Nimrod crash in Afghanistan Tech/Info/Discussion (NOT condolences)
Ed, Tuc,
I may have this wrong, but my take on your posts above would be:
It is usual to consider multiple failures in similar areas - hence the point of zonal anaylsis to look at issues that a straightforward functional analysis of failure modes might miss (i.e. a fuel system functional analysis might not consider consequential failures in a flight control system that is in its proximity etc.). This is especially relevant for the cascade failure modes that Tuc points out where you could have a situation where a fuel leak (e.g. prob 10-3) might saturate a theoretical flight control system component and make an aircraft crash. This would be a cascade failure where one not unlikely event (10-3) would cause a definate catastrophic event & hence wouldn't be allowed (though of course no flight control system would ever be designed that was susceptable to such a single point failure). This situation is similar I think to the "Nimrod hot pipe issue" in that fuel spilling on a 400C pipe will ALWAYS cause a fire and is therefore not acceptable.
Edset is right however that you wouldn't normally rule out combinations of events where the cumulative probabilities are infact low, but Tuc is right in that you should consider them. In the electrical spark scenario, you can say, e.g that prob of a electrical spark fault is say 10-4. Now this can't be allowed in a fuel tank where volatile vapours are very likely, but in a bay where the prob of a fuel leak is 10-3 this potentially would be allowed as the cumulative probability would be 10-7. It is worth noting that 10-7 would be well into the broadly acceptable category so the risk wouldn't even need to be reduced to ALARP - it already exceeds the acceptable risk threshold.
I've made the probabilities up - they are only to show the principle of cumulative probability. The risks of electrical 'sparks' in a fuel tank (TWA800 etc.) should not be confused with those in a normally benign environment.
I may have this wrong, but my take on your posts above would be:
It is usual to consider multiple failures in similar areas - hence the point of zonal anaylsis to look at issues that a straightforward functional analysis of failure modes might miss (i.e. a fuel system functional analysis might not consider consequential failures in a flight control system that is in its proximity etc.). This is especially relevant for the cascade failure modes that Tuc points out where you could have a situation where a fuel leak (e.g. prob 10-3) might saturate a theoretical flight control system component and make an aircraft crash. This would be a cascade failure where one not unlikely event (10-3) would cause a definate catastrophic event & hence wouldn't be allowed (though of course no flight control system would ever be designed that was susceptable to such a single point failure). This situation is similar I think to the "Nimrod hot pipe issue" in that fuel spilling on a 400C pipe will ALWAYS cause a fire and is therefore not acceptable.
Edset is right however that you wouldn't normally rule out combinations of events where the cumulative probabilities are infact low, but Tuc is right in that you should consider them. In the electrical spark scenario, you can say, e.g that prob of a electrical spark fault is say 10-4. Now this can't be allowed in a fuel tank where volatile vapours are very likely, but in a bay where the prob of a fuel leak is 10-3 this potentially would be allowed as the cumulative probability would be 10-7. It is worth noting that 10-7 would be well into the broadly acceptable category so the risk wouldn't even need to be reduced to ALARP - it already exceeds the acceptable risk threshold.
I've made the probabilities up - they are only to show the principle of cumulative probability. The risks of electrical 'sparks' in a fuel tank (TWA800 etc.) should not be confused with those in a normally benign environment.
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JFZ90,
Not necessarily. If you consider the EXAMPLE in 00-56 (because it is only an example although many projects followed it, and from Iss 2), then a Catastrophic event with a probability of 10-7 would be a Class A risk.
One has to be careful in considering the overall aircraft target versus individual system / hazard targets.
sw
It is worth noting that 10-7 would be well into the broadly acceptable category so the risk wouldn't even need to be reduced to ALARP - it already exceeds the acceptable risk threshold.
One has to be careful in considering the overall aircraft target versus individual system / hazard targets.
sw
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I stepped out of this for a little while, for a few reasons, some is way over my head with techie terms, sat and watched for a while but mainly because I had a few days away, up at ISK.
One thing which I failed to see on here is the idea that while the fleet has continued to fly a massive amount of checks have been performed on the fleet since the accident and again since the inquest, also throughout the time between.
