Aviation - fuel tank explosions, TWA Flight 800, Concorde, etc.

Originally posted by elpasys
"Filtering or rapidly pumping a liquid that is a relatively poor electrical conductor, like jet fuel, can result in a static charge being created much faster than it dissipates." [i.e. entropy growth]
"When the accumulated charge exceeds the ionization potential" [i.e. maximum entropy state]
"of the air above the liquid, it can discharge from the liquid surface as a spark. The energy of the spark can initiate an explosion if the liquid is flammable and the composition."

More:
Chevron
Aviation fuels
2. Aviation Turbine Fuel Performance

Thats the best one I've heard in years mate!!

So your telling me, that a fuel (in contact with steel/aluminium all the time) builds up a charge, and then sparks to the same steel/aluminium?

To stop the aircraft as a whole building up a static charge, they earth it during refuelling.

Washington D.C., June 6, 1989, Beechjet 400.

"At approximately 4:00 p.m. CST the airplane departed from Jackson enroute to National Airport in Washington, DC. Line service then began refuelling operations. Operations manager advised that the fuel truck was grounded to the airplane and also to the fuel ramp grounding point. Line personnel then began to service the aft tanks. Prior to service, there was approximately 200 pounds of fuel remaining in the tanks. After pumping five gallons into the aft tank through the aft filler port, line personnel reported hearing a hissing noise followed by a bang. Fuel surged out of the filler opening and covered the line service personnel. At this point, refuelling was terminated and the pilots were contacted. After the cabin interior seats were removed to gain access to the aft fuel tank, it was found to be torn loose from all 14 fuselage attach points. The tank had expanded significantly from internal pressure. The forward access panels on the tank were removed for internal viewing. The inside of the tank exhibited very heavy carbon deposits throughout the tank and especially on the upper surface of the horizontal support frames within the tank. These deposits indicate some type of fire or detonation occurred inside the tank."

More:
Service History/Fuel Tank Safety Level Assessment

Originally posted by elpasys

"Filtering or rapidly pumping a liquid that is a relatively poor electrical conductor, like jet fuel, can result in a static charge being created much faster than it dissipates." [i.e. entropy growth]
"When the accumulated charge exceeds the ionization potential" [i.e. maximum entropy state]
"of the air above the liquid, it can discharge from the liquid surface as a spark. The energy of the spark can initiate an explosion if the liquid is flammable and the composition."

More:
Chevron
Aviation fuels
2. Aviation Turbine Fuel Performance

You missed this bit from your same link

To prevent explosions triggered by a static discharge, well designed fuel handling systems use bonding and grounding (or earthing), pumping rate limits, and time for charge dissipation (relaxation time), before the fuel is exposed to air.6 Military jet fuels and international Jet A-1 require the use of an additive to increase the electrical conductivity of the fuel. Conductivity improving additives are also called anti-static additives or static dissipator additives. Use of the additive reduces the hazard of charge accumulation for handling situations that are less than optimum. The additive does not prevent charge generation, rather it increases the rate of charge dissipation by increasing fuel conductivity.

And yes you have to ground an aircraft while you fuel it, to dissipate all static build up. Though honestly chances of static from pumping are just about zero (maybe its higher in dry climates), they control the speed that you pump at and the pressure, it’s all governed by the hydrant truck. Jet-A is really not that different then diesel fuel used in trucks, and we used to fuel our diesel ground service equipment and run it off of Jet-A


Its funny I was an aviation fueler here in Florida and I have never heard of Entropy, Delays for Fuel stabilization (plenty of fuel delays though, LOL. Means that there are too many planes and not enough fuelers), or fuel weathering (unless you mean the density change associated with temperature meaning that the fueler was unable to deliver the poundage of fuel requested). Now it could be that these factors are a bigger concern in area’s where it’s drier and more prone to static discharge, but you think that I would have at least come across these terms before.

Then there are the wing vents that open to the outside atmosphere, and there are only two, not one per tank. To my knowledge they cannot be closed, and if the center is overfilled it spills over to the wings, and if the wings are overfilled the fuel spills out onto the ramp out these vents. I have even seen aircraft go out that are so full that the fuel is splashing out of the wing as the wings bounce with each bump on the taxiway that the plane hits.

The Volumetric Shut off it seems to me (would have to get out my old books and dust up a bit) was nothing more then an arrow on the gauge that could be set to the pounds per tank to automate shutting the tank valves. These are only available on the newer aircraft and like any other fancy unnecessary item would break all the time, and you were better off to fuel manually and never even bother with them to begin with (push the arrow to the top of the gauge). I mean how hard is it to watch the tank levels and snap down a button when the arrow hits 9K on each wing tank and 5K in the center anyway, by way of example?

