Nitrogen in Fuel Tanks

[One Outsider]

Basic aerodynamics states that in order for an a/c to climb, lift must be more than weight/gravity and thrust must be more than drag.

Well Leewan, I suppose then that it should be easy for you to provide evidence for that claim.

Simple vectors and such, should suffice.

[SNS3Guppy]

All engineers now require fuel tank safety training level 2 for aircraft with a pay load above 7500lb or 30 passengers or more.

In the UK, you mean?

That wouldn't be 'all' engineers. Just some.

And yes, TWA 800 was shot down.

[hawker man]

Not just the Uk this is a EASA requirement but only for the Engineers who certify on the Aircraft that meet the 7500 pound or 30 passengers or more.

[violator]

Guppy

There are so many technical mistakes in your posts that is discredits you. In fact it's a poignant example of someone with a little bit of knowledge applying it too freely: making wild statements with clear factual errors.

"Air conditioning plants" don't cook up the fuel tank, or fuel for that matter.

The packs are a heat source near the centre fuel tank. Hence they patently do heat up the fuel.

Further, the fuel gauges in the 747 CWT and wings are capacitance gauges, passive

Capacitance probes, whether AC or DC, are not passive. They are active, energized with a hi-z current.

Even then, whereas the heat source for the target was the packs, which are located beneath the center wing tank, filling the tank with nitrogen wouldn't have helped them.

Ignoring your contradiction, of course inerting the ullage would have helped. Liquid aviation fuel doesn't burn, its vapour does. Hot fuel and an inert ullage is not flammable. Filling the tanks with nitrogen would have prevented the explosion.

In most flight operations, the CWT seldom gets used

Empty tanks are the worst case - the entire tank is vapour.

Despite this, the "fix" has been to have a minimum of 17,000 gallons of fuel in the CWT if the fuel pumps are to be used. That's it. The big threat, and the fix is business is usual, with a little bit of fuel.

To prevent dry-running. You don't seem to realise it's fuel vapour which ignites, not liquid fuel. No oxygen, no fire.

[SNS3Guppy]

The packs are a heat source near the centre fuel tank. Hence they patently do heat up the fuel.

Packs cause heat, and were most likely the heat source for the missile. Packs do not "cook up" the fuel, nor do the packs use up the fuel, nor has heating of center wing tank fuel by proximity of the packs been responsible for a CWT exploding. Accordingly, my statement was correct.

Capacitance probes, whether AC or DC, are not passive. They are active, energized with a hi-z current.

The capacitance probes did not, do not, and have not represented an ignition source, and are a passive source of fuel sampling (as opposed to float gauges or another electromechanical source). Accordingly, my statement was correct.

Ignoring your contradiction, of course inerting the ullage would have helped. Liquid aviation fuel doesn't burn, its vapour does. Hot fuel and an inert ullage is not flammable. Filling the tanks with nitrogen would have prevented the explosion.

No, in fact; it wouldn't. A missile strike in proximity to the fuel tanks would have caused plastic deformation of the fuel cell (which it did), and most likely expansive deformation of the wing tanks as well (which it did). Aside from the plastic deformation, rupture of the tank occurred, meaning that as fuel exits the cell, and vapor, the presence of nitrogen in the cell is irrelevant; it's going to burn and explode anyway. Accordingly, my statement was correct.

Everything burns, and everything vaporizes before it burns as part of the chemical process of pyrolysis. This is a given. With rupture of a fuel cell, however, nitrogen in the tank does noting to prevent a subsequent explosion. Nitrogen in the tank will suppress arcing from a contained ignition source, but this wasn't the case.

Empty tanks are the worst case - the entire tank is vapour.

Quite correct. However, you're responding to a statement that the CWT wasn't used, and not being used, the alleged ignition source, the fuel transfer pump, was deactivated and also not in use...meaning the source claimed to have triggered the explosion wasn't active or energized.

A tank which is vapor doesn't necessarily burn or explode until a combustible mixture is reached, and thus the notion that simply because the tank does not contain fuel makes it likely to explode is in error. Moreover, currently the 747 continues to fly with empty center wing tanks, and the only requirement to address this matter is that if any fuel is to be used from the tank, it have 17,000 lbs to start (a small amount of the total capacity of the CWT). Even with the "fix" of having 17,000 lbs of fuel in the CWT, there's a LOT of vapor still remaining. Doesn't seem anything at all has been fixed, does it? This is because there was never a need for a fix. The aircraft was hit with a missile.

