Nimrod Information
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Ed Set, thanks for the comprehensive reply. I am trying to get my head round the BoI conclusions. AAR pressure was thought to be insignificant below 120psi, but no studies had been carried out on the cause of surges or the cumulative effect of surges. Ground testing equipment only tests up to 50 psi and the BoI have ordered that a 50psi limit be reintroduced.
This aircraft has been plagued by pressure surges and fuel leaks in recent times, many of them impossible to re-create on the ground. I just found it hard to understand why the 50psi limit was removed in the first place, when these conditions were not able to be re-created in controlled tests.
This aircraft has been plagued by pressure surges and fuel leaks in recent times, many of them impossible to re-create on the ground. I just found it hard to understand why the 50psi limit was removed in the first place, when these conditions were not able to be re-created in controlled tests.
You received your personal briefing by the BoI team on the 5th at ISK as a direct result of Graham Knight's personal intervention. Do you think CAS wanted to go up there and face the music?
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Gents, I hesitate to mention this in case it detracts from the real issues here, but do you think the practice of remaining 'in contact' after fuel transfer is complete might have an impact on the seals in the AAR system? I understand that AAR enroute to the Falklands was generally 'offload complete, disconnect', but more recently receivers, in general (as I do not have knowledge of specific procedures/techniques of relevance), tend to stay in contact after fuel transfer, thereby burning the tanker's fuel, sort of, until some relevant point in time or space. Just a thought.
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Just going off topic for a second , recent comments about the Nimrod not designed to fly in the hotter areas of operation it was never built for it . Surely when manufacturers design aircraft they have a broad range of high temps to low temps into consideration. If this is the case can we say the same about the Hercules,VC10 Tristar ? Are they operating in areas out of there temprature range .?
Ive lately had the chance to do some low level maratine flying and bloody hell it gets thrown about like nothing ive seen before and the aircraft is rugged to handle this kind of flying , yet as we know in the sandy regions there is no requirement to throw it about the sky so less stresses on things. Just something that I been thinking about
Ive lately had the chance to do some low level maratine flying and bloody hell it gets thrown about like nothing ive seen before and the aircraft is rugged to handle this kind of flying , yet as we know in the sandy regions there is no requirement to throw it about the sky so less stresses on things. Just something that I been thinking about
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Magners,
The manufacturers do have limits that the aircraft is tested to, but the summer temperatures in theatre often exceed these limits.
However, as you quite correctly say, other aircraft in theatre are subject to the same temperatures. Ironically, due to the current tasking, the Nimrod is having significantly less G-stress placed it than twenty years ago.
The manufacturers do have limits that the aircraft is tested to, but the summer temperatures in theatre often exceed these limits.
However, as you quite correctly say, other aircraft in theatre are subject to the same temperatures. Ironically, due to the current tasking, the Nimrod is having significantly less G-stress placed it than twenty years ago.
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Mr Point wrote
Which even more ironically you can't say about the crews at the moment...
CS
Ironically, due to the current tasking, the Nimrod is having significantly less stress placed on it than twenty years ago.
CS
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Gents, I hesitate to mention this in case it detracts from the real issues here, but do you think the practice of remaining 'in contact' after fuel transfer is complete might have an impact on the seals in the AAR system? I understand that AAR enroute to the Falklands was generally 'offload complete, disconnect', but more recently receivers, in general (as I do not have knowledge of specific procedures/techniques of relevance), tend to stay in contact after fuel transfer, thereby burning the tanker's fuel, sort of, until some relevant point in time or space. Just a thought.
A perfectly accepted 'safe' procedure at the time - but who'd volunteerto do it now!!!??
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Burning the tanker's fuel is/was done on the tanker's booster pumps only. Consequently, the pressure surges, although frequent, were always well below 50 psi. I recall pressure fluctuations (which is a more accurate description) ranging between 15 and 25 psi as we flew along together. It wasn't done for fun. Range and/or endurance was enhanced significantly. The Herc guys did the same on the S Atlantic airbridge until the tanker had to head north.
And I would add that, provided the current proceures are adhered to, the Nimrod will not now vent while remaining in contact and "burning the tanker's fuel". After all, we would be burning our own fuel from a much lower level in the tanks and replacing that fuel to that same low level (which is well below the vent pipes and blow-off valves).
Regards
Ed Set
And I would add that, provided the current proceures are adhered to, the Nimrod will not now vent while remaining in contact and "burning the tanker's fuel". After all, we would be burning our own fuel from a much lower level in the tanks and replacing that fuel to that same low level (which is well below the vent pipes and blow-off valves).
