Posts about: "Corrosion" [Posts: 10 Pages: 1]

This thread is worth of cutting and pasting all the posts to make a book.

Is it true that the airframs had very little corrosion because during flight they were heated enough that any moisture literaly boiled off.

Does anyone have a photo of the inside of the baggage hold.

I've been wondering about that too.... just looking for an easy way to do a "copy and save" of an entire thread.
Any ideas?
It would need some editing afterwards, to bring the various sub-subjects together.

Quite true... it was a pleasant surprise during the major overhauls. People like M2dude can no doubt tell you far more about that.

It would probably have been a major factor in extending the service life, if other things hadn't put an end to that in 2003.

Even if the moisture did not literally "boil off", most of it evaporated, with structural temperatures up to 100\xb0C in many places, as against the -40\xb0C and less in some subsonic aircraft.

The forward or the back one?
Neither look very fascinating.
For the back one just imagine a short stretch of cabin without any seats or fittings or windows. On Delta-Golf at Brooklands and Alpha-Echo at Barbados, they're now used as a sort of small "entry hall" for the visitors.

CJ

atakacs ,

Opinions and remarks like yours really belong on forums like "SCG" or the comments columns of tabloids....

But I'll try to answer you.

The aircraft were "decommissioned".
That means that they were fully prepared as public museum exhibits, rather than being "mothballed", ready to be put back into service.
The purpose was not to make sure they would never fly again, it was to make sure they were safe for the public to visit.
That included draining all fuel, hydraulic liquid, etc.
That meant removing all pyrotechnics, like those in the RAT.
That implied venting and/or removing all high-pressure vessels, such as the emergency slides, fire bottles, oxygen systems, nitrogen tanks.
In the case of the BA aircraft, it also meant removing the electric ground power connections, to avoid incompetent amateurs trying to put ground power back on the aircraft, and start a fire.

Most of these things could have been rectified quite easily. But there was no intent to ever fly any of these aircraft again, so there was no effort made to "mothball" the aircraft, which would have been done quite differently, such as inerting some of the systems, dropping all of the engines, etc. and, far more importantly, keep a maintenance structure in place, not allow public access to any of the aircraft, etc.

Once Airbus relinquished the Type Certificate, that was the end.

Nice one...
You clearly have no idea what that would have been involved.
Just the spares alone... most of them are "lifed", and would regularly need to be either retested and requalified, or would have to be binned and replaced.

Quite what are you talking about here? No airframes were "recklessly butchered", unless you're talking about Fox-Delta, which was not really worth saving because of serious corrosion.

CJ

Interesting & nostalgic thread. Nice to see this monumental aviation achievement still generates such passion...

In case it's of interest (and suitable health warning as the memory fades)...

The heat did evaporate water vapour in the airframe - reducing corrosion. I remember when the 5 BA aircraft were returned to service, after the post-accident mods, their weight and balance certificates were prepared and found to be out by (IIRC) more than a tonne. This represented water in the airframe present after a year on the ground, and was gone again after a couple hours of supercruise on return to service. Back to the weighbridge for new W&B Certificates....

Vortex lift caused buffet which felt very similar to a conventional wing's stall/low speed buffet. At landing weights (I hate the trend of using the term "mass": weight is a force, mass is not!) you felt the buffet start as you reduced speed (CAS: Vc) to about 250kts. It was handy as a reminder that you should select visor down / nose to five below 250kts (the recommendation was as you slowed through 270kts, but latterly we were in the habit of holding at 250kts nose/visor up - I think TCAS was quoted as a backup to the more limited visibility in that config). At takeoff weights, the buffet went at more like 270kts accelerating. So I'm pretty sure there was no vortex lift at AoA > 7 degrees (250kts at LW).

Recommended subsonic cruise at MTOW was F260 / M0.95 which was equal to Vmo of 400kts (CAS). It was best cruise because Vc=400kts was also min drag at MTOW. F280 meant a slightly more draggy speed of 384kts, but some preferred it because when cleared to climb & accelerate supersonic (the official expression was "go for it") it gave you a bit of slack against Vmo when eng put the reheats in. But we tended to ignore the overspeed warning anyway: it was supposed to go really really fast...

We never flew with visor down and nose up unless it was bust - that config was only used during pushback (except one captain who always thought it looked better visor up....). Visor down max Vc was 325kts/M0.8 so it would limit subsonic cruise, and besides it made a racket like that.

It was a beaut in x-winds - a total lack of yaw-roll couple meant you just straightened the 'plane up with rudder and carried on into the flare as normal. No roll to counteract, and the sideways "lift" created by the rudder deflection on the fin pretty much equalled the x-wind drift. Nice.

Wind limits were Crosswind 30kts (15kts contaminated or autoland), Headwind for autoland 25kts (or manual "reduced noise" approach: that's a technical way we used to reduce the noise footprint down to 800' by flying at 190kts then reducing to a target speed of Vref+7kts at that point). Tailwind 10kts. All these limits were, of course, subject to "on the day" performance limits calculated at the time. I seem to remember there was an over-arching limit of 6000' on r/w length, subject again to "on the day" performance limits. OK, I cheated on this paragraph and dug out FM Vol 2a.

