FAA Fix For Fuel Tank Explosions
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Most of you are missing the point. If the FAA say that you should "inert" your tanks and you don't do it then, come any form of incident involving a fuel tank (it doesn't even have to be an explosion) the lawyers will slaughter the airline concerned. They finished off Swissair good style.
The seven years of grace are equally useless because if you have an accident in that period the lawyers and the juries are going to say - "Well you could have done it but you chose to wait."
The seven years of grace are equally useless because if you have an accident in that period the lawyers and the juries are going to say - "Well you could have done it but you chose to wait."
It is not only the 747 which has suffered a fuel tank explosion, although it was the most newsworthy example. This from http://www.b737.org.uk/fuel.htm
“To date, two 737's, 737-400 HS-TDC of Thai Airways on 3 Mar 2001 and 737-300 EI-BZG operated by Philippine Airlines on 5 Nov 1990 have been destroyed on the ground due to explosions in the empty centre fuel tank. In 1996, the very high profile TWA 800, a 747-100 mid-air explosion was also determined to have originated in an empty centre fuel tank.
The common factor in all three accidents was that the aircraft had empty center fuel tanks. However even an empty tank has some unusable fuel which in the heat will evaporate and create an explosive mixture with the oxygen in the air. These incidents, have sparked (sic) debate about fuel tank inerting. This is universally considered to be the safest way forward, but very expensive and possibly impractical. The NTSB recommended many years ago to the FAA that a fuel tank inerting system be made mandatory, but the FAA have repeatedly rejected it on cost grounds.
Boeing is now developing a Flammability Reduction System (FRS), this uses bleed air ducted to air separation modules that remove about 50% of the oxygen. This is then mixed with air from a nitrogen generating system and sent to the fuel tank to give almost inert, nitrogen rich, fuel tank air. The FAA Technical Center has determined that an oxygen level of 12% is sufficient to prevent ignition, this is achievable with one module on the 737 but will require up to six on larger aircraft.
Boeing flight tested a 747-400 in summer 2003 with a prototype FRS, data from which will be used to define the production system. A scaled down version of the 747 system was due to be installed on a 737-NG for flight testing in 2004. Boeing will then fit the FRS into some 737 & 747's for in-service evaluation after certification. A 737-200 has been also acquired by the FAA Technical Center for conversion into a fuel tank inerting system testbed.
In Feb 2004 the FAA announced a NPRM that will require a fuel inerting system to be installed on all airliners by 2011.”
Given that this is probably something that could affect any airliner eventually, I don’t see why anybody should object to the FAA insisting on a fuel inerting system. Especially on new airliners since they can design in the system at mimimal cost compared to a retrofit. Also, a 7 year notice period is hardly draconian and merely reflects the rarity of the problem.
“To date, two 737's, 737-400 HS-TDC of Thai Airways on 3 Mar 2001 and 737-300 EI-BZG operated by Philippine Airlines on 5 Nov 1990 have been destroyed on the ground due to explosions in the empty centre fuel tank. In 1996, the very high profile TWA 800, a 747-100 mid-air explosion was also determined to have originated in an empty centre fuel tank.
The common factor in all three accidents was that the aircraft had empty center fuel tanks. However even an empty tank has some unusable fuel which in the heat will evaporate and create an explosive mixture with the oxygen in the air. These incidents, have sparked (sic) debate about fuel tank inerting. This is universally considered to be the safest way forward, but very expensive and possibly impractical. The NTSB recommended many years ago to the FAA that a fuel tank inerting system be made mandatory, but the FAA have repeatedly rejected it on cost grounds.
Boeing is now developing a Flammability Reduction System (FRS), this uses bleed air ducted to air separation modules that remove about 50% of the oxygen. This is then mixed with air from a nitrogen generating system and sent to the fuel tank to give almost inert, nitrogen rich, fuel tank air. The FAA Technical Center has determined that an oxygen level of 12% is sufficient to prevent ignition, this is achievable with one module on the 737 but will require up to six on larger aircraft.