I'm sure, okay scratch that, I know, there are a lot of checks being made to attempt to identify possible faults and to remedy those faults. That while it may be perceived as a risk to continue to fly, the attitude at ISK is anything but irresponsible to the crews safety, a great deal of measures have been put in place.
Had it not been for the loss of 230, the majority of these potential flaws and even obvious design flaws, would not have come to light. The Nimrod is probably the safest now than it has ever been as it is constantly being checked and double checked.
As simple as this may sound the majority of documents which are quoted, past investigations which have taken place, majority of the techie nature means nothing to me compared to the fact that the fleet is being scrutinised and examined with the intention of keeping her crews safe to fly.
To those at Kinloss, I'm proud of you xx
One thing which I failed to see on here is the idea that while the fleet has continued to fly a massive amount of checks have been performed on the fleet since the accident and again since the inquest, also throughout the time between.
I'm sure, okay scratch that, I know, there are a lot of checks being made to attempt to identify possible faults and to remedy those faults. That while it may be perceived as a risk to continue to fly, the attitude at ISK is anything but irresponsible to the crews safety, a great deal of measures have been put in place.
Had it not been for the loss of 230, the majority of these potential flaws and even obvious design flaws, would not have come to light. The Nimrod is probably the safest now than it has ever been as it is constantly being checked and double checked.
As simple as this may sound the majority of documents which are quoted, past investigations which have taken place, majority of the techie nature means nothing to me compared to the fact that the fleet is being scrutinised and examined with the intention of keeping her crews safe to fly.
To those at Kinloss, I'm proud of you xx
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Lab Queen,
I pretty much tried to say the same thing re. all the checks and work being done just recently, but it seemed to fall on deaf ears.
I genuinely believe there are those on here (and I'm not trying to start a slagging match!) that just do not want to listen unless what is said suits their own personal beliefs and agendas, hence the conversation goes round in circles with counterpoints and arguments and gets nowhere
Look at the recent suspension of one of the forum users - now, I'm not saying that I agree with all of what was said but I certainly didn't think it was bad enough to warrant the action taken, just because it didn't "toe the party line". It inferred one persons beliefs and as such that person surely has the right to express themselves just as much as some others on this forum, whether others agree with what he/she says or not?
NO-ONE at ISK wants to see an aircraft take to the skies in anything less than a safe condition to do so, certainly from the groundcrew side. But then what do groundcrew know, they are mostly ignored and trodden on or totally disrespected by the majority of commissioned officers, those same officers who refuse to believe what they are told by experienced groundcrew (in many cases, in the mistaken belief that a university degree gives them superior knowledge to a highly experienced techie - with specialist qualifications - who has been doing the job for many years!), then they suddenly put up their umberella's when something goes wrong!
I pretty much tried to say the same thing re. all the checks and work being done just recently, but it seemed to fall on deaf ears.
I genuinely believe there are those on here (and I'm not trying to start a slagging match!) that just do not want to listen unless what is said suits their own personal beliefs and agendas, hence the conversation goes round in circles with counterpoints and arguments and gets nowhere
Look at the recent suspension of one of the forum users - now, I'm not saying that I agree with all of what was said but I certainly didn't think it was bad enough to warrant the action taken, just because it didn't "toe the party line". It inferred one persons beliefs and as such that person surely has the right to express themselves just as much as some others on this forum, whether others agree with what he/she says or not?
NO-ONE at ISK wants to see an aircraft take to the skies in anything less than a safe condition to do so, certainly from the groundcrew side. But then what do groundcrew know, they are mostly ignored and trodden on or totally disrespected by the majority of commissioned officers, those same officers who refuse to believe what they are told by experienced groundcrew (in many cases, in the mistaken belief that a university degree gives them superior knowledge to a highly experienced techie - with specialist qualifications - who has been doing the job for many years!), then they suddenly put up their umberella's when something goes wrong!