I think that zaphods busted wing picture was a stuck fuel valve, where the fuel is trying to pump into a valve that is stuck shut until the pressure builds so high in the pipe that it structurally damaged the plane, but correct me if I am wrong there zaphod.

It also sounds like you feel that there are more tanks on some of these aircraft then there are, as an example there are 3 on a 737, unless it has an aux tank, not multiple ones in each wing. If the wing tanks are in fact actuality broken into multiple tanks per wing then there is no way for the fueler to control them, they simply flow one into the next, or the fuel is transferred by pumps that are not under the fueler’s control. But I can assure you there are three gauges and three shut offs on a 737.

So no offence but this does not sound like a serious concern to me. Besides if this was such a danger there would be aircraft popping at the gate while being fueled all the time, and I cannot say that I have ever heard of this happening once.

Originally posted by elpasys

Please read between the lines of the official report:

"The VSO (volumetric shutoff) will also shut the valves when fuel enters the tanks if a fuel tank is overfilled. While the accident airplane was being fueled at JFK the fuel system's automatic VSO activated"

[due to fuel weathering (nucleate boiling)] (the unspoken words)

"before the fuel tanks were full. A mechanic overode the safety system and finished fueling manually."

"TWA Flight 800 was schedulded to depart JFK (New York, New York, USA) for Charles de Gaulle Airport (CDG, Paris, France) about 19:00; however, the flight was delayed"

[1.2 hour] [due to fuel weathering (nucleate boiling)]. [Official:] (the unspoken words)

"a disabled piece of ground equipment (a fleet service vehicle was blocking the accident airplane at the gate) and concerns about a suspected passenger/baggage mismatch (the missing passenger was on board the whole time)."

To me this means that the crew wanted say, 10K of gas, but because of the density of the gas being higher then normal due to temperature, they could only fit 9K and had to force the poundage on the plane by fueling manually since the gauges want to shut off when it hits that arrow. The part of this that makes no since to me is that you seem to assume that you can squeeze 10 pounds of crap into a 5 pound bucket and I am sorry to report that if you try with on a commercial airliner, your going to be on the phone with the fire department explaining why you have a fuel spill at your gate. Now I am not a mechanic and perhaps there is some way to make this happen, but I have never heard of it.

So yeah it’s a fuel delay in that they could not get the fuel load onto the plane that the flight crew requested, or a gauge was sticking and would not let them top off the tank. To be honest a 1.2 hour delay sounds a lot more like a fueler over-fueled a tank and it had to be de-fueled, which is a pretty slow process since the plane does not have the large pumps that the truck does to suck the fuel back out of the tanks. The only other thing that takes that long is to transfer fuel from the center to the wings.

As to the rest, that is SH that happens at an airport, nothing unusual there, equipment breaks down in the pushback path of the aircraft, and the baggage/passenger list has to match up, stuff like that.

I also want to put in here that the reason that a plane officially takes a delay and the real reason are not always exactly the same. It used to be a trick, if the deck crew allowed you to do it, that to get around a delay, you could push back the plane a few feet to finish loading bags or whatever you had to finish, and it would get charged as a taxi delay and does not get counted against the airlines on-time records, as an example.





[edit on 10/22/2005 by defcon5]

elpasys


why do you keep posting , when the `evidence` you supply is disproved from the very same links you supply???

defcon5,

Anti-static additives or static dissipator additives are polar.

Entropy is generated when dissimilar surfaces move across each other, for example, when fuel moves through a pipe, hose, valve, or fine filter. The entropy production rate during filtration, mixing [Gibbs Paradox of Entropy of Mixing], cavitation and friction is very sensitive to the concentration of entropy (fermions, or polar additives) in fuel (positive feedback mechanism). Military jet fuels and international Jet A-1 require the use of an additive to increase the electrical conductivity of the fuel. Conductivity improving additives are also called anti-static additives or static dissipator additives.

"It was found that there is a relationship between concentration polarization and entropy generation during ultrafiltration. Moreover, minimum entropy production favors a reduced level of contrentation polarization. During ultrafiltration the fuel has tendency to undergo irreversible procesess (i.e. degradation or decay) and thereby increase the entropy of the system (aircraft)." [Parvatiyar M.G. Entropy Generation in Ultrafiltration Processes. Journal of Membrane Science 144, 1998, 125-132. www.elsevier.com... , (payable).]

A large entropy generally implies small predictability (i.e. chaos). At higher entropies the fuel-system enters deeply into the instability region. This implies that there is a quick expansion (degradation) of the fuel which leads the fuel-system in the gas region. High entropy can result in fuel system vapor lock or explosion.

For lower entropies the fuel never hits the gas region and bubbles formation from the liquid state.

Aviation fuel filters producer's site
Section: Aerospace, Defense, Marine:
Entropy is never mentioned.

