Nimrod Information
TS, I too should like to commend tucumseh's post. May I suggest that those minded to go on posting contrary views as to the arrangement of various widgets and flanges in the MR2 read that post again, indeed reread tuc's previous posts on this thread. He deals with the MOD woods, rather than contentious RAF trees. It seems to me that is where the thread should be concentrating, especially given, as tuc reminds us, the CinC's comments on the BOI's findings.
As to the review, I would hope that the QC is minded to call for a full Public Inquiry, and thus break out of any constraints placed on him to contain collateral damage to the MOD.
As to the review, I would hope that the QC is minded to call for a full Public Inquiry, and thus break out of any constraints placed on him to contain collateral damage to the MOD.
Mr Smiter Sir, you say
Do you have any other details, such as who the QC is, where and how the inquiry will operate, who it will accept input from, etc?
airsound
I understand the QC has been given a very tight timeline (3 months) to report.
airsound
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airsound
ref yr last, regrettably no to all the above - although I agree that would be very useful info to have. I was hoping someone on here could let us all know - TD or nigegilb perhaps?
All I know is that his remit is wide ranging and he will be kicking down doors - I look forward to the final report, whether thru this QC or via a full Public Inquiry. Either way, 'the noise', as Gordy puts it, is not going to die down.
Do you have any other details, such as who the QC is, where and how the inquiry will operate, who it will accept input from, etc?
All I know is that his remit is wide ranging and he will be kicking down doors - I look forward to the final report, whether thru this QC or via a full Public Inquiry. Either way, 'the noise', as Gordy puts it, is not going to die down.
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I would agree with the above. Remaining tight tipped for the minute, but genuinely know nothing about QC. 3 months is a good thing in my opinion. Also coincides with the start of the Herc Inquest. The noise is only gonna get louder folks.
Smiter & Chug
Thank you. However, I do not regard myself as a “whistleblower”. Every single fact I mention here is available, or can be gleaned from, open source material or papers obtained under the Freedom of Information and Data Protection Acts. I’ve often wondered why on earth they release such damning evidence. Is it arrogance or ignorance? The QQ report is a typical example. It is a catalogue of breaches of the regulations. Admittedly, often you have to dig deep, collate, understand linkages and apply decades of training, but it’s all there.
This is the tragedy here. Sir Clive’s assertion that airworthiness regulations have not been implemented properly is NOT A REVELATION. I look forward to the QC asking why the likes of CDP and various Mins(AF) have steadfastly supported those who regard it as optional, while ruling against those who stand firm and seek to implement. In fact, galaxies of “Stars” know about this and have turned a blind eye. In a way, I admire their consistency over many years, through many reorganisations and changes in postholders, but they’ve backed the wrong horse and it’s time to rescind these rulings and rigorously enforce the regulations. And I hope they don’t take the easy option and pick on someone in the Nimrod IPT. This has been going on so long, it is systemic and people are no longer required to have the basic core competencies needed to manage attaining, or maintaining, airworthiness. Quite literally, they make it up as they go along.
Thank you. However, I do not regard myself as a “whistleblower”. Every single fact I mention here is available, or can be gleaned from, open source material or papers obtained under the Freedom of Information and Data Protection Acts. I’ve often wondered why on earth they release such damning evidence. Is it arrogance or ignorance? The QQ report is a typical example. It is a catalogue of breaches of the regulations. Admittedly, often you have to dig deep, collate, understand linkages and apply decades of training, but it’s all there.
This is the tragedy here. Sir Clive’s assertion that airworthiness regulations have not been implemented properly is NOT A REVELATION. I look forward to the QC asking why the likes of CDP and various Mins(AF) have steadfastly supported those who regard it as optional, while ruling against those who stand firm and seek to implement. In fact, galaxies of “Stars” know about this and have turned a blind eye. In a way, I admire their consistency over many years, through many reorganisations and changes in postholders, but they’ve backed the wrong horse and it’s time to rescind these rulings and rigorously enforce the regulations. And I hope they don’t take the easy option and pick on someone in the Nimrod IPT. This has been going on so long, it is systemic and people are no longer required to have the basic core competencies needed to manage attaining, or maintaining, airworthiness. Quite literally, they make it up as they go along.