To prevent dry-running.

No, this is not at all the case. In fact, the provision to stop using fuel via the primary jettison/override pumps when the fuel quantity reaches 3,000 lbs. belies your point. One simply stops transferring at 3,000 lbs using the jettison/override pumps,and finishes the last 3,000 lbs using the scavenge pumps (or one stops using the jettison/override pumps in the CWT when either pump low pressure light illuminates). It's important to understand that the CWT primary fuel pumps, the jettison/override pumps, don't empty the tank anyway...depending on the airplane, they'll drain it down to 2,600 to 4,000 lbs, and that's it. After that, the remaining must always be removed with the scavenge pump.

When 17,000 lbs of fuel are in the CWT, there's still plenty of vapor, to go around. My statement was correct.

Now...if there is really an explosion hazard in the CWT...isn't it remarkable that TWA 800 is the only one to have exploded out of hundreds of thousands of operating hours, and isn't it remarkable that it occurred in an aircraft not using CWT fuel, in which the ignition source wasn't energized, and isn't it particularly remarkable that if indeed this explosion hazard does exist, nothing has been done to fix it save for carrying a little fuel when the pumps are to be turned on? Not much of a fix for such a deadly threat.

The problem is, the problem didn't exist; TWA 800 didn't simply explode, pack heating not withstanding. it was shot down.

You don't seem to realise it's fuel vapour which ignites, not liquid fuel. No oxygen, no fire.

You don't seem to realize that although I fly professionally and have spent many years as a professional "engineer" (mechanic), I've spent a number of years as a professional firefighter...and yes, I really do understand that vapor ignites. You may not understand that fuel vaporizes rapidly, and with a breach of a tank and the admission of oxygen, there is indeed a fire. TWA 800 was shot down.

[TURIN]

You don't seem to realize that although I fly professionally and have spent many years as a professional "engineer" (mechanic), I've spent a number of years as a professional firefighter..

How many years have you spent checking your 'facts'?


At least two 737s have exploded on the ramp when cwt fuel vapour has exploded after prolonged and intense use of air con packs on the ground.

[hawker man]

http://www.caasd.org/atsrac/FAA_PI-E...quirements.pdf

SNS3GUPPY

Have a look at the link above i think you will find a few Aircraft have had fuel tank explosions either on the ground or in the air. Also look at all the trouble EASA have gone to just to reduce the risk.
http://www.easa.eu.int/ws_prod/g/doc...20Part-145.pdf

You will also find that every maintenance manual for Aircraft that fall into the catergory of this requirement has a warning on every maintenance task that it is considered CDCCL (critical design configeration control limitations) so a lot time and money has been spent on this and you say the problem does not exist. If you have access to a maintenance manual of a Boeing or Airbus take a look and you will see what I mean.

[violator]

Guppy,

Packs cause heat, and were most likely the heat source for the missile. Packs do not "cook up" the fuel, nor do the packs use up the fuel, nor has heating of center wing tank fuel by proximity of the packs been responsible for a CWT exploding. Accordingly, my statement was correct.

No one said that the packs use fuel or a designed to heat the tank, nevertheless they clearly do heat the tank and the fuel. Heat from the packs can quite easily raise the temperature of the centre tank above the LFL.

The capacitance probes did not, do not, and have not represented an ignition source, and are a passive source of fuel sampling (as opposed to float gauges or another electromechanical source). Accordingly, my statement was correct.

To the first point, cap probs can be ignition sources in two ways. Firstly, if they are poorly bonded a lightning strike can cause arcing. Secondly, they provide (through their harnesses) a route for high energy to enter the tanks.

They are clearly active! A potential difference is applied to them, a current flows. Simply because other in-tank components may work differently doesn't make them any less active.

A missile strike in proximity to the fuel tanks would have caused plastic deformation of the fuel cell (which it did), and most likely expansive deformation of the wing tanks as well (which it did). Aside from the plastic deformation, rupture of the tank occurred, meaning that as fuel exits the cell, and vapor, the presence of nitrogen in the cell is irrelevant; it's going to burn and explode anyway

But your original comment suggested that an inert ullage wouldn't have helped TWA800 had there been an ignition source in fuel because you implied that inert ullage wouldn't have prevented the liquid fuel from exploding. You used your point to try and show how fuel tank inerting systems are useless.

Nitrogen in the tank will suppress arcing from a contained ignition source, but this wasn't the case.

