Nimrod Information

[AC Ovee]

Winco, your words:

I don't know whether XV230 had an 'acceptable' leak the day of that fateful flight, but I would assume it did.

also, your words:

I have never ever accused or even suggested that this accident was the result of neglegence by anyone, including groundcrew.

You clearly indicated in the first statement that you believe the groundcrew were signing off leaks as acceptable faults when, in your opinion, no leaks are acceptable. Therefore you are questioning the judgement of the front line groundcrew. Bad judgement and decisons by leaders and managers in any profession can be thought of as negligence. I chose my words carefully when I suggested that you are bordering on accusing them of negligence. However, I do accept, having read your latest message, that it was not your intent to do so.

Regarding the concept of fuel leaks, I don't know how modern aircraft store fuel in their wings (ie bag tanks or integral tanks with sealant), but the Nimrod uses integral tanks and sealant. It is a fact that fuel can get under the sealant at its edges by access hatches, baffles and components, etc, and seep along the metal under the sealant and appear as a weep at a nearby rivet. The rivet is not the cause; its simply the escape route, so attempting to stop the leak by dealing with the rivet (from the outside) will actually make the leak worse. The proper way of dealing with the leak is to open up the tank and replace the sealant in the area of the leaking rivet(s). However, the simple act of going into the tank will disturb the sealant elsewhere and encourage yet another leak. Years ago it was acceptable for a tradesman to enter the tank with minimal drying time, while the sealant was still damp. Nowadays, the tank has to dry to the point that it is difficult to smell the fuel. This prolonged drying time leads to the sealant drying and hardening and becoming vulnerable to damage. Therefore, the groundcrew do not enter tanks to repair small leaks. I guess the experience of integral tanks might have encouraged the aviation industry to improve the sealants or use bags in modern times.

So, yes, every Nimrod flying today has a number of small wing tank fuel leaks; none of which present a hazard to flight safety. They were there when you flew them and they are there now. Not the same leaks, obviously, just the same problem. As an air eng I have no qualms with this policy.

Finally, we do not, under any circumstance, accept a fuel leak from a pipe. Pipes are removed (with difficulty sometimes), checked, and replaced if necessary, using new rubber seals in all cases. The pipe couplings could be better designed, but they are not purely Nimrod couplings; they are industry standard.

[MightyHunter AGE]

Fuel Leaks

Right then, wrt fuel leaks, the only acceptable leaks as ES says are ones in the integral tanks.

Any other leaks are investigted and rectified full stop.
I or any other engineer will not send an aircraft into the blue yonder with fuel leaks and I personally resent the implications Winco has posted on here.

Integral tank leak rates, off the top of my head from the 2(R)1 are as follows

STAIN: Where fuel wets an area around the leak of an area less then 2" in 2 hours

SEEP: Wets an area of 6" in two hours

HEAVY SEEP: Wets and area of over 6" in two hours but does not drip or run

RUN: Where fuel runs or drips at a rate of less than 10 drips per minute

UNACCEPTABLE LEAK: Where the run or drip rate is more than 10 drips per minute - rectify or lim fuel tank.

These facts are in the 2(R)1 and are for EXTERAL leaks ONLY.

I am currently in the Gulf and am here with the guys that saw the jet off and I can catagorically say that they did NOT send that jet up with known fuel leaks.
Any implications otherwise by members of this forum are slander and I would warn you against posting any more such comments.

[Winco]

Gentlemen,

I think that at last you might have hit the nail on the head!
Yes, when I crewed-in, I very occasionally would find a fuel leak (unless the Eng found it first!) So, what did we do?
1. If it was a loose union, get the groundcrew to tighten it up if possible.
2. If that couldn't be done, and the task was important - frame swap.

The problem today is that you guys don't have the comfort of being able to swap frames. Why? Because basically you are underfunded.

Now I don't in any way blame you guys one jot. On the contrary, I am certain that you are as frustrated, if not more so, than the aircrew are about it. My point is that these new 'acceptable' defects have been imposed upon you by those from above. It was never such before, so why, with an even older aircraft, is it allowed now? I know times have changed, but does anyone at all on this forum know of any other aircraft or fleet that gives you a card outlining where fuel leaks are acceptable?