Boeing flight tested a 747-400 in summer 2003 with a prototype FRS, data from which will be used to define the production system. A scaled down version of the 747 system was due to be installed on a 737-NG for flight testing in 2004. Boeing will then fit the FRS into some 737 & 747's for in-service evaluation after certification. A 737-200 has been also acquired by the FAA Technical Center for conversion into a fuel tank inerting system testbed.
In Feb 2004 the FAA announced a NPRM that will require a fuel inerting system to be installed on all airliners by 2011.”
Given that this is probably something that could affect any airliner eventually, I don’t see why anybody should object to the FAA insisting on a fuel inerting system. Especially on new airliners since they can design in the system at mimimal cost compared to a retrofit. Also, a 7 year notice period is hardly draconian and merely reflects the rarity of the problem.
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I have read endlessly on the TWA800, and I have no doubt in my mind that this was a huge military 'cock-up' leading to the downing of a 747 and countless innocent lives.
Concorde was removed from service days after the paris crash due to a freak sequence of events. 747's still litter our skies, harnessing this apparently lethal fault. Its all nonsense.
While I agree there is a definate 'issue' with centre tanks, they certainly shouldn't be linked IN ANY WAY to the TWA incident because the aircraft was shot down. As the yanks say, PERIOD!
Concorde was removed from service days after the paris crash due to a freak sequence of events. 747's still litter our skies, harnessing this apparently lethal fault. Its all nonsense.
While I agree there is a definate 'issue' with centre tanks, they certainly shouldn't be linked IN ANY WAY to the TWA incident because the aircraft was shot down. As the yanks say, PERIOD!
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When does it happen?
Seems to be on - or after a spell on - the ground, that this type of explosion has occurred. Maybe there wasn't a spark at all.
After the tank empties in flight there is much less chance of an environmental overheat (although I did collect a HP Victor from a check in St Athan once and had blisters on the bomb bay tank afterwards from a loose hot air duct...)
Why not then start with a ground based system to fill intentionally empty tanks with nitrogen after landing?
This could involve a nitrogen truck and the mod would be addition of a (Schrader) valve and a bit of tubing to the tank. In this way much of the engineering work and costs might be saved.
After the tank empties in flight there is much less chance of an environmental overheat (although I did collect a HP Victor from a check in St Athan once and had blisters on the bomb bay tank afterwards from a loose hot air duct...)
Why not then start with a ground based system to fill intentionally empty tanks with nitrogen after landing?
This could involve a nitrogen truck and the mod would be addition of a (Schrader) valve and a bit of tubing to the tank. In this way much of the engineering work and costs might be saved.
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Well said FC. The need to replenish the nitrogen once into flight may be obviated by the lower environmental temperatures. And there's no weight penalty to a ground-based system.
Separately, consider that inerting could be a useful protection against the remote possibility of being hit by a MANPAD. The DHL over Baghdad took the warhead in a full tank. Had it been half full, it might well have gone up.
Separately, consider that inerting could be a useful protection against the remote possibility of being hit by a MANPAD. The DHL over Baghdad took the warhead in a full tank. Had it been half full, it might well have gone up.
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Ugh, conspiracy theories again.
Someone mentioned comparing the fuses of TWA800 with a "DC 9 that crashed in the mediterranean". (Itavia, perhaps?)
There's a lot more compelling evidence for that DC-9 being shot down then there is for TWA 800; and even so, I doubt we'll ever conclusively know the answer in the Ustica case.
When that Itavia flight went down, the official statement that it was a bomb was released very quickly, in the days following the accident, and three weeks before the news broke of the Libyan MiG-21 wreckage in Calabria (which occurred sometime before).
When TWA 800 went down, the investigating authorities were very slow to release their findings; yet days after the event, the news that the center tank was on fumes and 50-60 degrees C was included (without hypothesis) in the journalist's reports.
Missiles do knock down airliners, and we have plenty of cases where they do, including missiles fired by the US. The evidence for TWA 800 is just weak; on the other hand, a fuel tank explosion, given the conditions, makes a lot of sense: sure it's a rare event, but thank God we don't have common events bringing down planes very much.
Comparing the Concorde to these things is ridiculous, given the very rare usage of the concorde. Given the rate of failures, if the concorde were as common as the 737 (with its miysterious rudder issues), then several times a week they'd be suffering damage from tire blowouts, including fuel leaks. And once a month there'd be a horrible crash.
