Unsuitable Maintenance
My most dangerous Concorde incident, airline politics, and important details that can get missed when tradition is brought up to date.
Introduction
The no-holds-barred, relentless quest for business efficiency: and flight safety. Bigger, cheaper, safer, (not nicer)? Have we reached the cliff edge without noticing?
Nuclear peace, exploding technology and runaway communication have driven overpopulation and social upheaval like there’s no tomorrow? Now there’s a thought! Perhaps we humans really are closer to that point than we like to accept. A new plague of biblical proportion and a rekindling of robber baron tradition (and its truly poor — in spirit, anyway), social networking to replace a treasure house of learning, and the rise of populism all say too late. It’s Yucatan reboot time, again. What creature will next inherit the opportunity to dominate the planet?
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The practical and safety-related craft of reliable piloting, and the engineering expertise that goes with it, require the same ethical approach: it’s called honesty. Today the competition/profit first priority makes this fundamental safety principle seem old fashioned, but you cannot cheat the laws of physics, thermodynamics, chemistry, or any other feature of the natural world. You can try, and you may get away with it, but that would be luck. It’s not the way to bet if you value a long life for yourself or those associated with your work in the uncompromising world of flight.
Many years ago, Lord King (Sir John as was) was given the mammoth task of first amalgamating two rather different state-owned airlines, and then presenting the result as an efficient business worthy of flotation on the choppy seas of public ownership. There was a lot to be done. Outrageous overstaffing had to be rectified, a combining and slimming of parallel specialisations, and so on. Sir John, backed by a peculiarly ambivalent Mrs Thatcher, worked at his task, convinced that a publicly-owned British Airways, representing Britain, should have Heathrow to itself, and continue to fly the flag. (That’s what Air France do, but under different conditions — not quite the same.)
Engineering support:
Military or civil, there is no flying person who does not have the greatest respect for those unrecognised many who devotedly look after the aircraft that the daring flyers’ lives depend on. Except for those who trust to fate this must apply to many multi-national colleagues. It has always struck me that the world at large, so awestruck by the super-human creatures that actually drive the plane (reputedly), has little concept of those behind the scenes who make it work — or especially of those who spent years slaving in a Monday to Friday drawing board and slide rule ‘do-it-again’ purgatory creating it.
When I was first allowed solo in the Concorde in 1985 we still had a system whereby a group of three Concorde hangar people would meet us on arrival at London — rather like the customs men who used to meet an early 1970s Jumbo arrival and carry out their bar paperwork to the tune of agreeable upper-deck sharpeners. But our Concorde hangar people were only interested in any foibles of our speedy machine; anything at all. This decade-long Concorde development tradition soon died out. ‘This Prima Donna has to be treated as another airliner’ was to be the new bus garage motto. ‘We’re now a grimly competitive bus company, not a bunch of formula one fairies.’ Nobody actually said this, but perhaps you get the idea.
The risk of anything not working
The complicated and largely novel Concorde did its job wonderfully well if everything worked, but even if the tiniest thing failed the implications and tactical rearrangement of the plan of campaign could easily and instantly become highly significant, and possibly very critical. ’Just like a fighter?’ Actually yes, in terms of the immediate things to be done simultaneously with a change of tactics. ‘But nothing ever happened, you all landed successfully for 25 years. What was so difficult?’ In fact there were many potential if apparently trivial failures that could significantly change the nature of a flight. They are sufficiently different in nature from subsonic flight to be left for future discussion. Other practitioners of hair-on-fire piloting are similarly reluctant to discuss such professional matters. There’s little supersonic tactical ground in common with the High Street experience.
The first thing I found out about the Concorde
In the early 1970s, between Concorde prototype first flights and the end of its development, I was present at a 747 assembly when our training manager, Phil Brentnall — an experienced, calm and wise 4-engined practitioner — told us about the current certification debate about Concorde emergency procedures, and the difficulties thus raised by certain traditional concerns.
Ditching? Forget it. No chance. Can’t disagree with that. Even Captain Sully might agree. But allowing the Concorde to do away with floating devices would not be fair: all competitors must abide by the same rules: so dinghies and slide/rafts were still in. I never did get to go in one of these for real, but we did have them.
The other problem was how to land without all three undercarriage legs not down and locked. Any unsafe leg would probably result in a landing too dangerous to countenance for passenger transport. There was an easy certification answer. ‘The whole system is beautifully designed, has a standby hydraulic system and a free-fall possibility which requires only gravity, and engine compressor air if really needed. What’s the problem?’ So some traditional pages did not appear — it will never happen. This seemed to be a new concept for British public transport airworthiness, and the prospect of all wheels satisfactorily down was assumed for convenience. It usually worked.