There were loads of other limitations which were, by and large, more "esoteric" than a conventional airliner and which had to be learned for the conversion course. It really made the head hurt, and would have been impossible without a big loverrly picture of the beast on the wall chucking out yellow smoke and making noise. Even a static picture of her seemed to make noise...

No one who flew it could really believe their luck, but one thing for sure is "they don't build them like that any more"...

Ahhhhhhhhhhhhhh..........

Mike-Bracknell
It is not nonsense, and you are quite at liberty to post here. Wow, that's still quite a question though Mike. There are two TECHNICAL issues that overshadow all others, namely airframe corrosion and hydraulic system deterioration. Unfortunately none of the BA aircraft were stored inside from the outset, so we have a real issue here as far as corrosion goes, plus all the hydraulic systems were drained, resulting in seal drying out and probable moisture ingress into the 3 systems. But given sufficient funds (and assuming you find an organisation to take over design responsibility from Airbus; ironic when you consider that without Concorde there would almost certainly have been no such organisation ) there is still no technical reason why the problems (and there are dozens of other problems to consider) could not be overcome, the money side of things is another matter
Looking first at the French fleet, the main candidate for restoration to flight status would be F-BTSD at Le Bourget. Not only has this aircraft been lovingly cared for and stored INSIDE, but the aircraft has had several systems (including the Green hydraulic system) powered and reservoirs not drained.
The British story is less clear; G-BOAA in East Fortune was effectively killed when the wings were cut off for transportation, so that one is out of the question. G-BOAB, the last and only Concorde at LHR has been left to rot outside, in fact holes were even drill in the fuselage to drain water, so this one is a no no too. G-BOAC at Manchester, now the oldest surviving production aircraft was initially stored outside, but now resides in a purpose built exhibition 'hangar'. Now she COULD be a potential candidate for consideration; when I last saw her just over a year ago she was absolutely pristine; a testament to the team that have been caring for her there. G-BOAD, stored next to the USS Intrepid in New York, we can probably forget, due to having been exposed to 7 years worth of salt water corrosion from the Hudson River. (Also, while she was temporarily stored in New Jersey a couple of years ago, some IDIOT in a truck bent the whole nose section when he hit her. The radome was smashed (replaced with a rather clever fibreglass fabrication) and the nose straightened with a blow-torch and hammer (I am not joking!!). G-BOAE at Grantley Adams airport in Barbados has been stored under cover for much of the time; provided she has not suffered too much from the wam damp atmosphere of Barbados, well she could be a potential candiitate too. G-BOAF in Filton, well PROVIDED she is still OK after her 'removal from public view' experience could also be a potential candidate also. And finally, G-BOAG in Seattle; well she had been left outside, right next to a highway (and close to a truck stop too). She did not look too good the last time I saw her; the undercarriage barrels werer all brown and discoloured and the paintwork was completely dull and matte. (She had a new paint job not too long before retirement too). So out of the 'BA Seven', I PERSONALLY would go for G-BOAF, G-BOAC or G-BOAG.
As I have said often here before, it is EXTREMELY unlikely that what you, Mike, suggest will ever happen, but in spite of what others might say, IT IS NOT IMPOSSIBLE. My own gut feeling is a resounding 'no', but I could be wrong, . (And NO ONE would be happier than I if I am wrong; I was with the BA aircraft through construction, flight testing and the entire service life with BA).
As for the cost? It really is a case of 'how long is a piece of string', but for 2 aircraft we could be looking in excess of $100 or more, who knows?
But as the Everly Brothers used to sing 'All I have to do is dream.'
Keep posting Mike.

Dude .

I would say that the SR-71, and the Tu-144, are in a way honorary members of the Concorde family, so I don't mind if they fly into the discussion every now and then.

The full list of names (up to 2002) for both BA and AF can be found in "The Concorde Story" by Chris Orlebar. For BA, a quick count shows about 170 names. That book also mentions, that the maximum number of crews qualified at any one time was 28, in 1980, and that the average was about 20 crews.

Photos can lie.... or rather, they are rarely close-up enough to show clearly where corrosion has set in.

As an example, F-BVFC at Toulouse, which was the last one to remain at least taxyable, now has some patches of corrosion starting to show, when you know where to look. Not to mention the nasty smell of damp and mould in the cockpit which bodes no good for what's going on underneath the floor.

And even F-BTSD, kept "live" to some extent at Le Bourget, leaks some hydraulic fluid (like all Concordes did on the ground), so it's easy to imagine the dried-out hydraulic and fuel seals on the other museum aircraft.




And yes, that's kitty litter...
The composite material of the floor and the hydraulic fluid don't agree too well.

I'll leave M2dude to answer that one.

CJ

islander539 ,
We ARE concerned, actually, and for the moment I don't think there is another thread on PPRuNe dealing with it.

I quote from your link:

"Mark Stewart, from Airbus, said: ....
"But the aircraft will return to its outdoor exhibition space sometime in the spring, and remain there until it moves to a new home.""

