Author Topic: Vulcan Bottle failure  (Read 20793 times)

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Offline planenut

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Re: Vulcan Bottle failure
« Reply #15 on: October 05, 2015, 12:20:15 AM »
Where did this thread start? oh yes, the decision has been made, move on.
I said "no more passwords" and look what happened!

Offline Rover3500

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Re: Vulcan Bottle failure
« Reply #16 on: October 10, 2015, 12:53:33 AM »

http://www.caa.co.uk/aandocs/27038/27038000000.pdf

I'm curious why the Vulcan has such a (predicted) relatively  low airframe life expectancy.
These are said to be  strong aircraft..perhaps the designers understandably 'played safe' with  fatigue modelling as airframe  technology was less well understood in the 1960's.
It's disappointing that we don't have methods available  today that would allow us to predict more accurately  where failure on XH558 is likely to occur and what effect,if any  this might have on flight performance.

The RAF were granted an extension to the fatigue index of XH558 in 1986  to allow her to operate in the Vulcan display team until 1996. It seems unfortunate that  a similarly sensible decision can't be taken now to allow XH558 to fly until 2018 .

For comparison most of the Concorde fleet had around 25,000 hrs of service . A Boeing 747 airframe can easily achieve  100,000 hrs. and it's wings have plenty of 'flex' in them .  Vulcans 7500 hrs seems like nothing in comparison.
Similarly Rolls Royce designed the major components of the  1966  Olympus 593 engine to have a life of 25,000 hrs. It's hard to imagine a Vulcan Olympus covering anything like that.

The lifed components on the Vulcan airframe nearing their fatigue limit (from the caa report doc)  are the 'Rear  Spar bottom boom' & 'Front spar bottom boom & skin'. (both covered by modifications 2222 & 2429). The rest of the airframe has plenty of fatigue life left.

The problem for the Vulcan seems to be that Rolls Royce imposed a 'maximum installed life for each engine of 7 years'  in 2008 .

 Up to this limit (if operated properly) Rolls Royce determined that a risk of 'hazardous engine failure ' was less than 0.00001% per flying hour.

To go from 0.00001% to unacceptable risk because the engine is operated for 8, 9 or 10 years  seems a bit crazy to me.

Offline eddief

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Re: Vulcan Bottle failure
« Reply #17 on: October 10, 2015, 01:55:40 AM »
It's been a really long day here but I'll say it clear.

Anybody who knows me here will know my affection for 558 & my professional involvement in flight-safety.

I am of course, sad to know her days in the sky are numbered but everything comes to an end & I personally, feel this is about the right time.

She is a safe aeroplane, her team operates to the same standards as an airline & I have absolute confidence in it all - but given another few years & we would be into completely unknown areas in respect of fatigue; not good.  Aircraft don't forgive lapses of emotion - ever.  That's why cold-hearted professionals are given the task of deciding when the time has come & that time will come (in my opinion) around the middle of 2016; which is near enough 'now' to make no difference.

Enjoy her while you can...
985 posts on last forum - so I get the \'hallowed 1000\' for just 15 on this one (yippee!)

Offline Flipflopman

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Re: Vulcan Bottle failure
« Reply #18 on: October 11, 2015, 11:44:15 PM »
Oh dear. I fear that this is a typical case of a little knowledge being dangerous.

I've looked at this thread twice now and held off from replying, but I think it only fair that I refute some of your misinformed points.

Before I start, I note that there are plenty of figures and statistics contained within your posts, most unrelated to the specifics surrounding XH558's operation so can hopefully give you some more accurate figures to base your rants on.

I personally, am probably just as devastated as you are to see XH558 finish her flying career. I say probably because I have no idea as to your relationship with the aircraft or the history you have. We all have our stories. Personally, as a young lad being taken to airshows, watching the Vulcan display was the driving factor for me to join the Royal Air Force. It was the reason that long before restoration and return to the air became an option, I visited and donated to the aircraft and club. It was the reason that upon leaving the Air Force, I emailed the Trust and offered my services and became part of the restoration team.

Now, I should add at this point that not only am I no longer a member of the engineering team on XH558, but I have not been since October 2007 and the time of her first flight, but what I can hopefully offer is an educated opinion and some of my own experiences.