After what must have been the first major dismantling and putting together checks of the Concordes, after ten years of flying as an airliner, the first sign of something wrong with the undercarriage started to appear, first on one machine, then progressively on some of the others. This phenomenon was quite consistent, and clearly different from heretofore normal behaviour. And because, I suppose, the end result remained satisfactory, the strange behaviour, as far as we simple flying journeymen were concerned, was not explained, but assumed to be expected after such a major check. How much interest was taken in this engineering anomaly elsewhere I don’t know. ‘We’re not a research organisation. We’re now an airline business struggling for existence. Don’t rock the boat.’
I was to find out the engineering answer in due course, but first a technical explanation is necessary. Unfortunately I do not have the beautiful training diagrams of this machinery to hand, so will have to explain the Concorde shortening mechanism by words. Academically ‘woke’ trigger warning specialists should avert their gaze until the undercarriage leg is locked down with no extraneous warnings showing. All will then be well, and you can continue your button pressing aviating with confident, caring, consensual, non-judgmental and life-enhancing feelings.
Shortening lock behaviour, and what should happen
First of all, this device should be called a lengthening lock: it only features when a main leg is at full stretch i.e. down. But if your perspective is ground based the shortening function is of mysterious, remote and of airborne interest, and there is no locking required when the gear is up (shortened) — except for the normal up lock. I hope that is perfectly clear.
T
he Concorde main undercarriage leg lengthens as it moves from its up to its down position, achieved by simple geometry. The unfolding hinged link at the top of the leg, which achieves this increased length, snaps over-centre when it reaches the correct down position, forming a ‘locked knee,’ rigid top of the leg. Like the down-locking process elsewhere this final action is assisted only by a spring. Normally this locked knee situation occurs just before the down lock is indicated (traditional green light) after which hydraulic assistance for the lowering action is isolated. It also has to be mentioned that, so far, main gear locking down had occurred with the mildest of thumps as the down lock engaged and the extension process ceased: hardly noticeable — an affair of sophisticated taste and discretion.
A yellow shortening lock light, indicating that this top-of-the-leg link was not yet in its weight-bearing, on-the-ground lengthened position, used to go out just before the green gear down light came on — its spring alone ensuring that it jumped into its own, over-centre, locked position when close enough to the straight knee position.
What was different after the major check
The new situation was as follows. When the ‘wheel down’ green light came on, the shortening lock light stayed on. There was no logical reason for this. Then there was an almighty thump as the shortening lock light went out. Definitely different, but everything looks OK finally, so what’s your problem? I do not know how many other people were puzzled, and perhaps concerned, at this new behaviour, and pilots are not always closely associated with hangar politics, but the facts eventually emerged — quietly — to a few who were interested.
Apparently there are three hydraulic connections at the top of a Concorde main undercarriage leg, and it was possible to connect them incorrectly. The explanation for the new behaviour is now simple. The little hydraulic jack that pushed the shortening link out of its locked (lengthened) position, as an initial step in the wheels up process, was now inappropriately powered during the down process, and this link was prevented from clicking over into its locked knee position — until the main undercarriage down lock was made, green light on, and hydraulic pressure removed. The vertical jolt from a locked leg as the relieved shortening link on top snapped over centre into position on the top, jolting the leg length — just a bit but quickly — was novel, to say the least.
Simple evidence during our landing minus main gear down lock
G-BOAG showed the curious shortening lock symptoms, and it was this Concorde that gave us the additional down lock failure at Prestwick. No green light, and the look of the down lock telltale under the floor confirmed that this important lock in the telescopic strut was not made. The shortening lock light had stayed on until I put the undercarriage lever to off, as required for the free fall checklist. This light then went out because selector to ‘off’ means no hydraulics, and the top-of-the-leg device was permitted to take up its correct position, indicating that the leg was at least close to the down position.
Why did these different things happen?
Both these problems were caused by the same paperwork problem. Our failure to lock down, and the peculiar shortening lock behaviour were not connected directly, but were both a result of pages missing from the English maintenance manual (how to put the main undercarriage parts together after taking them apart). In connection with the serious down lock failure I heard the name Hispano Suiza mentioned, and the news that the current French instructions had not been translated, hence were missing from the English manual. I do not know the intricacies of this undercarriage design history, but what seems to be correct is that everything was intended to work wonderfully well, and reliably - when assembled as designed.
More recently I heard that the pages had been missing after an amendment session. This is a tedious job for somebody, and it’s easy to get confused with ‘replace, remove and destroy’ etc. When I rebuilt my car I used my Halfords torque wrench for even the smallest fixture when instructed by the Haynes Manual. It was worth it, but what do you do if the putting together pages are missing? Put all the pieces back where you think they came from, make sure there are none left over, tighten the whole thing up, and away you go. As good as new? Not always.
