or contact with a foreign object that cannot be detected by a GVI is not a concern.

For minor damages detected by a GVI, an adhesive patch repair that takes a maximum of 1 hour to cure will see the airplane thru until the next C-chk.

At the next C-chk, or for major damages, a permanent repair scheme (similar to a traditional composite repair) has to be executed that takes about 24 hours, and is good for the life of the aircraft.

I'm just being lazy by not posting references, but anyone with access to the 787 SRM will be able to give references.

[bcgallacher]

Lomapaseo - your story about the PanAm engine spinner is a little unlikely as all the big engines have metal spinners. PanAm was a user of JT9s and all versions that I know of had metal spinners.

[TURIN]

At least one 787 operator has had a major attack of ramp rash this year. The catering truck punctured the fuselage below the aft door. An "L" shaped cutout repair was required. A specialist team from Boeing took considerably more time than 24hrs to complete.

[J.L.Seagull]

BCG... a lot of big engines use composite materials for their spinners... RR Trent 500, 700, 800 all do. Maybe to 900 too?

It also takes a lot more to damage a GE90 carbon fan blade than traditional metal blades.

It's actually a mindset problem, combined with a lack of industry experience.

TURIN: I've seen that kind of damage too on a 777. Approximately 10 foot long gash on the underside, below the R5 door. Took nearly a week to repair (including replacing a couple of frames!)

What really hurt though, was that that airframe had just 30hrs total! Sniff, sniff!!!

[Saint-Ex]

Of course it`s a simple matter to repair composte structures such as high performance yachts, racing cars, gliders but they are not subject to an 8psi differential.

[mustafagander]

I think the 8psi or so pressure load could be an advantage - high performance sailing craft have enormous problems with the flexing loads when they slam into a seaway especially working to windward. The flexing does the cores no good at all and disbonding is a grave danger for under designed structures. At least a pressurised hull would generally have no flexing stresses.

[aeromech3]

Mustafagander, we are talking commercial passenger aircraft here, they both flex, twist and suffer fatique through the pressurisation cycles during normal operation.
If ever you fly, on a B747 especially, you might even notice the effect this has looking along the cabin length.

[Chu Chu]

One of the things that typically makes a vehicle, vessel, etc. "high performance" is that the structure is engineered to be just strong enough and no stronger (and therefore no heavier than necessary). The loads in a pressurized aircraft fuselage come from different sources than those in other applications, but they aren't necessarily more critical.

[bcgallacher]

JL Seagull - read the post,PanAm were long gone before the Trent series were in service.

[A4]

All these comparisons to boats, cars etc are nonsense! If a repair fails/delaminates on a boat or a car then you stop, moan and get out. If a repair fails on an aircraft in the climb/cruise/descent then it's highly likely that the entire airframe will fail with a loss of all on board + possible ground fatalities.

Some perspective, please.

[DWS]

Copy of my # 242 on heathrow fire

perhaps as a starter

AERO - Boeing 787 from the Ground Up (http://www.boeing.com/commercial/aeromagazine/articles/qtr_4_06/article_04_2.html)

Boeing 787 maintenance manual - free eBooks download (http://www.gobookee.net/boeing-787-maintenance-manual/)



JAL Experience - Examine 787 CFRP Repair - Aviation Week Events on www.gobookee.net - free eBook download (http://www.gobookee.net/get_book.php?u=aHR0cDovL2V2ZW50cy5hdmlhdGlvbndlZWsuY29tL2h0b WwvbWFzMTIvV09SS1NIT1AlMjAzX0NPTVBPU0lURVNfSElST0tJX0ZVS1VZQ U1BLnBkZgpKQUwgRXhwZXJpZW5jZSAtIEV4YW1pbmUgNzg3IENGUlAgUmVwY WlyIC0gQXZpYXRpb24gV2VlayBFdmVudHM=)


Boeing Composite Airframe Damage Tolerance and
Service Experience
Allen J. Fawcett (ATF/DER) and Gary D. Oakes (ATF)
Boeing Commercial Airplanes
787 Program


found at

http://www.niar.wichita.edu/chicagow...0&%20Oakes.pdf (http://www.niar.wichita.edu/chicagoworkshop/Chicago%20Damage%20Tolerance%20Workshop%20-%20July%2019-21,%202006/Wednesday%20-%20Session%201%20Presentations/Boeing%20Transport%20Experience%20with%20Composite%20Damage% 20Tolerance%20&%20Maintenance%20-%20Fawcett%20&%20Oakes.pdf)

and

sort of covers the composite -front

In-situ composite repair builds on basics : CompositesWorld (http://www.compositesworld.com/articles/in-situ-composite-repair-builds-on-basics)

My point is there are many ways to repair and inspect major- minor damage.