You're in no position to state what the case was or wasn't.

However, you're responding to a statement that the CWT wasn't used, and not being used, the alleged ignition source, the fuel transfer pump, was deactivated and also not in use...meaning the source claimed to have triggered the explosion wasn't active or energized.

Firstly, there is nothing preventing dry-running of 747-100 fuel pumps. Secondly, the FQIS was implicated, which (as we've established) is an energy source, is active and has no intrinsic safety barrier.

A tank which is vapor doesn't necessarily burn or explode until a combustible mixture is reached, and thus the notion that simply because the tank does not contain fuel makes it likely to explode is in error

No one said that. At the same temperature an empty tank full of vapour is a worse than a non-empty tank with the same vapour.

oreover, currently the 747 continues to fly with empty center wing tanks, and the only requirement to address this matter is that if any fuel is to be used from the tank, it have 17,000 lbs to start (a small amount of the total capacity of the CWT). Even with the "fix" of having 17,000 lbs of fuel in the CWT, there's a LOT of vapor still remaining. Doesn't seem anything at all has been fixed, does it?

This is due to two things. Firstly, SFAR88 should have eliminated any energy sources (such as short-circuiting in FQIS wire bundles). Secondly, the fuel level is to prevent pump dry-running, which is another potential energy source.

However, ignoring your attempt to make this point support your idea that TWA800 was shot down, it is relatively valid. 747 Classics don't have intrisically safe fuel systems and the 747 Classic FQIS still has 1e-6 pfh chance of introducing a high energy source (resulting in a catastrophic case). It wouldn't be certified today.

The aircraft was hit with a missile.

You've said nothing to support that theory. It's OK having an outlandish theory, but you have to provide some evidence. You haven't done that yet.

No, this is not at all the case. In fact, the provision to stop using fuel via the primary jettison/override pumps when the fuel quantity reaches 3,000 lbs. belies your point. One simply stops transferring at 3,000 lbs using the jettison/override pumps,and finishes the last 3,000 lbs using the scavenge pumps (or one stops using the jettison/override pumps in the CWT when either pump low pressure light illuminates). It's important to understand that the CWT primary fuel pumps, the jettison/override pumps, don't empty the tank anyway...depending on the airplane, they'll drain it down to 2,600 to 4,000 lbs, and that's it. After that, the remaining must always be removed with the scavenge pump.

When 17,000 lbs of fuel are in the CWT, there's still plenty of vapor, to go around.

I don't understand your points: 17 klbs of fuel in the CWT ensures that all pumps are covered and ensures that no dry-running can occur. It's not designed to reduce the amount of vapour in the tank, it's designed to mitigate ignition risks (dry-running fuel pumps).

[quote]Now...if there is really an explosion hazard in the CWT...isn't it remarkable that TWA 800 is the only one to have exploded out of hundreds of thousands of operating hours, and isn't it remarkable that it occurred in an aircraft not using CWT fuel, in which the ignition source wasn't energized, and isn't it particularly remarkable that if indeed this explosion hazard does exist, nothing has been done to fix it save for carrying a little fuel when the pumps are to be turned on?[/quote[

That low frequency of 747 fuel tank explosions isn't surprising, it's to be expected. Boeing calculated it to be a 1e06 pfh event, they have occured at about that rate.

'Not using CWT fuel' implies large ullage, which as we've discussed is the worst case.

The FQIS were indeed energised, they are active components. There is no intrinsic safety on FQIS harnesses. There is nothing to automatically prevent pumps dry-running - there are obvious ignition sources.

Ensuring there is 17 klbs of fuel in the CWT prevents the pumps dry-running, SFAR88 ensures the FQIS doesn't introduce ignition sources. 747 Classics are dinosaurs with few flying, as usual cost overrides safety, which is why few (if any) will be fitted with a fuel tank inerting system. 787 and A350 will have full fuel tank inerting systems.

You don't seem to realize that although I fly professionally and have spent many years as a professional "engineer" (mechanic

That seems to be the problem, you're a pilot not an engineer. Your entire theory is bad science. You use a little knowledge to try and cement a poorly-thought through theory that cannot be tested. You erroneously use vague examples to support your ideas. You ignore evidence that doesn't support your ideas.

[cessnapuppy]

and so say all of us.

this is taking on the characteristics not of a reasoned debate but of religious proselytizing. There will be no 'convincing' done here as the facts are convincing in and of themselves. All not convinced wont ever be.