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SecretSooty
100 % spot on, The thing is, your last paragraph is one of the reasons why the "experienced Techies" are leaving. Alongside the backward rotating nights, evenings, dayshifts that leave everyone drained both physically and mentally. THREE shift handovers a day to just ensure we get LOSS of continuity on big rects tasks. Beggars belief but as you say, we are mostly IGNORED. "Experienced Techie" days to do, OUT..
DS
100 % spot on, The thing is, your last paragraph is one of the reasons why the "experienced Techies" are leaving. Alongside the backward rotating nights, evenings, dayshifts that leave everyone drained both physically and mentally. THREE shift handovers a day to just ensure we get LOSS of continuity on big rects tasks. Beggars belief but as you say, we are mostly IGNORED. "Experienced Techie" days to do, OUT..
DS
I asked you earlier DV - "Are you saying that electrical ignition risks are infact an issue here?". You replied: "Simple answer yes."
Where exactly are you getting or inferring this from - are you saying this is what the QinetiQ report you highlight above actually says? Are you sure about this? What exactly does it say - assuming its contents are repeatable here? I'm not convinced its as simple as you're implying but not having seen the report I've got an open mind on the subject.
Where exactly are you getting or inferring this from - are you saying this is what the QinetiQ report you highlight above actually says? Are you sure about this? What exactly does it say - assuming its contents are repeatable here? I'm not convinced its as simple as you're implying but not having seen the report I've got an open mind on the subject.
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The thing is, your last paragraph is one of the reasons why the "experienced Techies" are leaving. Alongside the backward rotating nights, evenings, dayshifts that leave everyone drained both physically and mentally. THREE shift handovers a day to just ensure we get LOSS of continuity on big rects tasks. Beggars belief but as you say, we are mostly IGNORED. "Experienced Techie" days to do, OUT..
DS
100% spot on DS nobody is listening to what groundies have to say , all this talk from the so called people who know Nimrod and yet all we say our bit but nobody here wants to listen to what groundcrew say. We know more on this subject than anyone can imagine yet nobody listens.
DS
100% spot on DS nobody is listening to what groundies have to say , all this talk from the so called people who know Nimrod and yet all we say our bit but nobody here wants to listen to what groundcrew say. We know more on this subject than anyone can imagine yet nobody listens.
Last edited by KeepItTidy; 8th Jun 2008 at 11:11.
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DS and KeepItTidy, that's the very reasons that I myself left!
I'd been in long enough to see the wheel re-invented so many times and guess what - yep, it only ever worked when it was circular in form! Lol. The really annoying thing was when you tried to politely explain why some "fresh-from-uni-spotty-faced-little-know-it-all's" latest "great idea" was never going to work and you were either ignored or asked to be quiet in the interests of protocols.
I loved working on the Nimrods, the best aircraft I've ever had the challenge of spannering on and I do still miss it. I miss the banter as well, but I just couldn't accept the changes being made all around me whirlwind style. 3 days, 3 nights, 6 off was hard work but it had the required continuity to get the job done, and when averaged out (for the benefit of those who said it was too much time off) you actually worked more hours than an 8 to 5 day worker!
Back on-topic slightly, we now have a situation where a lot of people who haven't ever used a spanner on the aircraft seem to think they know better than those who know the aircraft's systems (in some cases both airframe and propulsion) intimately.... I wonder how many are/were officers..... Please don't have a go at me for that gents, I'm having a laugh! I've learnt a lot from this thread re. the legislative side of airworthiness issues and I'm grateful to those who have taken the time to explain things in great detail, but guys, don't get so wrapped up that you can't "see the metal for the rivets", listen to the techies as well please.
Unfortunately DS, we no longer have the likes of Roddy to keep the "juniors" in their place, hahaha. Guessed who I am now?? lol.
I'd been in long enough to see the wheel re-invented so many times and guess what - yep, it only ever worked when it was circular in form! Lol. The really annoying thing was when you tried to politely explain why some "fresh-from-uni-spotty-faced-little-know-it-all's" latest "great idea" was never going to work and you were either ignored or asked to be quiet in the interests of protocols.
I loved working on the Nimrods, the best aircraft I've ever had the challenge of spannering on and I do still miss it. I miss the banter as well, but I just couldn't accept the changes being made all around me whirlwind style. 3 days, 3 nights, 6 off was hard work but it had the required continuity to get the job done, and when averaged out (for the benefit of those who said it was too much time off) you actually worked more hours than an 8 to 5 day worker!