The proper procedure for putting the Hispano Suiza Concorde telescopic strut and its down lock gismo back together has an important intermediate check before tightening the whole thing up and sending the machine on its way. At finger-tight torque there is a feeler gauge test which proves that all the small parts you have replaced are in the right places, then you tighten the big nut on the end. If this page is missing what might the practical engineer do?
I later heard that the hydraulic connections on the top of the leg were mounted in an equilateral triangle fitting. Very elegant, but, as you will have already guessed, it fits beautifully when 60⁰ wrong. Was this the reason for the incorrect powering of the shortening lock? Was this true?
I’ve no idea? But I have to confess to some relatively inside gen because I was on the aircraft that demonstrated the down lock problem, and I was privileged to see the damaged bits on the engineering manager’s table. By now, all reassembled struts had been removed, checked and correctly reassembled. There had been more faulty examples currently carrying passengers: they did get fixed as a result - very quickly.
Is the modern industry getting safer, as well as cheaper? Take your pick. While both these advantages appear to be related today, what’s really happening? Current enthusiasts developing mini-Concordes should be careful not to abandon old-fashioned tradition in favour of marketing fame and fortune. Successful supersonic flight is still expensive, mistakes especially so. After the first, definitely the second development disaster, your exciting dream will be over, and the rest of us will not even have had the chance of another relatively safe supersonic ride.
The two fundamental reassembly deficiencies referred to in this essay do not accord with the engineering standards traditionally assumed for the safe flying of high performance modern aircraft: ask any military or research person. As a simple pilot my engineering training had finished with Meccano at about age thirteen, and I later followed the instructions in my Haynes Spitfire (Triumph /Herald) manual assiduously. But this was hobby engineering, no business pressures at all.
The apparent choice of Concorde hydraulic connections somehow had enabled the shortening lock unlock jack to be inappropriately powered during ‘down’ as well as ‘up’, and the Swiss watch precision down lock in the telescopic strut had missed the special feeler gauge check to prove that all the invisible and beautifully crafted collets were correctly positioned. Why were the necessary pages missing? First whispers said the problem started in France with a Hispano Suiza French document, with the relevant English translations missing. It’s possible, but what about the Check list of Pages that accompanies all amendment issues?
Who gets the blame? The toolbox people on the hangar floor? Unlikely, is my guess, but unless directly involved with what goes on in the corridors of power those involved with the direct practicalities of safe repetitive flying — and here both engineers and pilots live at the sharp if ethically simple end — have little involvement with the commercial and ethical priorities that influence and change an industry as a result of market forces; unseen and not of particular interest to those interested in the technical side of safe flying. Looking back, a lot of British Airways things changed between 1975 and 1997 with the long and difficult process of amalgamation, downsizing, economising, and all else that is necessary to combat the deadly enemy of competition. ‘Dirty Tricks’ (Gregory) is an unmissable read for anyone interested in changes of style in the corridors of power, painting a picture of the new priorities of a world-based society. The workers do their best, and one can only sympathise with those who have been persuaded to participate in unethical practices. Of course, readers will understand that this refers to customer service areas, not engineering, but aren’t we all in this together? Read the book.
Actually, not much has changed in terms of worldwide rich and poor, and an immensely unequal wealth distribution. It has ever been thus, of course, but it’s a different variety of humans and their beliefs and ethics who make up the new haves and have nots. Not long before I retired I remember going behind the hangars to pick up a Concorde (training flight I would guess) and immediately noticed that one engine gauge indicated a completely different primary nozzle position from the other three. There must be a reason for this and I mentioned it to the ground engineer who was present. His immediate response was ‘indication fault’. This was a novel approach to such an important gadget and a look outside showed that the nozzle was as indicated (did he know what a primary nozzle was?). The correct answer should have been ‘we moved it to check something. It will go to the right place when you start.’ But it was obvious that things had changed. Flyers and their technical support were no longer part of the same team.
A sign of the times I think, and quite unlike the dedicated expertise still shown in 1985 - before the hangars were swept clean by new brooms. If I appear to feel quite strongly about this engineering situation I do, and although the strange shortening lock behaviour was already evident on post major check aircraft the same down lock fault was rapidly discovered on another couple of recently reassembled struts. The point is that this one example nearly killed me, John Cook, Roger Bricknell, Tony Yule and Keith Barton — and our three trusting pitstop crew. It was an outside chance that this difficult situation occurred to a training crew and not a service flight on final approach - with little time and no options.
The Concorde worked wonderfully well if looked after, but a time-and-motion-pressurised garage is not the place to look after one. There’s still plenty of conjecture about the full story of the Air France disaster, even though the subject has been officially laid to rest. But the ‘how long will the Concorde continue to fly’ question should have been answered right there. It was time to stop, unfortunately. An excellent aeroplane, a masterpiece of Anglo-French cooperation with historical German aerodynamic design assistance; but too critical for the modern industry.