However- the damage shown so far at Heathrow may well be above reasonable limits- cost- etc.- includinjg electrical- smoke damage - time- cost via insurance and no doubt a few hundred other issues not touched on here

787 and other composite model airplanes with major composite structure have been around for quite a while.

It is NOT like fixing your fiberglass corvette of the 60's and 70's, nor is the old story about epoxy fumes- lighting strikes- etc really applicable.

Hope this tamps down at least Some of the flip flapping

[Typhoon650]

A4,

You don't just get out and stop on a boat.
Fact is, there is really nothing terribly special or advanced with regards vacuum bagged/baked/pre preg composite structures anymore and there hasn't been for at least 20 years.
Repairs are simple, straightforward and will last many years in service.
Boats are an excellent representation of how well composites do, an 8psi differential is a relatively simple load to deal with- it's spread evenly over the entire structure.
Modern racing yachts have enormous high stress point loads entering the structure, like tension from chainplates, compression from masts and flexural loads from keels and appendages. The loads on large racing yachts would be as large as the loads on an airliner and peak loads I'm sure would be much higher. These yachts get extensively damaged quite frequently and repaired just as often.
But it's OK to not know much about a subject and dismiss what you think you know as all you need to know.

[lomapaseo]

Lomapaseo - your story about the PanAm engine spinner is a little unlikely as all the big engines have metal spinners. PanAm was a user of JT9s and all versions that I know of had metal spinners.

A fair challenge.

I'll await support from others either that or free beers if I'm wrong :)

OK the cap and mounting ring are metal

[Exup]

JT 9 spinner cap is definitely composite.

[Machaca]

Composite indeed (http://www.ntsb.gov/aviationquery/brief.aspx?ev_id=20001211X13284&key=1).

[grounded27]

[QUOTE][You don't just get out and stop on a boat.
Fact is, there is really nothing terribly special or advanced with regards vacuum bagged/baked/pre preg composite structures anymore and there hasn't been for at least 20 years.
Repairs are simple, straightforward and will last many years in service.
Boats are an excellent representation of how well composites do, an 8psi differential is a relatively simple load to deal with- it's spread evenly over the entire structure.
Modern racing yachts have enormous high stress point loads entering the structure, like tension from chainplates, compression from masts and flexural loads from keels and appendages. The loads on large racing yachts would be as large as the loads on an airliner and peak loads I'm sure would be much higher. These yachts get extensively damaged quite frequently and repaired just as often.
But it's OK to not know much about a subject and dismiss what you think you know as all you need to know./QUOTE]


You have got to be kidding, it is 8 lbs per square inch, calculate that by the seemingly 8ft by 4ft damage to the 787 I believe is in question? It will be an impossible task to patch this damage.

[A4]

Typhoon, with all due respect (despite your last sentence), YOU miss the point entirely. If the repaired hull of a boat/racing yacht subsequently fails it is unlikely to be fatal - inconvenient if you have to man the life rafts. Any subsequent failure of a repair in flight is highly likely to be instantaneously catastrophic to the aircraft i.e. in flight break up.

I confess I'm not a composites guru - but I do know that the 787 construction is at the cutting edge of the technology in COMMERCIAL aviation. I know the military has used it for years (decades) BUT the number of cycles that a military aircraft flies compared to a commercial aircraft does not even come close. So we are in uncharted territory w.r.t. historical knowledge of EXTENSIVE (i.e. very large fuselage sections) composite repair on high cycle commercial aircraft.

As someone who regularly straps an aircraft to his backside to earn a living, perhaps you can appreciate my concerns with this "new fangled" technology - I'm cautious by nature - not a bad trait in a pilot IMHO.

It would appear that the 787 has some issues with its electrical systems - with many commenting upon the decision to outsource so much and the consequential lack of oversight being a major factor. There have now been 4 or 5(?) smoke/fire events on the 787 which is unprecedented for a 1 year in service aircraft. That, perhaps, indicates that the development/testing/production/QA has not been as robust as it may have been - or Boeing have just been really unlucky. So forgive me for having nagging doubts (perhaps unfounded) about patching major structural "new" technology components.