[TURIN]

Good though, innit?

[Peter Fanelli]

TWA 800 was not shot down by a missile, it was brought down by a meteorite.
Picture such an object entering the earth atmosphere just over the horizon from the perspective of someone on the beach of Long Island and there you have your flaming object apparently rising from the surface and striking the aircraft. By the time it got to the aircraft it may have been quite small but still hot enough to have provided an ignition source and now it's just laying on the ocean floor looking a lot like any other rock.

That's my belief anyway, ever since I had a close encounter with a meteorite myself while flying early one morning in Australia. And I don't mind telling you it scared the crap out of me at first.

Flame away.

[SNS3Guppy]

That seems to be the problem, you're a pilot not an engineer.

Come again? I am an engineer. I believe I made that clear.

I am also a pilot.

I also happen to have had a number of years professional experience as a firefighter, as previously mentioned.

MITRE CAASD || File not found

This report addresses 17 cases of fuel tank explosions, 3 of which are of unknown origin. Four were from wing fires, of which TWA 800 is not implicated. Four were electrostatics, also not relevant according to the official report which blames wiring, or the official fix, which blames the pump. 2 were lightening strikes, which was not the case for TWA 800, and are irrelevant. 2 claim pumps or wiring related to the cause...that's two out of seventeen. One was a small bomb...if we're to believe that it was wiring or a pump, we can discount the bomb incident. 1 was maintenance action. What this leaves of the 17 cited fuel tank explosions is only two that are relevant, and three unknowns. So much for the 17.

HOWEVER...12 hull losses are cited for military aircraft, consisting of B52 and B707 airframes...and every single one occurred with cut fuels, specifically JP4. No cases of explosions using only jet fuel...all had gasoline in the mix.

On the civil side is a B707 in Maryland, fueld with JP4. A DC8 in Toronto, using JP4. The Iranian 747 previously identified, and using, of course, JP4. A b727 is cited as having exploded while using Jet A, but of course it was destroyed by a bomb.

A 737 in Manilla is cited for unknown causes, and was using Jet A. TWA 800 is cited...but involves conjecture as to the ignition source. A B737 in Bangkok exploded, this time with Jet A1, but no known ignition source.

Nearly every case of an explosion involved Gasoline cut fuels (as has been the case with every recorded in-flight explosion following a lightening strike...go figure), and the few that didn't were either a bomb, or can't be identified.

What this really means is there's no evidence of any significance in that report of aircraft with Jet A in the tank exploding due to a CWT heated by packs, with faulty wiring. In fact, there's no evidence. Baseless conjecture, at best.

What's the common thread among nearly all the mishaps given? JP4. The remainder involve unidentified ignition sources and one identified bomb.

TWA 800 wasn't using JP4.

You're in no position to state what the case was or wasn't.

Nobody is. However, it's irrelevant, as TWA 800 was shot down.

At the same temperature an empty tank full of vapour is a worse than a non-empty tank with the same vapour.

Actually that's not true, particularly if there's an explosion and the tank is breached. The additional volume of the empty tank occupied by the small extra amount of vapor mixture won't contribute nearly as significantly to the explosion and conflagration as a partially full tank will after rupture; the partial fuel load then vaporizes and adds immensely to the energy of the explosion and the ensuing fire.

However, unless either situation reaches a combustible mixture, the quantity of fuel in the tank is irrelevant with respect to an explosion.

Firstly, there is nothing preventing dry-running of 747-100 fuel pumps. Secondly, the FQIS was implicated, which (as we've established) is an energy source, is active and has no intrinsic safety barrier.

Well yes, actually, there is...firstly a flight engineer who turns off the CWT pumps and sees a bright amber low pressure light telling him to do so, and secondly...while the FQIS was "implicated," this has occurred with little more than ancillary "evidence."

You've said nothing to support that theory.

Well, of course, there are witness reports. A few documented here, among the hundreds of reports which saw the missile leave the surface, streak upward, and the saw the explosion...