Firstly, at the very beginning of the restoration period it was only ever envisaged that there would be ten years of flight available to XH558. TVOC had at that point, thanks to David Walton and his foresight to buy the RAF spares inventory, 8 'zero timed' Olympus 201 engines, and these 'zero timed' engines were the whole reason that Rolls-Royce offered to give VTST their backing and support. When I use the term 'zero timed' that is to say that they had undergone a full overhaul at Rolls-Royce Ansty in September 1981 and even though they had previously accumulated many hours of running, were deemed fit by R-R to run for another overhaul cycle of 2000 hours.

Now, a condition of Rolls-Royce to offer their support to these engines and VTST, was that the engines would now be rated on a cyclic basis, in line with all of their civil fleet and in line with current practice and years of experience of engine wear life. As you make reference to the Concorde Olympus (Which are very different engines despite their common nomenclature) Which engines do you feel may have had a tougher life? 2000 hours of transatlantic cruising, or 2000 hours of Valley and Glen punishment with the engine being accelerated and decelerated thousands of times over the course of those 2000 hours?

Of those 8 engines, one was contested by R-R due to the fact that the history of silica bag changes could not be verified and following the first flights, one came back with a high debris count on the magnetic chip detectors leading to R-R putting that engine in quarantine. This meant that there were only 6 acceptable flight worthy engines available, cutting the available lifetime by a quarter. An incident with silica bags in the intake reduced the total available engine stock down to four, but thankfully some excellent negotiations meant that R-R agreed to accept and support the previous engines that had been questioned and took the total back up to six.

Of these six engines, as a former RAF Propulsion Engineer, as one of XH558's engine men and someone who currently manages engineering projects for Rolls-Royce's civil large engine fleet, the Olympus 201 is a very temperamental and unreliable engine with a long history of uncontained failures and many of which have led to the loss of the aircraft. Don't believe me, ask google. All of this is known, understood and managed by the aircrew, however, these should not be thought of as the carefree handling engines of today.

In short, XH558 has used almost all of the lifing that R-R are happy and prepared to underwrite, based upon not only the decades that she was in service, but also the decades of experience that has been gained since then and put that towards establishing a safe limit that has meant we have all got to witness her safely and without fear of escaping turbine discs.

Airframe life... Now, I'm realising that I'm already in the middle of War and Peace here, but again, this is another whopper of a topic. Basically, as you must clearly understand from all of the qualifications that you consider necessary to start your posts with, aircraft have not only a 'safe life' but a 'fatigue index' that is used to work out how long an airframe is safe to fly for. Well now, it won't surprise you to know that Avro, and later Hawker Siddeley had a Vulcan airframe on a test rig that stretched, twisted, pulled and pushed that airframe to simulate an entire flying career. Over that testing cycle, every single modification on every single Vulcan was developed on every single area that began to show problems. An airframe is normally lifed to 100FI with FI referring to Fatigue Index. 100FI relates to 100% of an aircraft's design life. XH558, through following all of the manufacturers repairs and modifications is now as far as I can tell you, far in excess of 240FI, or 240% of it's intended design life. As you can perhaps imagine, testing was stopped there, as nobody expected a vulcan to surpass that life. Of course, repairs and workarounds could be developed to keep 558 flying, but at what cost? Which airframe would you propose to build a testing rig around and how would you account for the corrosion and years which have taken their toll? Computer modelling you say? How would you account for the changes in 558 over the years structurally and how would you factor in the hidden degradation? Who would then sign that off and under what conditions and regulations?

Sadly, as much as it genuinely upsets me, the time is right for XH558 to make a graceful bow out and to say goodbye while still able to and while still able to carry out a farewell tour.

In light of the giant post I have just created, I'm going to stop there, but not before saying that I will happily answer any questions you may have and hopefully give you a few facts to work with as opposed to the fistful of half truths and best guesses you are currently bandying around as your own half cocked version of the truth. Undoubtedly, Sam Evans and Taff Stone can fill in any parts I have missed or which may have changed over the years, either way, I strongly feel that we should be grateful for the seven years of a flying Vulcan that we've just had, rather than being bitter about another couple of years that we would never have had anyway...


Best Regards,
Ron Evans,
Flipflopman.

Offline Rover3500

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Re: Vulcan Bottle failure
« Reply #19 on: October 12, 2015, 12:22:56 AM »
My 1/2p worth again...
I agree cold hard headed decisions have to be made based on good  science and engineering. Obviously the  discovery  of significant   cracks in critical and un-repairable airframe structures, erosion of turbine discs etc. should lead to an immediate grounding of XH558.