Regards
Ed Set
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I stated earlier that the MoD has been briefing that dual wall pipes are difficult to maintain (seals) and are more difficult to detect fuel leaks than single skin systems. I assume the last bit was said without a trace of irony. Well this is the reply I received from an experienced engineer
"No problems at all really. The maintenance would require 2 couplings, (one for the inner pipe, one for the outer) whereas on a single wall pipe you would have one. The outer pipe then has "overboard" drain points so that should the main pipe seep / weep / fail, the secondary gland drains the fuel overboard. These drains are engineered in such a way that if one is dripping then you know to within a small area where the problem lies."
I note the MoD briefing did not mention cost.
"No problems at all really. The maintenance would require 2 couplings, (one for the inner pipe, one for the outer) whereas on a single wall pipe you would have one. The outer pipe then has "overboard" drain points so that should the main pipe seep / weep / fail, the secondary gland drains the fuel overboard. These drains are engineered in such a way that if one is dripping then you know to within a small area where the problem lies."
I note the MoD briefing did not mention cost.
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Nigegilb,
The Nimrod has a similar leak detection system in the area of the double skinned pipework in the crew cabin. Any leakage into the interspace will drip/run into a bottle below the lowest part of the pipework and operate a floatswitch with a light on the eng's panel. Immediate Actions: stop AAR. If the bottle overflows, the surplus fuel is then directed into the interspace in the fuselage tanks and is then vented overboard at the back of the fuselage. Neat system.
You probably know more than me on this subject, so I'll ask you this: is double-skinned fuel pipework mandatory only when the pipes are inside the pressure shell, i.e where the crew and pax/cargo share the same air?
If so, this will explain why MOD 715 on the Nimrod didn't double-skin throughout the bomb bay, which is outside the pressure hull.
Regards
Ed Set
The Nimrod has a similar leak detection system in the area of the double skinned pipework in the crew cabin. Any leakage into the interspace will drip/run into a bottle below the lowest part of the pipework and operate a floatswitch with a light on the eng's panel. Immediate Actions: stop AAR. If the bottle overflows, the surplus fuel is then directed into the interspace in the fuselage tanks and is then vented overboard at the back of the fuselage. Neat system.
You probably know more than me on this subject, so I'll ask you this: is double-skinned fuel pipework mandatory only when the pipes are inside the pressure shell, i.e where the crew and pax/cargo share the same air?
If so, this will explain why MOD 715 on the Nimrod didn't double-skin throughout the bomb bay, which is outside the pressure hull.
Regards
Ed Set
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Ed, with reference to CAA Regs double skinned pipework is focussed where there is a higher risk of fuel tank explosion. All the mods are contained in SFAR 88, Airworthiness Notice 55 issued by the CAA and EASA. In the case of the BBJ it concerns double skin pipes feeding the aux fuel tank. Things like proximity to conditioning packs would raise the probability of fuel fire/explosion. Operators failing to comply, (in the case of a 4 year old BBJ, kit cost $180,000 similar fitting costs), will have the aux tanks made inoperable.
Given that the Nimrod shares the same skies as all civil airliners then it would be interesting if a route could be engineered for the CAA to inspect a Nimrod on line?
Given that the Nimrod shares the same skies as all civil airliners then it would be interesting if a route could be engineered for the CAA to inspect a Nimrod on line?
Last edited by nigegilb; 6th Dec 2007 at 21:13.
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Winco 'Nor too has the fact that the bomb bay has no fire suppression fitted.'
Been on the MR2 for longer than my first marriage and I reckon I know a thing or 2 about it but there are somethings about bomb bay fire suppression that I can't get my head around.
How exactly do you fill a VENTILATED bomb bay with fire suppressant and, more importantly, keep it there?
What sort of fire suppressant could endure in a ventilated bomb bay?
How much (of a suitable fire) suppressant would be required to fill an empty MR2 bomb bay (the largest continuous bomb bay, excluding the B52, in NATO)?
Where the f
k would you put all the containers for the fire suppressant?
Perhaps a few armchair MR2 experts can shed some light on that one. Maybe Jimmy Jones could explain it to me when I meet him in a dark alley.
One further question. Can anyone tell me which prominant Nimrod 'expert' was involved in approving the Nimrod fuel system including the AAR system? You might find the answer interesting.
FG
(sorry I'm cross. It isn't endearing.)
How exactly do you fill a VENTILATED bomb bay with fire suppressant and, more importantly, keep it there?