While the maintenance was indeed due, this seems to be an outright lie, so far.
After the maintenance, which will mainly consists of removing insulation that acts as a sponge for humidity, causing mould and corrosion, the aircraft is to be 'cocooned' (read: taped-off and sealed),and will be parked outside until the 'Concorde Trust' comes up with the money for a permanent museum.

Tough for the people who lost their job, deeply disheartening for the many volunteers who put their time in to show the aircraft to the public.

And a loss to us all... Alpha Fox at Filton was one of the excellent exhibits in the UK (been there, know the people concerned...).

CJ

This statement has been sent to Heritage Concorde by Airbus in the UK!

It's been place on my site, but I have also placed it on here so as many as possible will get a chance to read it.

Steve



\x93I am sure you will receive a lot of feedback regarding the aircraft and the maintenance work that needs to be performed. In the end, however, it comes down to one key point: the owner of the aircraft, British Airways, inspected its property, and determined that while the plane was in relatively good shape, these repairs are required. As such, the maintenance and preservation work will occur. I am sure you can agree, if the maintenance and repair did not occur, the plane would only degrade further.
Reference your source\x92s comments below:

• Airbus at Filton, and its predecessor companies, have maintained aircraft for many years and have a highly trained and skilled workforce who understand aircraft and maintenance programs
• We have performed a visual inspection of the airframe each week since the aircraft arrived and latterly had become concerned over indications of corrosion (please do not refer to this as rust) such as blistering and cracking.
• The \x93holes in the fuselage\x94 were certainly not created for TV. Our job is to maintain the aircraft, not damage it. These holes are in fact the result of corrosion in some of the lower belly panels which have been further exposed as maintenance/preparation begins. The hole in the leading edge is old damage that has been temporarily and repeatedly patched continuously over the years. We are now performing a more permanent fix.
• There are 7 windows leaking in total, including one on the flight deck which must be resealed to prevent cracking. The failure to repair leaks will present a huge risk, especially during the winter period, as window glazings can crack due to the expansion of water as it freezes, and there are very few replacements available. \x93

..... not convinced that theory's true.....

The PFCUs will offer a lot of damping, even while unpressurised. I've never seen a control surface 'slam' side to side on a hydraulically powered aircraft for tis reason.

The cause of the rudder failure was internal corrosion brought about by a mod which added a fillet to the trailing edge.

I suggest the surface winds were a red herring.

After about a week of 3-hour nights (not much on the telly) I have finally got to the end of this thread. Let me echo others in praising the patience and technical openness of the main engineering contributors, along with the excellent recollections of the pilots, cabin staff and many others.

I am afraid I have only been on Concorde around a dozen times, and as I live a few miles from Duxford, you'll probably guess that's 101 now in Hangar 1. Standing in the cabin I can only imagine the experience of actually flying in her, but you guys have certainly bought her back to life in my mind at least.

While reading the thread I came up with many questions (around ten or so) and these have been answered in later exchanges on the thread, however I do have a few left over:

1. The speed freak in me always wants to know "how fast"? Notwithstanding the principles outlined on p.55 by CliveL and M2Dude, if the intake system were somehow made "more leaky" and reheat were applied, in theory at least, how much more thrust could the 4 engines produce, in "ideal" conditions (I saw somewhere that -80C had been encountered)? If you then extrapolate the drag, what sort of peak Mach number might be attainable in short bursts (ignoring for now the detrimental effect on the airframe?)

2. There was a discussion or two of the (highly theoretical, expensive and unlikely) prospect of restoring one of the airframes back to flight around p22. However I don't think I saw 101 or 102 mentioned in any of these discussions, are these even further 'gone' (101 having sat outside for 20 years)? On the other hand, would the lack of sponge-like insulation mean less corrosion might have set in?

3. Again on p.55 there is mention of (naff) paint schemes and their bad effect on skin temperature. Was the paint on Concorde specifically chosen to radiate infrared (for example) to help cooling? The SR-71 (which I also visit at Duxford regularly - how lucky am I!) of course is matt black, which presumably radiates even better? When the airframe attained thermal equilibrium at the top of the cruise, what were the relative contributions to cooling of: radiation, cold uncompressed air passing over parts of the skin, the internal aircon (cooling from the inside), etc?

4. M2Dude referred a couple of times to robbing spares from other airframes. Spares that may have been 5-8 years old? What sort of testing regime must these spare parts go through to ensure they are still fit for flight? Is it labour-intensive?


If I can opine (at the risk of having M2Dude chastise me if he still reads this - as I am not staff) the computer he mentioned on page 37 sounds to me very much like a "bit slice" computer. These were typically constructed from discrete logic and quite often had very long words - 64 or 128 bits. I only ever saw one of these in my 30-year career in computing, a rare beast indeed. And yes I remember that Mil Spec TTL - back in the day I used to pop the lid off the ceramic packages and you can look at the gates, and even watch the silicon glow if you apply a bit too much Vcc! But I digress.

Thanks again for a fascinating thread.