TWA Flight 800: EYEWITNESS STATEMENTS TO POLICE
TWA Flight 800: STATEMENTS BY EYEWITNESSES
The Flight 800 Investigation
TWA Flight 800 Eyewitness Quotes
Witness sketches get no sunlight at 'Sunshine Hearing'
Review of the Official TWA Flight 800Witness Reports
TWA Flight 800 Eyewitness Evidence
Sketch located by independent researcher
The Flight 800 Investigation
http://twa800.com/witnesscd/Witness649.pdf

Relevant data from the Eyewitness Group Factual Report:

* Based on the data, 183 witnesses said they saw a streak of light, 201 said they saw one or more explosions, 100 said they heard one or more explosions, and 339 said they saw a fireball.
* Of the 183 who observed a streak of light, 102 gave information about the origin of the streak. Six said the streak originated from the air, and 96 said that it originated from the surface. Of the 96 who said it originated from the surface, 40 said it originated from the sea and 10 said it originated from land.
*One hundred and twenty-eight witnesses reported an immediate end to the streak, 85 described it ending in an explosion, 32 said it ended in a fireball, and 11 said it ended in a flash.

Several reports, very rapidly suppressed, identified traces of explosive residue among the wreckage, as well as input on trajectories and potentials. For example:
Flight 800 Petition: Section 3
Flight 800 Petition: Section 2
Flight 800 Petition: Section 1
The Flight 800 Investigation

There's that pesky nagging fact that it's never happened before, and it couldn't be duplicated, even by the investigators...

As late as March 15, 1997 NTSB was having difficulty proving the theory they had settled on months earlier. From a Newsday article: TWA Tests Inconclusive Attempt to ignite fuel fails. From the article:

" FEDERAL AIR-CRASH investigators, testing theories about mechanical failures that could have ignited the center fuel tank of TWA Flight 800, have managed to produce a buildup of static electricity on two parts from a similar 747's tank by spraying them with jet fuel. But so far the voltage has been insufficient to ignite fuel vapors, sources in the investigation said, making the tests inconclusive. The tests, conducted at Wright Patterson Air Force Base in Ohio, are part of the National Transportation Safety Board's increasingly complex effort to explore possible mechanical causes for the Flight 800 disaster.

Investigators have produced low levels of voltage through the experiments, but not enough to create a spark, a safety-board source said. The tests are being conducted under various conditions of temperature and humidity.

One aerospace engineer expressed doubt [that] a static discharge could have created a spark powerful enough to ignite vapors in the center fuel tank, particularly in the thinner air at 13,700 feet.

``The question is, how could a little spark make this thing go bang,'' said Paul Czysz, a St. Louis University aerospace engineering professor. ``Even if it discharged, is there enough energy in that discharge to cause the fuel air mixture to burn? And if it does burn, is there enough concentration of the burning to heat the air temperature high enough that you get a detonation wave?''

Now, of course, to explain themselves, the NTSB did in fact show a video of a CWT exploding (Explosion Dynamics Laboratory), implying that they were able to create a similiar situation. It was a 1/4 scale model, and they didn't simply use kerosine, but pumped hydrogen into their model, and propane, before setting it off...and they weren't able to achieve ignition through any combination of jet fuel and FQIS or pump useage. They used a dedicated ignition device, because it was the only way they could get the explosion to put on film. Still, the visual of a *simulated* CWT exploding is very emotionally moving...just a lie. What it really amounted to was little more than a "mythbusters" exercise, and was far from scientific.

Let's ignore the fact that the NTSB was never able to establish, let alone prove that an explosive fuel mixture existed in the CWT, and take it on faith that there was such a mixture present. Set aside that a competent FE missed two pumps on, and ignored the amber low fuel (indicating low fuel pressure from those pumps) lights. Ignore the lack of evidence of any ignition source. Let's ignore the hundreds of witnesses who saw a streak of light originate at the surface, and proceed to the aircraft where they saw an explosion. Let's ignore the fact that even the military ballistics report claims being inconclusive and not having adequte information, or that it was part of the government documentation (much of which changed from the early statements and reports, to it's final itineration). Let's ignore that such an event has never occurred before, or that the substantiation from reports such as the previously cited SFAR88 document can only cite irrelevant events using different fuel and circumstances, and that the report lumps in bombs, lightening strikes, and unknown causes in an attempt to link them to the TWA800 event. Let's ignore the witness drawings, the witnesses not allowed to testify, the evidence which was *misplaced,* and the recanted testimonies from some notable and authoritative sources (including weapons experts at China Lake). What we're really left with is a coverup of a shootdown of TWA 800.

[leewan]

TWA 800 was not shot down by a missile, it was brought down by a meteorite.

For a moment, I thought that was a sarcastic comment. ( Is it ?)
It must be very, very unlucky to be hit by one as the statistics would be exponentially great.