And I hope they don’t take the easy option and pick on someone in the Nimrod IPT.
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Duct Replacement
Following the incident with XV227 the damaged duct section was replaced on all Nimrods. I understand that this took almost a year to complete because ducts had to be manufactured for each aircraft. Can anyone tell me if the replacement was "like for like", or was the new duct different in design? I ask the question because photographs show the damage duct as being covered with mental braiding whilst the replacement appears to be covered in fabric.
DV
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Mr Point,
Any maintenance policy for the SCP and other similar ducts would have concentrated on mitigation against duct failure due to internal corrosion, because that was what caused that incident. No policy would have been implemented to specifically reduce the temperature of the air inside or outside the duct, because the air temperature at that location is what it is, due to operation of the system. Anyway, lets say that they had, co-incidentally, decided to fit new and better insulation around the duct. It still would not have stopped the leaking fuel (from wherever it came) from coming into contact with the either the hot pipe directly or the insulation. Here is something that you probably don't know (its not in the BOI report): The source of the hot air in the SCP duct is the exit of the HP compressor, known as P3/T3. At sea level, at 100% power, T3 on an engine test bed has been recorded at 500 degrees. The BOI conducted ground tests on installed engines (as per the report) to establish the likely temperature of the SCP duct during the AAR sequence on 230. Due to a lack of ram air on the ground, the SCP pre-cooler overheated with only 90% power and the duct temp at the SCP elbow was recorded at 400 degrees at that time. At 90% power, the engine is just coming into its designed power range, so Ts and Ps, although very high, are far from maximum. This concurs with the previously mentioned test bed figures. At 20,000 ft, (OAT -25 ish) during the AAR sequence, the record shows that the engines were almost at max power, so T3 would have been much closer to 500 degrees, with a reduction factor to account for the lower OAT. Then we can reduce the temperature on the outside of the brand new insulation and assume no gaps in it due to a clever way of having static insulation on a fixed pipe with a seemless connection to insulation on a bellows pipe. The existing insulation has been recorded to drop the temperature by 16 degrees, so we'll work on more than that, say 30 degrees. The bottom line is that the outside of any new insulation, with the engines close to max power, is still going to exceed 400 degrees, IMHO.
So, it would be incorrect to say that any new maintenance policy implemented as a result of 227's incident would have prevented the fire. I would agree that it might have done so, but that is not what you said at the outset. There were definitely failures in other areas of maintenance policy and, if you want to bang a drum, have a look at the BOI's comments about the NSC and fuel coupling failure trend analysis. These 2 failures are at the heart of the matter.
Regards
Ed Sett
Any maintenance policy for the SCP and other similar ducts would have concentrated on mitigation against duct failure due to internal corrosion, because that was what caused that incident. No policy would have been implemented to specifically reduce the temperature of the air inside or outside the duct, because the air temperature at that location is what it is, due to operation of the system. Anyway, lets say that they had, co-incidentally, decided to fit new and better insulation around the duct. It still would not have stopped the leaking fuel (from wherever it came) from coming into contact with the either the hot pipe directly or the insulation. Here is something that you probably don't know (its not in the BOI report): The source of the hot air in the SCP duct is the exit of the HP compressor, known as P3/T3. At sea level, at 100% power, T3 on an engine test bed has been recorded at 500 degrees. The BOI conducted ground tests on installed engines (as per the report) to establish the likely temperature of the SCP duct during the AAR sequence on 230. Due to a lack of ram air on the ground, the SCP pre-cooler overheated with only 90% power and the duct temp at the SCP elbow was recorded at 400 degrees at that time. At 90% power, the engine is just coming into its designed power range, so Ts and Ps, although very high, are far from maximum. This concurs with the previously mentioned test bed figures. At 20,000 ft, (OAT -25 ish) during the AAR sequence, the record shows that the engines were almost at max power, so T3 would have been much closer to 500 degrees, with a reduction factor to account for the lower OAT. Then we can reduce the temperature on the outside of the brand new insulation and assume no gaps in it due to a clever way of having static insulation on a fixed pipe with a seemless connection to insulation on a bellows pipe. The existing insulation has been recorded to drop the temperature by 16 degrees, so we'll work on more than that, say 30 degrees. The bottom line is that the outside of any new insulation, with the engines close to max power, is still going to exceed 400 degrees, IMHO.
