B787 repair question
Joined: Jan 2012
Posts: 159
Likes: 0
From: Holding at DESDI
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!!!
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!!!
Joined: Jun 2001
Aviation Qualifications: ATPL
Posts: 1,187
Likes: 59
From: OZ
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.
Joined: May 2011
Aviation Qualifications: LAME
Posts: 237
Likes: 7
From: Surrey UK
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.
If ever you fly, on a B747 especially, you might even notice the effect this has looking along the cabin length.
Joined: Feb 2009
Posts: 2,824
Likes: 110
From: Virginia
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.
Ut Sementem Feeceris
Joined: Jul 1999
Aviation Qualifications: ATPL
Posts: 4,793
Likes: 2,317
From: UK
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.
Some perspective, please.
Joined: Jul 2013
Posts: 61
Likes: 0
From: redmond
re repair
Copy of my # 242 on heathrow fire
perhaps as a starter
AERO - Boeing 787 from the Ground Up
Boeing 787 maintenance manual - free eBooks download
JAL Experience - Examine 787 CFRP Repair - Aviation Week Events on www.gobookee.net - free eBook download
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
and
sort of covers the composite -front
In-situ composite repair builds on basics : CompositesWorld
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
perhaps as a starter
AERO - Boeing 787 from the Ground Up
Boeing 787 maintenance manual - free eBooks download
JAL Experience - Examine 787 CFRP Repair - Aviation Week Events on www.gobookee.net - free eBook download
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
and
sort of covers the composite -front
In-situ composite repair builds on basics : CompositesWorld
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
Joined: Jul 2011
Posts: 140
Likes: 0
From: FG central
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.
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.
Joined: Mar 2002
Posts: 4,569
Likes: 1
From: Florida
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.
I'll await support from others either that or free beers if I'm wrong
OK the cap and mounting ring are metal
Last edited by lomapaseo; 14th July 2013 at 23:49.
Joined: Jul 2007
Posts: 377
Likes: 0
From: My Stringy Brane
Joined: Sep 2010
Posts: 1,339
Likes: 0
From: earth
Typhoon650
[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.
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.
Ut Sementem Feeceris
Joined: Jul 1999
Aviation Qualifications: ATPL
Posts: 4,793
Likes: 2,317
From: UK
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"?
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"?
Joined: Jan 2008
Posts: 1,191
Likes: 0
From: lancs.UK
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?
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?
Ut Sementem Feeceris
Joined: Jul 1999
Aviation Qualifications: ATPL
Posts: 4,793
Likes: 2,317
From: UK
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.
Joined: Jul 2013
Posts: 99
Likes: 0
From: Mosquitoville
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 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.
Ut Sementem Feeceris
Joined: Jul 1999
Aviation Qualifications: ATPL
Posts: 4,793
Likes: 2,317
From: UK
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.
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.
Last edited by A4; 16th July 2013 at 07:59.
Joined: Mar 2001
Posts: 4,563
Likes: 35
From: I wouldn't know.
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.
Joined: Jun 2001
Aviation Qualifications: ATPL
Posts: 1,187
Likes: 59
From: OZ
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.
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.