Section: Natural Gas:
Natural Gas Liquids
"The tendency to maximize the entropy is countered by the tendency to minimalize the interlial energy."

The VSO (volumetric shutoff) will also shut the valves when fuel enters the tanks if a fuel tank is overfilled. While the accident airplane (TWA 800) was being fueled at JFK the fuel system's automatic VSO activated due to fuel weathering (nucleate boiling) before the fuel tanks were full.

Edit: cosmetics

[edit on 24-10-2005 by elpasys]

Look man, a hydrant truck is basically a large pump and a filter, on a custom made Ford F-250, which is hooked to an underground fuel pit system that runs to the tank farm. The fuel that is moving through the pipelines and the truck would have a similar issue if there was any truth to this accusation whatsoever. We certainly do not have to wait to be moving the truck around between flights to allow the static in the lines, pump, and filter to dissipate, and we did not keep the truck grounded when moving from flight to flight, or even when just driving aimlessly around the airport waiting on a flight. Sometimes you barely had enough time between flights to store your hoses and run your paperwork to the flight deck, let alone waiting for static to dissipate. If what you’re saying is true, then why have the same trucks been running around that airport for over 20 years and never a single one has had such an incident. Yeah the trucks break down and stuff like that, but certainly one has never spontaneously caught fire or exploded.

As to the VSO, again, if there was such a failsafe system to stop overfilling, beyond what I already stated, then why have I seen so many fuel spills in my lifetime (as a ramp agent, lead agent, supervisor, and fueler)? If this was such a great, functional, usable, system that all aircraft had, I should have never seen a single spill in the years I worked out there (this magical shut off should have prevented it, at least in what you seem to think the system does). We would get spills probably about once a month; usually it’s only a small spill, like 5 to 10 gallons (as you can usually hear and see the spill when it happens, and drop the deadman). This is generally because TIA (TPA) is renowned for having cheap AV-Gas, so a lot of flights top off while there, and I have yet to meet the pilot that walked into flight ops and did not want to uplift the fuel load by at least an extra 2K pounds of gas. Humorously it’s always 2K.

When you shut off a tank, the gas does not immediately stop flowing to it, but it rolls sometimes a few hundred pounds before it stops, and when you’re already pushing the top of the tank that sometimes pushes it over the edge. While fueling you hold onto a deadman line (emergency pump shutoff), and usually on the last tank (they fill up at different rates) you “kick the pit” (releasing the 6 inch ground line from the fuel pit) rather then close the tank, but keep the deadman pulled (the pump running) for a minute or two. This allows the fuel in the 6 inch ground hose and the 4 inch aircraft hose to discharge the fuel inside them, or the hoses retain pressure and are impossible to put away (hard as rock) besides being very heavy to lift (especially the ones on the wing above your head, which can weigh hundreds of pounds more then normal). Now there is still gas in the whole system, or we would have to re-prime the pump, but the pressure is released from them. Anyway, sometimes these little amounts of extra gas are enough to cause a small fuel spill (small being several gallons), and like I said it happens all the time.

Then lets not even get into the whole aspect of how often you would open the fuel panel and crap was marked INOP, usually meaning we would have to fuel by “drip-stick” (like a oil dipstick that unscrews from under the tanks, and it would shoot out a small amount of fuel when the specified amount was hit, basically a MAJOR PAIN in the ARSE). Lets also not bring up the times that the gauges are misreading. As someone else mentioned here, stuff on planes is not always in working order, there is always a list of “features” on every plane that are INOP at any given time, but the aircraft is still usable. Stuff like this is fixed when it gets to a major maintenance facility since none of it is considered significant enough to be “no-fly” items, and individual stations do not maintain the parts to fix everything on every aircraft.

The whole system of hydrant fueling is very similar to pumping water for a fire department, even the hose sizes are the same. So I wonder why the firefighters are not getting shocked all the time from all that water that is flowing through their hoses, hm?


[edit on 10/24/2005 by defcon5]

Concorde Flight 4590, the last refueling:
"An innordinate amount of fuel had escaped the tanks". More

Official: "Replace a part in a thrust-reverser. Mechanics took half an hour to complete the repairs."

Conclusion.
Exergy concept in aviation is a distinct discipline, because of its interdisciplinary character as the confluence of energy, environment and sustainable development.. Exergy analysis can reveal how is possible to design more efficient aircraft. We cannot continue in our present methods of using the aiplanes. An organism (or an aircraft) cannot live in a medium of its own waste products (entropy = wasted energy). Fuel tank explosions occur because the aicraft isn’t forcefully engineered to prevent them. Stopping them will require that aviation engineers change the system thinking and the way they operate the aircraft.