MightyHunter AGE. Please don't take offence at my comments. They are not directed at you or the rest of your groundcrew and are not meant to belittle the outstanding work you all do. They are meant to highlight the restrictions, limitations etc that are being forced upon you. I don't believe for one minute that you want to send an aircraft airborne with a known fuel leak, but it appears that you are being forced to. Is that correct or am I reading this wrong? Do you as a crew chief, to the best of your knowledge, send an aircraft flying with a known fuel leak of any kind?

I don't know, but AC Ovee says that all the aircraft leak, as does Camelspyyder, indeed some on here go even further and say that they leak like sieves! (tell me Camelspyyder, are these guys all 'anonymous old has-beens'?)

Please stop accusing us of having a go at you. We are not having a go at anyone, least of all the groundcrew. But we must all face the 'facts' as given to us on this forum by current Nimrod operators, which clearly would indicate that the Nimrod fleet has a serious fuel leak problem.

[MightyHunter AGE]

Winco said
Do you as a crew chief, to the best of your knowledge, send an aircraft flying with a known fuel leak of any kind?

Of course I send an aircraft up that has known fuel leaks, that is what the adf log is for. If a leak is documented and catogarised in the 704 then that is acceptable iaw the 2(R)1.

What I think you mean is do I send an aircraft up that has a leak other than those documented, the answer to that is no. I have grounded aircraft on several occasions that have had fuel leaks and the aircraft has not flown until the leak has been rectified, period.

Where you are getting the idea that anyone would send an aircraft up with a known fuel leak is beyond me.

[Cpt_Pugwash]

Nimrod IPT

T D,
There are two Nimrod IPTs, one for the MRA4, and probably the one for which you are seeking information, the smaller MR2 team. This open source link http://www.bajars.co.uk/dlo_article_aug2006.htm gives a contact number. Hope this helps.

PW

[nigegilb]

It is good to thrash out the different types of fuel leaks and make some headway in the confusing answers given to PQs. Accepting the idea that there is such a thing as a safe fuel leak, it would appear that serious fuel leaks have occurred with Nimrod during AAR, specifically involving the AAR pipework. Nimrod AGE/Was Nae Me make the point that it is not possible to recreate the pressures the ac experiences in flight when testing on the ground. This concern with AAR Ops is borne out by the changes in Nimrod AAR SOPs following the crash. I made the point earlier that this change in SOP was not able to prevent a huge inflight fuel migration a few months after the XV230 tragedy. It is important not to go down a blind alley with the external fuel leaks and keep in mind the single skin design of the AAR system, the lack of bomb bay fire protection and the lack of fuel tank protection.

Assuming that XV230 was not sent up with a dangerous fuel leak on that fateful day, what was in the acceptable deferred defects page? Has anything changed since the crash that is no longer an acceptable deferred defect? Has there been a realisation about something that what was assumed to be safe, but is no longer deemed so?

[Tappers Dad]

MightyHunter AGE

You said :

Of course I send an aircraft up that has known fuel leaks, that is what the adf log is for. If a leak is documented and categorized in the 704 then that is acceptable law the 2(R)1.

So let me get this right here. You are saying that aircraft can fly if the leak is categorized in the 704.
Am I reading that correctly ?

[BEagle]

Entirely normal.

On most large aircraft of that vintage, a 'fuel map' is included in the F700. There are allowable drip rates from the undersurface beneath the fuel tanks and the known location of any such acceptable leaks is indicated on the 'fuel map'.

Leaks from elsewhere (such as fuel gallery pipes) are NOT acceptable, however.

[Winco]

BEagle,
We are from the same vintage ourselves, but the point that is confusing me is 'all' of these fuel leaks, and the general opinion that appears to exist that as long as they are in the adf log, then they are OK and/or safe. Some of the stories of 'offload' and 'upload' figures are alarming arn't they? Even with a bit of 'massage', the figures about fuel loss make worrying reading, and I would hazzard a guess that, if the figures are correct, the loss has not occurred from a dripping tank.