Without information on any such discoveries, the decision to end flight  does look a little like a 'back covering exercise' inspired  more by lawyers  than scientists and Engineers.
I don't blame the corporations involved for this - that's life in 2015.  I don't wish to be in any way  critical of the team behind XH558 - 8 years of flight  is an amazing achievement - the amount of work, dedication , skill and the jumping through of hoops set by the CIA  is mind boggling.

Fatigue failure  although inherently unpredictable always  presents itself as a crack long before failure occurs. When such  a crack   reaches a critical size (after the crack propagation life has expired )  these initial cracks  can  propagate through the structure and cause failure.   
 
By having comprehensive inspection measures in place to detect these initial cracks in critical components, aged aircraft are routinely  kept airworthy...I can't see why this cannot be done for Vulcan -  the maintenance regime seems too hung up on flying hours rather than being guided by  evaluation of the condition of the aircraft.

It has been said by the trust that is it ' knowing where to look for any possible failure will become gradually more difficult'.  Well surely they should look at the weakest links at the front/rear wing spars (in the case of the airframe) which is the most heavily stressed wing component.

 If this (and the other critical high stress areas)  can be given a clean bill of health by visual inspection and possibly more advanced  non destructive testing methods such as  ultrasound ,  I  can't see why airframe fatigue has to be a big show stopper.
Andrew Edmondson described the rear spars as being in 'fantastic condition' during the last major service so it would seem unlikely their condition is in doubt. 

Much emphasis is placed on the  Avro airframe fatigue test - an unmodified airframe that had a series of estimated loads applied to failure after which a 'best guess'  safety factor was applied to determine allowable fatigue life. My view is that after XH558's  50 years of mixed use  a  common sense approach should be used and the life of XH558's airframe determined by inspection  with the fatigue limits used as a guide only.

 

Offline Flipflopman

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Re: Vulcan Bottle failure
« Reply #20 on: October 12, 2015, 12:36:46 AM »
Rover 3500,

It is abundantly clear that you have absolutely no experience or understanding whatsoever with regard to Aircraft Maintenance and Engineering, the inspection and overhaul frequencies of the work and costs involved or the legislation required to comply with such. Consequently I feel that any attempts to convince you otherwise would be absolutely futile and a waste of both of our time.

I'll instead bid you goodnight but leave you with the reassurance that the safety of UK air travel is thankfully in much safer and better informed hands than your own.


Cheers,
Flipflopman.

Offline Rover3500

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Re: Vulcan Bottle failure
« Reply #21 on: October 12, 2015, 02:22:02 AM »
'Flipflopman',

Well that put me in my place!. What's wrong with saying 'no I don't agree with you..but this is how it is...'

Silly me I thought this was an 'Engineering' forum -  free for anyone to ask  tecky questions or  express views, however ridiculous and  have them contradicted, provoke debate,  learn things from those in the know . That's generally how it works.

Nothing about sly personal abuse from people who should know better

Yes I only have a little knowledge of XH558 except the snippets on the website. 
A project like this brings up millions of 'what if' and why  type questions that drive you mad. You want to know the rationale behind the decisions....

I thought my background   was relevant from where i'm coming from ... but sorry for bringing this up.
I suspect a lot of followers of Vulcan  know enough about engineering  to be intrigued and fascinated by what's under the skin of  XH558..then you realise how complex it is and how little you really do know!.
I did some  work years ago installing the condition monitoring equipment on the    RB211 gas turbines at Easington  but that was really nothing compared to the problems faced with managing an aged fighter bomber.

So that's why I came here to find answers (clumsily it seems)  from those  that have worked with XH558!.

The new role seems to be as a sort of Engineering recruitment role which I think is great for the industry which is too often seen  as boring and for 'geeks'. 

I have always said that I am a great admirer of the people that put XH558 back in the air.
They are all true British heroes.  For those  that put all the hard work in and us watching, 10 years of flight would have been an extraordinary achievement  but I know it wasn't to be.
8 years is still beyond expectations.

Over and out.


Regards
Ken Moore



Offline dee

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Re: Vulcan Bottle failure
« Reply #22 on: October 12, 2015, 08:43:16 AM »
Well after reading Flipflops in depth piece i guess ive just been selfish in wanting my Vulcan to fly for more years. Not going to apologise for that, shes been a  massive part of my life for so long now.
  Ive made some fantastic friends and met so many wonderful people. All the ground crew ive met have  always made me feel welcome. Because of this club and Sam Evans i even got to get my hands on her to help keep her clean!!.These memories will stay with me always. But yea i know now its time to say goodbye to this stage in her life.. Safety always should come first. 