[TURIN]

Based on the data, 183 witnesses said they saw a streak of light, 201 said they saw one or more explosions, 100 said they heard one or more explosions, and 339 said they saw a fireball.
* Of the 183 who observed a streak of light, 102 gave information about the origin of the streak. Six said the streak originated from the air, and 96 said that it originated from the surface. Of the 96 who said it originated from the surface, 40 said it originated from the sea and 10 said it originated from land.
*One hundred and twenty-eight witnesses reported an immediate end to the streak, 85 described it ending in an explosion, 32 said it ended in a fireball, and 11 said it ended in a flash.

So, out of 183 "witnesses", and of the 102 who gave info, less that half say the missile came from the sea and less than 10 % say it came from land.

Where did the others think it came from? Little green men?

Eye witness reports are notoriously bad.

I "witnessed" a mid air collision between a hang-glider and paraglider many years ago and I could have sworn blind that I heard a shotgun go off. "They were being shot at" the conspiracy theorists would say.
What I heard was the hang-gliders leading edge tube (main spar) snap in half at the time of impact.

Eye witnesses prove very little but often add to confusion and stoke up improbable theories for those with an axe to grind.

I will not accept half baked beliefs against hard evidence. The aviation industry has spent millions introducing inerting systems and altered maintenance practices, not to mention redesigning fuel systems to comply with more recent regulation.

You (and others) say all this has been done to cover up a crime?

Nope.

[Cusco]

Well, guys: I'm beginning to regret having started this thread.

However thanks to all of your helpful links I now understand the principle and practice of 'inerting' fuel tanks on passenger jets and for that I'm very grateful.

I don't frequent PPRuNe very often and the main reason is the kind of stuff which has littered the rest of this thread culminating in the inevitable PPRuNe style name calling and sh*t throwing.

I have read the conspiracy theories with some interest and will leave you all to argue the toss.

Usually, when views are so entrenched in different sides of an argument no resolution or agreement ever ensues: It looks as if that's the way this thread is going.

Cheers

Cusco

[Peter Fanelli]

For a moment, I thought that was a sarcastic comment. ( Is it ?)
It must be very, very unlucky to be hit by one as the statistics would be exponentially great.

Nope, no sarcasm at all.
It never occurred to me that it could have been a meteorite until two things happened to me. The first was as I stated in my post my own close encounter with a meteorite while in flight at night.
The second was a few years ago I was driving to work at BWI and the traffic report was on and suddenly the reporter went crazy about what he was seeing in the sky. It was later revealed that a satellite had fallen out of orbit and re-entered the atmosphere that morning. The surprise for me was when I turned into the airport and could see the smoke trail for myself I was surprised that it was not close to vertical from sky to ground but almost horizontal and in fact from my point of view appeared to gain altitude as it burned up.
Thinking about the experience that day I came to the conclusion that maybe the "missile" that was reported striking TWA800 was in fact a meteorite.

If I'm wrong I'm wrong, but in the absence of any other firm evidence I'm prepared to believe it.

It must be very, very unlucky to be hit by one as the statistics would be exponentially great.

Would you like to hear about the time I ran into a screw in flight?

[subsonic69]

screw in flight

pls elaborate... im interested ( not being sarcastic in anyway )...

[cessnapuppy]

pls elaborate... im interested ( not being sarcastic in anyway )...

Me neither - this guy is a **** magnet...stay away!! LOL*

If I'm wrong I'm wrong, but in the absence of any other firm evidence I'm prepared to believe it.

That 'firm evidence' wouldnt include Viagra by any chance, would it??? ROFL








*A loose screw in the sky finds its way to you: not impossible, airlines dont just 'fly about in the sky' but travel on well defined 'air highways' so while that does narrow the available area for **** to be in, I dont get why this screw will hang around till you got there.

Did you keep the screw? Maybe connect it to any other flights in your area during that time frame?

[violator]

Come again? I am an engineer. I believe I made that clear.

I am also a pilot

You said:

I fly professionally and have spent many years as a professional "engineer" (mechanic)

So are you a mechanic, an "engineer" or an engineer? A mechanic is not an engineer.

Quote:
You're in no position to state what the case was or wasn't.

Nobody is

I think the NTSB are in a better position than any of us. But regardless of that, I'm glad you've accepted that you cannot rationally say that a missile hit TWA800.