If we have a fuel tank with a known 'acceptable' leak in it (albeit small), and we suddenly throw a few thousand pounds of fuel into it, at pressure under AAR contiditions, at height and in turbulance, do you not agree that there is a strong possibility that the small leak could develope into a somewhat larger one?

You and I are familiar with minor leaks, and the Crew chief makes the point that all aircraft leak, which I wouldn't entirely disagree with. But my concern is that given the fact that the fleet is old and well past its sell by date: given the fact that some aircraft are reported as leaking like sieves and given the fact that we have lost an aircraft and I understand come close to losing another, do you not feel that there may just be a link between the leaks and the loss of XV230?

Best Wishes
TW

[Tappers Dad]

Open Question

Is it possible for ground crew to say an a/c is operating with a known flaw/defect possibly to do with AAR and it shouldn't fly?

And if it is possible, then due to operational pressures can a decision be taken by Nimrod IPT (integrated project team) to over rule the ground crew and say it must continue to fly ?

Just a Yes or No please

[MOA]

IPTs

All Nimrods come under the Team Nimrod IPT following the birth of DE&S.

[TheSmiter]

Pugwash provides a link above.

Those of us in possession of the Aug 2006 edition of Preview, the in-house magazine of the DPA (as was), will notice that someone has used an airbrush to erase the a/c no. from the nose of the first MR2 to undergo Equalized Maintenance last July. It (EM).... delivers savings on labour and spares, improves aircraft availability and makes for a simpler and more efficient aircraft maintenance programme.

I think you can guess which airframe it is.

[tucumseh]

To quote from the above article;


"It was also contracted as an incentive scheme under which BAE Systems (the prime service contractor) has the potential to derive profit increases equal to that of the MOD savings".

Taken literally, that means the MoD didn't actually save anything (and therefore generate funding to spend on something else) but rather BAeS derived extra profit at the expense of Operational Capability.

Something not quite right there. On the other hand, is it not now MoD policy (see Defence Industrial Strategy and DSTL Technology Strategy) to hand contracts on a plate to BAeS, thus placing them on a level playing field with Thales and other protected species?

[BEagle]

On the ground, the weight of the aircraft is supported by the three points of the undercarriage.

In flight, the weight of the aircraft is opposed by lift.

It follows that the wing root bending moment on the ground will be unlikely to be the same as that in flight. So the leak rate on the ground may well not be the same in flight - particularly with high centreline weights. This may well be exacerbated by turbulence...

But who can say?

The only real solution is to take firm action to stop any fuel leaks - but that is probably unachievable.

I have recently been advising other nations' AAR forces about the crucial need to ensure that offload figures from the tanker are accurate; receivers must also allow for the burn rate in contact when they resolve their upload figures, of course.

I recall the story of a RN Buccaneer. Recently back from modification with an AAR probe - so the pilot decided to have a joust with a passing tanker. All went fine - except that when the green light was seen and the "fuel flows" call was made by the tanker, nothing was seen to be coming into the receiver. "BŁoody old Crab fools" muttered the matelot and buggered off back to the boat. When they unlocked the nose to put the jet on the deck lift, guess what poured out.....? It had been swilling around the Blue Parrot radar. The cause was obvious - one outfit had fitted the probe, but the other mod - to fit the associated pipework - had yet to be incorporated.....

However, the same effect would be noted with a serious internal fuel leak - if tanker offload > (receiver state at endAAR - receiver state at startAAR) + (receiver burn from startAAR to endAAR), then there is obviously something amiss. If you have accurate engine fuel flowmeters with resettable counters, it would be possible to measure the burn in contact - but don't forget to allow for different fuel densities and fuel temperatures between tanker and receiver if you measure fuel in terms of mass rather than volume!

[TheSmiter]

I recall the story of a RN Buccaneer. Recently back from modification with an AAR probe - so the pilot decided to have a joust with a passing tanker. All went fine - except that when the green light was seen and the "fuel flows" call was made by the tanker, nothing was seen to be coming into the receiver. "BŁoody old Crab fools" muttered the matelot and buggered off back to the boat. When they unlocked the nose to put the jet on the deck lift, guess what poured out.....? It had been swilling around the Blue Parrot radar. The cause was obvious - one outfit had fitted the probe, but the other mod - to fit the associated pipework - had yet to be incorporated.....