Thanks for the memories
That huge triangle against the sky like some monstrous angel trailing dark clouds of glory

Offline Mayfly

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Re: Vulcan Bottle failure
« Reply #23 on: October 12, 2015, 08:49:54 AM »
Not selfish Dee simply leading with your heart. I too would love to see 558 go on forever but if those who bear the brunt of responsibility decide it's time to let her go then so be it.

Good to see you are still alive and kicking Ron.

Offline Gareth

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Re: Vulcan Bottle failure
« Reply #24 on: October 12, 2015, 10:45:43 AM »
Great explanation from Flipflop man, and completely justifies the decision to me.

The other aspect that nobody has mentioned, which is essential before any flying can happen, is INSURANCE!  It must cost a fortune to insure a 50yr old ex military, complex jet, to fly at displays.


Offline brains_mt

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Re: Vulcan Bottle failure
« Reply #25 on: October 12, 2015, 11:02:33 AM »
Ron! Delighted to see you posting after all this time ;D Hope the family ! is well and thriving  ;D

I think that if there is any doubt in anyone's mind ever then the time has come. Safety must always come first. This is especially true for people who are in the position of having to sign off the aircraft as safe to fly. I wouldn't want to be in their position for all the tea in China.

We've had a ball and we will always treasure the time we've had together with XH558.
Ex Club Co-Chair
Worked flat out to give XH558 as long a life as possible! Hoping for a positive future.
3601 posts on previous Forum

Offline Paddy Langdown

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Re: Vulcan Bottle failure
« Reply #26 on: October 12, 2015, 01:17:18 PM »
Great explanation from Flipflop man, and completely justifies the decision to me.

The other aspect that nobody has mentioned, which is essential before any flying can happen, is INSURANCE!  It must cost a fortune to insure a 50yr old ex military, complex jet, to fly at displays.

£183,750 pa was the latest figure I was given - I don't know if there is a No Claims Bonus!

Offline Wizzy

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Re: Vulcan Bottle failure
« Reply #27 on: October 12, 2015, 11:13:32 PM »
Great to see you posting again Ron, and thank you for such a reasoned (as always!) post - that, more than any other explanation I've read, has convinced me that sadly, the time is right for 558 to retire.

Seeing you posting has brought things full circle, and takes me back to the exciting days of the restoration, the hangar cams, and regular updates from the team working on 558.  Such a shame all that has been lost over several changes to the forum software.
Two things are infinite: the universe and human stupidity, and I'm not sure about the universe
  Albert Einstein

Offline Mattk303

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Re: Vulcan Bottle failure
« Reply #28 on: October 12, 2015, 11:43:41 PM »
Great explanation from Flipflop man, and completely justifies the decision to me.

The other aspect that nobody has mentioned, which is essential before any flying can happen, is INSURANCE!  It must cost a fortune to insure a 50yr old ex military, complex jet, to fly at displays.

£183,750 pa was the latest figure I was given - I don't know if there is a No Claims Bonus!

Really? costs more to insure a 17y old on a Fiesta!

Offline Flipflopman

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Re: Vulcan Bottle failure
« Reply #29 on: October 13, 2015, 08:44:05 PM »
Thanks for the kind words everyone. I'm really good thank you, but definitely more of a lurker nowadays!!

As I've said, on a personal level, I really am genuinely gutted to know that 558 has finally reached the end of her 'second life' but feel really proud and pleased to have been even a small part in helping her get there in the first place. As an engineer though, I understand the reasons why and can support those decisions.

It's a very emotive subject and while I can understand the depth of the feeling towards wanting to see 558 remain in the air, that has to be weighed against the reality of the situation. I certainly don't understand all of the anger toward the Authorities or indeed toward the Trust and I definitely don't understand what certain parties hope to achieve with their anger.

I've got all the time in the world for genuine questions and requests for information, as anyone who remembers my posts from the old forums, but can't quite extend the same level of patience when opinions and misleading statements are repeatedly stated as fact. Unfortunately, it appears that among some posters, not only here, but across most of the aviation forums, there is a depth of feeling and an anger bubbling away that all of the hours in the day spent in replying wouldn't fix!  ;D

Not that it would make much difference anyway!!  ;D


Cheers all,
Flipflopman