Back on-topic slightly, we now have a situation where a lot of people who haven't ever used a spanner on the aircraft seem to think they know better than those who know the aircraft's systems (in some cases both airframe and propulsion) intimately.... I wonder how many are/were officers..... Please don't have a go at me for that gents, I'm having a laugh! I've learnt a lot from this thread re. the legislative side of airworthiness issues and I'm grateful to those who have taken the time to explain things in great detail, but guys, don't get so wrapped up that you can't "see the metal for the rivets", listen to the techies as well please.
Unfortunately DS, we no longer have the likes of Roddy to keep the "juniors" in their place, hahaha. Guessed who I am now?? lol.
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Buoy 15, your posts aren't ever exciting, just confrontational, appeasing to the RAF and earlier in this thread downright disgusting and disrespectful.
Undemocratic or not I wish you would just **** off!
Undemocratic or not I wish you would just **** off!
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Buoy15:
So let's get this straight. You think that family members of those who died on XV230 are only posting on the forum to generate compensation. But almost everyone else on the forum thinks that your comments were despicable and warranted a temporary ban.
You were banned and you are now saying that this is not democracy. Stupid as well as crass, eh?
Jayand
Yes, for some un-democratic reason, I was - but I've served my pennance and I'm delighted to be back, reading exciting posts from you
Yes, for some un-democratic reason, I was - but I've served my pennance and I'm delighted to be back, reading exciting posts from you
You were banned and you are now saying that this is not democracy. Stupid as well as crass, eh?
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JFZ90.
Ask yourself this question, "why has AAR not been resumed?".
On the question of what is in the QinetiQ report; a statement that the risk level for the fuel system is "remote", and there are 30 reasons why it is not ALARP. And once again, if a system is remote and not ALARP, it is not safe.
This being the case, under the Health and Safety Act, MoD (as an employer) is failing in its duty to its employees and the general public.
DV
"Are you saying that the electrical ingnition risks are in fact an issue here?"
On the question of what is in the QinetiQ report; a statement that the risk level for the fuel system is "remote", and there are 30 reasons why it is not ALARP. And once again, if a system is remote and not ALARP, it is not safe.
This being the case, under the Health and Safety Act, MoD (as an employer) is failing in its duty to its employees and the general public.
DV
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buoy 15
I am annoyed that you have been allowed back so soon (I would have banned you for life following your comments) - I expected more from Danny and the rest of the Pprune team frankly, but there you go.
I think BEagle summed it up perfectly, you are not wanted here. Please go away and pedal your sick thoughts elsewhere.
I am annoyed that you have been allowed back so soon (I would have banned you for life following your comments) - I expected more from Danny and the rest of the Pprune team frankly, but there you go.
I think BEagle summed it up perfectly, you are not wanted here. Please go away and pedal your sick thoughts elsewhere.
JFZ90.
Quote:
"Are you saying that the electrical ingnition risks are in fact an issue here?"
Ask yourself this question, "why has AAR not been resumed?".
On the question of what is in the QinetiQ report; a statement that the risk level for the fuel system is "remote", and there are 30 reasons why it is not ALARP. And once again, if a system is remote and not ALARP, it is not safe.
This being the case, under the Health and Safety Act, MoD (as an employer) is failing in its duty to its employees and the general public.
DV
Quote:
"Are you saying that the electrical ingnition risks are in fact an issue here?"
Ask yourself this question, "why has AAR not been resumed?".
On the question of what is in the QinetiQ report; a statement that the risk level for the fuel system is "remote", and there are 30 reasons why it is not ALARP. And once again, if a system is remote and not ALARP, it is not safe.
This being the case, under the Health and Safety Act, MoD (as an employer) is failing in its duty to its employees and the general public.
DV
I assumed the AAR limitation was related to some of the unknown system-system behaviour issues inflight & pressure spikes etc. - hence nothing to do with electrical ignition issues as you seem to imply above? Edsett - can you comment on this?