So, it would be incorrect to say that any new maintenance policy implemented as a result of 227's incident would have prevented the fire. I would agree that it might have done so, but that is not what you said at the outset. There were definitely failures in other areas of maintenance policy and, if you want to bang a drum, have a look at the BOI's comments about the NSC and fuel coupling failure trend analysis. These 2 failures are at the heart of the matter.
Regards
Ed Sett
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DV, my understanding, looking at the existing ducts and photos is that it was a like for like replacement of insulation. Most likely it was the same insulation that went back on, provided it wasn't obviously damaged. After all, there was no new maintenance policy to do anything other than replace the duct and the joint seals.
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EdSet100; You could be right. It is just that photographs that I have of XV227, immediately after the incident, do not show any material "cladding" around the pipe.
Also, with reference to Mr Points comments, the XV227 recommendations ask for a maintenance and lifing policy for the damaged and similar ducts. Whilst we can all agree that it is most unlikely that the damaged duct will fail again during the life of the Nimrod, we should be concerned about the others. Lets face it, if a section of your car exhaust fails due to aging, then there it a good chance that other sections are in a similar condition. That is why BAE were asked to carry out a survey back in 2005, which is still outstanding.
DV
Also, with reference to Mr Points comments, the XV227 recommendations ask for a maintenance and lifing policy for the damaged and similar ducts. Whilst we can all agree that it is most unlikely that the damaged duct will fail again during the life of the Nimrod, we should be concerned about the others. Lets face it, if a section of your car exhaust fails due to aging, then there it a good chance that other sections are in a similar condition. That is why BAE were asked to carry out a survey back in 2005, which is still outstanding.
DV
DV
According to the MoD briefing, the vent from the No 1 tank blow-off is on the side of the fuselage in a direct line (of airflow) forward of the 7 tank dry bay.
airsound
According to the MoD briefing, the vent from the No 1 tank blow-off is on the side of the fuselage in a direct line (of airflow) forward of the 7 tank dry bay.
airsound
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airsound; Yes I have read that, and I have seen photos of the blow off in relation to the SCP external ducting (the likely source of ignition), but how does the fuel get up, in a sufficient quantity, to the dry bay?
It is not the dry bay that is in the direct air flow, it is the SCP external ducting
DV
It is not the dry bay that is in the direct air flow, it is the SCP external ducting
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Fuel Paths
DV,
Not a Nimrod specialist, but if I understood the Press Briefing correctly the fuel can track back down the fuselage from the No 1 tank blow-off valve when it operates, and enter the gaps in the fairings and panels by the 7 tank dry bay and alongside the main hot air pipe to the SCP. Given this the fuel can then come into contact with the gap between the two types of insulation, which the BOI found on most aircraft, where the hot air pipe is not protected and hence fuel touching bare metal at approximately 400 degrees C can catch fire. The insulating material would hold the fuel in once it reached there. I think most people were convinced this was the source of ignition, but even the BOI recognised that the fuel could also have come from elsewhere eg a fuel pipe coupling. If it was the no 1 tank blow off valve it is surprising to me that it has not happened before in 20+ years of AAR, however, I am sure a Nimrod expert will correct any mis-conceptions I may have or any mis-use of terminology!