Rather then trying to impress us with your vocabulary, why not just answer the questions I have posted to you?

These are valid questions from a real world perspective, from someone that has worked in the field, not speculation from someone with gawd knows what background that are obviously worded to try and impress everyone here with some deep scientific insight.

Originally posted by elpasys
Official: "Replace a part in a thrust-reverser. Mechanics took half an hour to complete the repairs."

And this has exactly what to do with the fuel system? Thrust reversers are simply a system to send the engine thrust forward instead of back. On a DC-9/MD-80 they are just plates that snap over the back end of the engine and make the air travel forward. If they are attached to any system, it’s hydraulic, not fuel related.

This by itself leads me to believe that you know JACK about aircraft.



[edit on 10/24/2005 by defcon5]

Hi defcon5,

I'm living and working (small business) in Warsaw, Poland. What can I do for you, for aviation, and for the flying - society, in this schismatic and schizophrenic situation?

It has allready been proven , on links you have supplied that concord crashed because of debris on teh runway.


nothing to do with any fueling system

Originally posted by Harlequin
It has allready been proven , on links you have supplied that concord crashed because of debris on teh runway.

nothing to do with any fueling system

"Continental Airlines has rejected the blame for causing a Concorde supersonic jet to crash near Paris leading to the deaths of 113 people."

More

Originally posted by Harlequin
concord crashed because of debris on teh runway.

"A former head of the Concorde division at France's Aerospatiale has been placed under judicial investigation over the fatal July 2000 crash of a Concorde jetliner near Paris. . .

He was placed under formal investigation, a first step to possible charges, for involuntarily causing death and injury.

Perrier was head of the Concorde programme at Aerospatiale, now part of the European Aeronautic Defence and Space Company, from 1978 to 1994. He is suspected to have known about a design fault in the wing since 1979 and an incident involving a Concorde in Washington, but failed to rectify it.

A French accident inquiry concluded in December that the prime cause of the crash was a titanium strip which had fallen off a US Continental Airlines plane on to the runway. However a separate experts' report sent to the investigating magistrate in August, seen by AFP, also said the design fault was a contributing factor.

It made serious criticisms of Aerospatiale and two French official bodies for failing to react appropriately to the problem."


More: "Former Concorde official probed over fatal Paris crash"

gosh your very good at hacking apart articles just to print what you want to :

The titanium strip shredded one of the Concorde's tyres as the supersonic airliner took off, sending heavy chunks of rubber through a fuel tank located in a wing and setting it alight.

taken from your link : www.turkishpress.com...

and `design fault` which you keep mentioning:

The official 237-page report also highlighted a "serious fault" in the design of Concorde, whose tanks had insufficient protection from debris

protection from debris.

taken from your link:edition.cnn.com...


oh and about continental:

According to Reuters, Salvat said a U.S. probe had shown the replacement titanium alloy strip fitted to the DC-10 had not been authorized by the U.S. Civil Aviation authorities.

He said Continental had failed to respect rules governing metal fixtures used in building aircraft, and that the characteristics of the strip "played a major role in the process of cutting the Concorde's tire."

AND

An international arrest warrant was issued against Taylor, who allegedly fitted the non-standard titanium strip to the US airline's DC-10. He failed to show up in France for questioning on June 17 as required

from the same links you supplied.


As said many MANY times , it was a metal strip which caused the accident , with a design fault which could have prevented the fuel leakage BUT NOT THE TYRE DAMAGE.

Originally posted by Harlequin

As said many MANY times , it was a metal strip which caused the accident, .

"Concorde irrefutable photographic proof of pre-flight sabotage. . .
the small red circle which shows flames from the wheelbay being sucked
into the the open auxiliary air intake of No 2 engine, which cautgh fire
eleven seconds AFTER the initial explosion in fuel tanks 6 or 2."
More: www.joevialls.co.uk...

or : vialls.com...

ROFL

you use joe viallis as `evidence`

Entropy at a helicopter see:
www.ntsb.gov...

Oh please. A helicopter is 10,000 parts spinning in different directions held together by prayer. lol

Originally posted by elpasys
Entropy at a helicopter see:
www.ntsb.gov...

You did read the report?

In the abstract it blames blade actuators... (I assume blade pitch)


Maybe this user is just joking and winding everyone up with this thread?

CASA Urgent AD: Bell Helicopter
"Transport Canada has advised that inadequate electrical grounding of the fuel boost pump and the fuel drain solenoid valve, combined with fuel hoses contact, could cause arcing in the main fuel cell which may in turn cause an explosion and resultant fire."

More: Aero-News, Issue 72/02, December 01, 2005, www.aero-news.net...

And bad wiring, chafing, and sparking have WHAT exactly to do with entropy? I didn't realize that human error was part of entropy.