I take it was then an ex-Parrot Beags? Bananas, bananas.

Is it my imagination, but wasn't the Nimwacs designed to use fuel to cool the radar? Until someone wondered how it would conduct its primary mission on minimums?

[Pontius Navigator]

Originally Posted by Tappers Dad

Open Question

Is it possible for ground crew to say an a/c is operating with a known flaw/defect possibly to do with AAR and it shouldn't fly?

Yes

And if it is possible, then due to operational pressures can a decision be taken by Nimrod IPT (integrated project team) to over rule the ground crew and say it must continue to fly ?

No

The IPT has no impact on operational decisions. The ground crew may be over ridden by an Engineering Officer, and Engineering Officer may be overridden by OC Eng Wg, Forward or whoever. OC Eng may be overridden by the Station Commander who, in turn, may be overridden by the AOC and AOCinC.

Once safely safe in the mighty jet the Captain can override the lot.

It was explained very nicely by my boss many years ago. He said, as sqn cdr I can order Flt Lt R to fly. He will accept my order and we will all board the aircraft. He will refuse to fly and, as a crew member, I will get out with the rest of the crew. After due consideration I will order him to fly. etc etc.

On another occasion, on an exercise (Gp Capt promotion exam) a captain at a remote dispersal reported his aircraft was u/s and he would not scramble. The stn cdr ordered him to scramble as his aircraft was a war goer and he wanted the 100% success. The captain refused.

The bottom line is the Captain holds the ultimate responsibility for accepting or rejecting the aircraft, not the IPT or anyone else.

[nigegilb]

PN if the Captain believes it to be safe he will fly. I think that is the point TD is making. Acceptable defects are just that, believed to be acceptable at the time.

You don't need to look far. AOC 2Gp gave specific clearance for the Nimrod to fly AAR in the days after the crash. Exceptional circumstances. As someone has already commented, exceptional circumstances end up being the norm. Is a Captain going to turn round and refuse to fly?

[Pontius Navigator]

Originally Posted by nigegilb

Is a Captain going to turn round and refuse to fly?

In all probability he will fly. The context was I believe:

Is it possible for ground crew to say an a/c is operating with a known flaw/defect possibly to do with AAR and it shouldn't fly?

Do we have any evidence that the ground crew said it should not fly?

The context of my reply was intended to show that the IPT may be the design authority but that there are many hands on the paddle even on the station.

On the assumption that an aircraft was declared at above normal level of risk - the old QRA Mandatory Launch for instance - the decision would be made at a higher level.

On one occasion my captain declared that he would not comply with a mandatory launch order, in peacetime, from a 4*. The captain would factor in his own appreciation, operational imperative and superior orders. In the current scenario, and I do not know the mission or its criticality, the mission success might save lives on the ground and the captain would factor that in.

Out.

[SpannerSpinner]

"The context of my reply was intended to show that the IPT may be the design authority"

The IPT ARE NOT the Design Organisation and never will be. That would mean the IPT are judge and jury and rightly so- they are far from it.

In the case of the MR2 it's BAE systems who are the DO and completely independent of the IPT.

Guys I don't post very often but there are an incredible amount of people who are adding dross and innaccuracies to this thread. Granted this is a rumour thread etc etc yawn zzz zzzzzzz but come on! Have some thought for people like TD, who are on here to get the truth and some facts that might help his quest. So too the crews who currently have to fly the Mighty Hunter.

Given the subject and knowing exactly who may read this, I suggest you take a reality check and realistically quantify your credentials for comment. I mean do people seriously think that after 10, 20 years off the fleet that they are STILL upto speed on tactics/equipment/eng procedure and the like? Will those crusty armchair nimrod engineers/safey engineers please step down- you're stifling the truth!

[Tappers Dad]

SS
What is the truth then can they over rule the ground engineers given the senario?