JB
Not a Nimrod specialist, but if I understood the Press Briefing correctly the fuel can track back down the fuselage from the No 1 tank blow-off valve when it operates, and enter the gaps in the fairings and panels by the 7 tank dry bay and alongside the main hot air pipe to the SCP. Given this the fuel can then come into contact with the gap between the two types of insulation, which the BOI found on most aircraft, where the hot air pipe is not protected and hence fuel touching bare metal at approximately 400 degrees C can catch fire. The insulating material would hold the fuel in once it reached there. I think most people were convinced this was the source of ignition, but even the BOI recognised that the fuel could also have come from elsewhere eg a fuel pipe coupling. If it was the no 1 tank blow off valve it is surprising to me that it has not happened before in 20+ years of AAR, however, I am sure a Nimrod expert will correct any mis-conceptions I may have or any mis-use of terminology!
JB
Last edited by John Blakeley; 11th Dec 2007 at 15:08. Reason: Sp
DV & JB
Perhaps I should have prefaced my remarks by saying that I am in no way a Nimrod expert.
However, what I gathered at the briefing accords with what JB says - and of course you're right DV, the dry bay is not itself protruding into the air flow in the way that the SCP external ducting is.
What did strike me as a bit odd is the supposition that any blow-off from the No 1 tank should last for long enough and contain sufficient fuel to maintain a fire of such proportions. Any thoughts?
airsound
Perhaps I should have prefaced my remarks by saying that I am in no way a Nimrod expert.
However, what I gathered at the briefing accords with what JB says - and of course you're right DV, the dry bay is not itself protruding into the air flow in the way that the SCP external ducting is.
What did strike me as a bit odd is the supposition that any blow-off from the No 1 tank should last for long enough and contain sufficient fuel to maintain a fire of such proportions. Any thoughts?
airsound
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Thanks John, I have read all that. If you look at Diagram 14, which is a photograph of No1 tank blow off valve, you can only see the SCP (external) ducting in the direct air flow. What vent, scoop or joint encourages the fuel to go up in to No.7 tank dry bay?
DV
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EdSet,
I agree that there is no certainty that a comprehensive maintenance review following the XV227 incident would have prevented the fire on XV230. In my early post I did not say that this would be the case, although I concede that I believed it was likely.
I would be very interest to find out how often, both prior to and following September 2006, there has been fuel or traces of fuel found in the No 7 tank dry bay. I find it hard to believe, as John Blakeley has stated, that this is the first time that fuel has entered this bay, or another bay that is close to a hot air pipe on the aircraft. As you know, even before 2003, AAR had been conducted on an occasional basis in a fairly wide range of temperatures.
I agree that there is no certainty that a comprehensive maintenance review following the XV227 incident would have prevented the fire on XV230. In my early post I did not say that this would be the case, although I concede that I believed it was likely.
I would be very interest to find out how often, both prior to and following September 2006, there has been fuel or traces of fuel found in the No 7 tank dry bay. I find it hard to believe, as John Blakeley has stated, that this is the first time that fuel has entered this bay, or another bay that is close to a hot air pipe on the aircraft. As you know, even before 2003, AAR had been conducted on an occasional basis in a fairly wide range of temperatures.
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BOI 2-31
An average of 9 AAR sorties for the fleet between 1993-2005.Then in 2006 18 AAR sorties, 9 of which XV2230 did, 7 of which were in Aug 2006 why XV230 and not any of the other ac in theatre ????
An average of 9 AAR sorties for the fleet between 1993-2005.Then in 2006 18 AAR sorties, 9 of which XV2230 did, 7 of which were in Aug 2006 why XV230 and not any of the other ac in theatre ????
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Fuel Source
I am sure the events of 5th November (XV235) must have tilted the scales towards a leaking coupling. It must also cast doubt on QinetiQ, who according to Des Browne, the CAS and the Stn Cmdr, "has conducted an independent investigation into the fuel system and confirm that, in the light of the measures taken since the crash, the fuel system is safe to operate"
DV
DV
Last edited by Distant Voice; 12th Dec 2007 at 09:16.