It will be interesting to see what Boeings decision is regarding the ET 787. "Patch" it to reinforce (no pun intended) faith in the strength/integrity of the product or replace the entire rear section - "just in case"?

[cockney steve]

As I posted elsewhere...I agree with the sentiments that marine composites have a harder life than a composite aeroplane.

The fundamental problem a lot of people have,is understanding that Laminates do NOT need to be replaced as complete panels.
a "patch" can be laid-up in situ, or a part-panel "let in" to replace a damaged area and the finished repair has the same integrity as a piece that was all laid-up at the same time.

Anyone dismissing the danger of an "at sea" failure, may like to cast their mind back to Tony Bullimore's adventure, where the (metal) keel snapped off his (composite) yacht.

I'd venture that the loads imposed by a mast ~80 feet high, pulling a large yacht over to 45* + , with several tons of heavy keel counterbalancing it, in a sea of waves higher than a house, slamming the lot continuously.....is a greater loading than that on a pair of wings lifting a fuselage into the air.

Just gut-feeling, you understand....but try walking on the seafront on a stormy day and tell which hits the hardest.....gusts or spray?

[A4]

I hear what you say....and am starting to get a feel/idea that composite repairs are indeed very strong and no doubt yacht hulls/keels are subject to huge forces. However, when failure occurs, on a boat you don't have to worry about gravity. This is the point I'm driving at - the immediate aftermath of any failure.

[Sorry Dog]

Typhoon, with all due respect (despite your last sentence), YOU miss the point entirely. If the repaired hull of a boat/racing yacht subsequently fails it is unlikely to be fatal - inconvenient if you have to man the life rafts. Any subsequent failure of a repair in flight is highly likely to be instantaneously catastrophic to the aircraft i.e. in flight break up.

Not necessarily. I know there are quite a few boaters that have craft that go over 100 that would strongly disagree with you. Unfortunately, there have been example fatal accidents due to hull failure, and this is especially true of air entrapment hulls and pad vee hulls that are very sensitive to input and balance. Hitting the water at 100+ can sorta be hazardous to your health.

I kinda sense a little bit of snobbery here... try squeezing your nose and say "no boat patch kit couldn't possibly be adequate for my carbon nano-tube polymer aircraft."

No doubt composite repairs on the 78 are mission critical, but I think what others are trying to say is that use and repair of composites have many years of precedence in other high performance applications.

[A4]

SorryDog - you're obviously talking about high power speed boats? Yes I can fully appreciate that a hull failure at speed in one of those would be serious - my previous posts were referring to yachts of the sail variety. These speed boat crashes/failures are indeed spectacular but it's all over in an instant and only happens in one dimension which increases the survivability.

I don't understand your snobbery comment - there is none here. My concern is that the longevity of major fuselage repairs on HIGH CYCLE airframes is a relatively unknown quantity - and the effects of a failure at 500 knots let alone 100 are obvious.

[Denti]

Nevertheless composite airplanes have been around for more than 60 years now and there is quite a bit of experience with them. The flexing a high performance glider plane wing can withstand is impressive, in gusts you can see waveforms travelling through the wing and torsion during highspeed flight is quite severe. Happens nearly every flight and correctly repaired wings and fuselages have no performance issues at all, which is quite something considering that the normal operating envelope is +5,3g/-2,6g.

[mustafagander]

A4, we're close to the same page I think.

Pressurisation loads would help to stop "inwards flex" to which a yacht hull is terribly susceptible. As I see it, the loads would tend to be mainly in two dimensions and the hull would not have "in and out" loadings. Think about the loads in a multi flying a hull or close to it - think of cross beam stresses and attachment stresses, then slam into a wave and dump both hulls into green water, slowing to a couple of knots while the rig is doing 25Kt plus instantaneously.

When a hull fails at speed in, say, the Southern Ocean, it is not a simple ho hum hop into the life raft. You are very likely to die and quickly. Exposure will do for you within minutes in winter and tens of minutes in summer - lose the boat and you're screwed.

A little bio - I have been racing high performance multi hulls for decades and also have mega hours on big Boeings as a maintenance guy, flight engineer and pilot from B707 up to B744 so I really do know about aircraft and flexing.

[flyboyike]

Just use some Squadron white (or green) putty.