Well yes, actually, there is...firstly a flight engineer who turns off the CWT pumps and sees a bright amber low pressure light telling him to do so, and secondly

A flight crew member acting correctly is maybe a 1e-6 pfh function, which is approx 1e-5 over a flight. A light bulb is about a 1e-5 pfh function. <1e-5 pfh doesn't support any case worse than a major safety case - dry-running of pumps in tanks is now a catastrophic safety case. This is the reason why older types have had automatic centre tank pump shut off retrofitted (737NG) and why centre tank minimum fuel procedures have been adopted.

secondly...while the FQIS was "implicated," this has occurred with little more than ancillary "evidence."

I'm glad you've accepted that FQIS was implicated. And as we've discussed on the 747-100 there is no intrinsic safety barrier preventing high energy from entering the tank through the FQIS harnessses.

Actually that's not true, particularly if there's an explosion and the tank is breached.

I didn't talk about a tank rupture, I talked about the explosion risk. A tank full of vapour and empty of fuel is a worse case than a tank not empty of fuel. More component failures may result an explosion, potential across more structure has the capability to arc.

The additional volume of the empty tank occupied by the small extra amount of vapor mixture won't contribute nearly as significantly to the explosion and conflagration as a partially full tank will after rupture; the partial fuel load then vaporizes and adds immensely to the energy of the explosion and the ensuing fire.

I really don't understand this point, you haven't shown that a missile hit TWA800 and there's no evidence that the tank was ruptured from the outside. The contribution of a full or not-full tank to a missile explosion is irrelevent until you've established there was a missile.

Let's ignore the fact that the NTSB was never able to establish, let alone prove that an explosive fuel mixture existed in the CWT, and take it on faith that there was such a mixture present. Set aside that a competent FE missed two pumps on, and ignored the amber low fuel (indicating low fuel pressure from those pumps) lights. Ignore the lack of evidence of any ignition source. Let's ignore the hundreds of witnesses who saw a streak of light originate at the surface, and proceed to the aircraft where they saw an explosion. Let's ignore the fact that even the military ballistics report claims being inconclusive and not having adequte information, or that it was part of the government documentation (much of which changed from the early statements and reports, to it's final itineration). Let's ignore that such an event has never occurred before, or that the substantiation from reports such as the previously cited SFAR88 document can only cite irrelevant events using different fuel and circumstances, and that the report lumps in bombs, lightening strikes, and unknown causes in an attempt to link them to the TWA800 event. Let's ignore the witness drawings, the witnesses not allowed to testify, the evidence which was *misplaced,* and the recanted testimonies from some notable and authoritative sources (including weapons experts at China Lake). What we're really left with is a coverup of a shootdown of TWA 800.

Neither the NTSB nor anyone can prove a theory. Vapour in the tanks was clearly above the lower flammability limit, it had the capability to support combustion. The temperature in the tank was 38-52 deg C. The lower flammability limit of Jet A was 35.8 deg C.

Dry-running fuel pumps was not necessarily the source of ignition, but the pumps rely on pressure switches, harnesses, light bulbs and a fallible human to shut them off. As Boeing themselves have documented, it's well above 1e-9 per flight hour.

FQIS is a potential ignition source.

TURIN has helpfully discussed the witnesses.

Now let's consider the facts: Boeing themselves have submitted systems fault tree analysis that shows that the probability of 747-100 FQIS introducing high energy into the tank is 1e-6 pfh. It needs to be 1e-9 fh. This alone is compelling evidence that the 747-100 was an unsafe, flawed design and that it was only a matter of time before a centre fuel tank explosion occured.

Idon't frequent PPRuNe very often and the main reason is the kind of stuff which has littered the rest of this thread culminating in the inevitable PPRuNe style name calling and sh*t throwing.

What name-calling? This is a technical debate, what's wrong with it?

[SNS3Guppy]

So are you a mechanic, an "engineer" or an engineer? A mechanic is not an engineer.

You may be getting wrapped around the axle with UK terminology and use of the term "engineer" and "mechanic."

But regardless of that, I'm glad you've accepted that you cannot rationally say that a missile hit TWA800.

I said no such thing. There is no question that TWA 800 was shot down and the matter covered up. There is great ambiguity in the NTSB report and the information contained therein, as well as other agency input, the exclusion of significant amounts of testimony, the recanting of testimony, public exclusion, and many other details surrounding the case which are far from typical of an NTSB investigation. I can rationally say that TWA 800 was shot down and the matter covered up. The NTSB cannot rationally say that the CWT exploded from the FQIS or a fuel pump or caused the mishap.