What sort of fire suppressant could endure in a ventilated bomb bay?
How much (of a suitable fire) suppressant would be required to fill an empty MR2 bomb bay (the largest continuous bomb bay, excluding the B52, in NATO)?
Where the f
k would you put all the containers for the fire suppressant?Perhaps a few armchair MR2 experts can shed some light on that one. Maybe Jimmy Jones could explain it to me when I meet him in a dark alley.
One further question. Can anyone tell me which prominant Nimrod 'expert' was involved in approving the Nimrod fuel system including the AAR system? You might find the answer interesting.
FG
(sorry I'm cross. It isn't endearing.)
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FG,
You are the first person I think to ask this question.
I've been pondering this since it was first brought up on this thread as I don't know how all those screaming for it propose to do it.
To give you an idea of civvy regs a cargo compartment fire extinguishing system must fill 5% by volume of the compartment with extinguisher. A suppression system must the maintain 3% by volume of extinguisher. This will typically mean a high rate fire bottle followed by a low rate bottle in a sealed compartment. Those compartments certified for carriage of live animals will have a ventilation system that will shut off and isolate the compartment in case of fire. The detectors are smoke detectors not heat detectors. I know a bit about the Nimrod and don't know how you could achieve a credible bomb bay fire extinguishing system.
You are the first person I think to ask this question.
I've been pondering this since it was first brought up on this thread as I don't know how all those screaming for it propose to do it.
To give you an idea of civvy regs a cargo compartment fire extinguishing system must fill 5% by volume of the compartment with extinguisher. A suppression system must the maintain 3% by volume of extinguisher. This will typically mean a high rate fire bottle followed by a low rate bottle in a sealed compartment. Those compartments certified for carriage of live animals will have a ventilation system that will shut off and isolate the compartment in case of fire. The detectors are smoke detectors not heat detectors. I know a bit about the Nimrod and don't know how you could achieve a credible bomb bay fire extinguishing system.
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Originally Posted by
One further question. Can anyone tell me which prominant Nimrod 'expert' was involved in approving the Nimrod fuel system including the AAR system? You might find the answer interesting.
Give him a break - he's just trying to make up for his previous incompetance!
Regards - keep safe in the Sandpit
PS. tell Mrs Fatter Mk2 that dinner was tops!
Vage!
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Vage Rot and FATTER GATOR
This is taking on the rather depressing aspects of a smear campaign but when is this approval supposed to have taken place?
Quote:
Originally Posted by
One further question. Can anyone tell me which prominant Nimrod 'expert' was involved in approving the Nimrod fuel system including the AAR system? You might find the answer interesting.
Fatter me old mate!! That would be Jimmy Jones then!!
Originally Posted by
One further question. Can anyone tell me which prominant Nimrod 'expert' was involved in approving the Nimrod fuel system including the AAR system? You might find the answer interesting.
Fatter me old mate!! That would be Jimmy Jones then!!
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Mick Smith
Ah yes another talented MR2 comentator and 'campaigner'. Welcome to the fray.
2 contributors to the thread commenting on Jimmy Jones hardly consists of a smear campaign, unless you are a sensationalist journalist.
2 contributors to the thread commenting on Jimmy Jones hardly consists of a smear campaign, unless you are a sensationalist journalist.
SVS
Best make that 3. Given the slagging the MR2 force has had to put up with over the last year or so, any 'expert' who has blamed current ops for the loss of XV230 when what actually brought the jet down was a design fault which was present when (if I recall his media assertions correctly) that 'expert' was one of those responsible, then he should expect a good shoe-ing in return. Not that it'll bring any of those good 14 men back.
I accept that the airworthiness system has fallen down in not recognising the magnitude of the risk, but we didn't put it there!
CLA
Best make that 3. Given the slagging the MR2 force has had to put up with over the last year or so, any 'expert' who has blamed current ops for the loss of XV230 when what actually brought the jet down was a design fault which was present when (if I recall his media assertions correctly) that 'expert' was one of those responsible, then he should expect a good shoe-ing in return. Not that it'll bring any of those good 14 men back.
I accept that the airworthiness system has fallen down in not recognising the magnitude of the risk, but we didn't put it there!
CLA
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That really isnt an answer is it. The suggestion seems to be that Jimmy Jones was responsible for the problems with AAR experienced by the Nimrods flying over Afghanistan, even a cursory reading of the BOI - which blames a succession of changes to the system - indicates that couldnt be the case. If this palpably false claim doesnt constitute a smear, I dont know what does.