I'm glad you've accepted that FQIS was implicated. And as we've discussed on the 747-100 there is no intrinsic safety barrier preventing high energy from entering the tank through the FQIS harnessses.

You misunderstood.

The FQIS was "implicated" in that it was alleged to have been a source of ignition, with no proof whatsoever beyond an allegation. Moreover, the NTSB and contracted specialist parties were 100% unable to duplicate a scenario in which this could possibly have happened. It's never happened before, there's no proof that it's happened before, and when they put on their little demonstration for the cameras, the simulation in a specially built tank with a specially built ignition source (not found in the aircraft) failed 100%...until they filled the tank with hydrogen and propane...also not found in the tank. In other words...their efforts to duplicate the explosion in any way, shape, or form...failed.

I didn't talk about a tank rupture, I talked about the explosion risk.

Which is entirely dependent upon a combustible mixture being present in the tank. The presence of vapor doesn't guarantee an explosive mixture. The tank was ruptured, however, and caused deformation of the adjacent inboard wing tanks, as well.

The contribution of a full or not-full tank to a missile explosion is irrelevent until you've established there was a missile.

As it is until one has established the contribution of an ignition source...which hasn't happened, either. There have been 26 shootdowns of commercial aircraft with surface to air man portable missiles...but no fuel tank explosions using Jet A which can be pointed directly to either the fuel pump or the FQIS...and there's nothing available to which the NTSB or any other party can point, that shows the FQIS or pump(s) or associated wiring as implicit in the event, save for allegations without foundation or evidence.

On the other hand, although stripped from the reports and excluded from the opportunity to testify, hundreds of witnesses saw a missile leave the surface arc upward, and strike the aircraft, followed by an explosion. Nobody saw any arcing in the fuel tank.

FQIS is a potential ignition source.

As is a missile.

Me neither - this guy is a **** magnet...stay away!! LOL*

That 'firm evidence' wouldnt include Viagra by any chance, would it??? ROFL

Well...we've certainly attracted a professional to the discussion. Thanks for the contribution. One can only wonder what nuggets of brilliance might emerge if the poster were older than say, 14 years of age.

So, out of 183 "witnesses", and of the 102 who gave info, less that half say the missile came from the sea and less than 10 % say it came from land.

Where did the others think it came from? Little green men?

Eye witness reports are notoriously bad.

Eye witness reports notoriously conflict, they are not necessarily "bad." The conflict is critical to understanding perspective, and the reasons they conflict often give valuable insight into what has taken place. What's different is just as important as what is the same.

There weren't simply 180 witneses...there were hundreds, on the order of nearly 800, who saw the event. These witnesses were not in the same location, and did not see it from the same vantage point, or necessarily see it at the same beginning moment or ending moment. One may fully expect that what they saw will be relayed in differing terms. What is interesting about many of the witness statements, however, is that their comments, and in fact their drawings illustrating what they saw, portray the first sighting of the event as originating at the surface...not in flight. Moreover, the witnesses included pilots (commercial and military), professionals, and others with a unique perspective on the matter.

Witness reports were quickly dismissed by investigators as these were very damaging to the case being built. The government worked very hard to cover up what had happened and to build an alternate theory...any alternate theory, while grasping at straws. Even the CIA video produced kept flashing on the screen "Not a Missile" to reinforce the concept that it wasn't a missile. Anything but a missile...and the FQIS and fuel pump wiring would have to do..even in the absence of any proof. Or ancillary evidence. Or evidence of any kind.

You (and others) say all this has been done to cover up a crime?

You (and others) would be best to put words in your own mouth, and not mine. I didn't say that.

Cover up yes. Cover up a crime? That would depend on perspective. Is it a crime that so many people died? Yes. Is it a crime that the truth was withheld? yes. At a time when the US government did not want the US to be seen as vulnerable to a terrorist act, it was very much in their interest to paint the event as anything but. However, this was a precursor which lead to the attacks on 09/11...terrorists who found that even a major public event such as the shootdown of TWA 800 could be covered up knew that they needed to do something so grandiose and so public that there was no way it could be hidden...which occurred with the events of 09/11.

No such thing as inerting systems, tosh.

No one, other than you, has suggested any such thing.

Not just the Uk this is a EASA requirement but only for the Engineers who certify on the Aircraft that meet the 7500 pound or 30 passengers or more.

Whether it be the UK, CAA, or EASA at large, this is still not "all." Just EASA.