Most big explosions happen in Hollywood. Fuel tanks are only at risk for catastrophic explosions when the quantity of fuel remaining (and the heat) is such to create an ideal fuel-air mixture for a spark to set off. A cheap way to remove the oxygen from those tanks is a good thing, even if it's a remote possibility.
Oh and the Swissair MD-11 fire pretty much killed MD-11 production.
Someone mentioned comparing the fuses of TWA800 with a "DC 9 that crashed in the mediterranean". (Itavia, perhaps?)
There's a lot more compelling evidence for that DC-9 being shot down then there is for TWA 800; and even so, I doubt we'll ever conclusively know the answer in the Ustica case.
When that Itavia flight went down, the official statement that it was a bomb was released very quickly, in the days following the accident, and three weeks before the news broke of the Libyan MiG-21 wreckage in Calabria (which occurred sometime before).
When TWA 800 went down, the investigating authorities were very slow to release their findings; yet days after the event, the news that the center tank was on fumes and 50-60 degrees C was included (without hypothesis) in the journalist's reports.
Missiles do knock down airliners, and we have plenty of cases where they do, including missiles fired by the US. The evidence for TWA 800 is just weak; on the other hand, a fuel tank explosion, given the conditions, makes a lot of sense: sure it's a rare event, but thank God we don't have common events bringing down planes very much.
Comparing the Concorde to these things is ridiculous, given the very rare usage of the concorde. Given the rate of failures, if the concorde were as common as the 737 (with its miysterious rudder issues), then several times a week they'd be suffering damage from tire blowouts, including fuel leaks. And once a month there'd be a horrible crash.
Most big explosions happen in Hollywood. Fuel tanks are only at risk for catastrophic explosions when the quantity of fuel remaining (and the heat) is such to create an ideal fuel-air mixture for a spark to set off. A cheap way to remove the oxygen from those tanks is a good thing, even if it's a remote possibility.
Oh and the Swissair MD-11 fire pretty much killed MD-11 production.
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The TWA 800 accident actual cause!
There were No missiles and No bombs! The Center Wing Fuel Tank Explosion was not the initial cause of the accident!
TWA 800 encountered a strong aircraft wake vortex at 20:31:12! (Radar evidence and Boston Air Traffic Control's communication to the preceding aircraft, proves the existence of the aircraft traffic!
A 13.5 foot section of the keel beam was torn out of the aircraft's structure, along with the two air conditioning machines, and the first two bulkheads of the center wing fuel tank! These items, along with others, fell into the "Red" debris zone. No items in the "Red" zone exhibited any soot, smoke, or explosive damage!
The Flight Data Recorder (FDR) continued to record until 20:31:20 at which time the FDR and both cockpit clocks stop! The time of the actual explosion, eight seconds after the initial break-up of the structure!
There was a completely stable air mass that evening, the ocean was as calm as a mill pond, (first clue!) In these weather conditions there is little or no dissipation of the preceding aircraft's vortices, or the fuel vapors exiting from TWA 800's wing tip vents!
At the time of the explosion the wing tip vent fuel was ignited and these instantaneous flame fronts streaked down the aircraft's flight path towards the ground! Thus, the eye witness reports of, "missile trails"!
I have copies of both the original and the NTSB modified FDR charts, which I have enlarged to show the radical deviations in all systems at 20:31:12, the NTSB's "End of Data" line, which is the time of the initial aircraft turbulence encounter!
The NTSB claim that the continuation of the FDR chart is from another AA flight is not correct. There is no three inch tape separation to indicate two different flight recordings! The TWA 800 FDR tape is continuous!
If this accident's real cause had not been covered up, the AA 587 accident may not have occurred! (An increase in aircraft separation standards would probably have been ordered.)..
This accident should alert the "industry" to the high inertia problem involving large, massive, aircraft structures, i.e., the Boeing 747 and now the Airbus 380!
There were No missiles and No bombs! The Center Wing Fuel Tank Explosion was not the initial cause of the accident!
TWA 800 encountered a strong aircraft wake vortex at 20:31:12! (Radar evidence and Boston Air Traffic Control's communication to the preceding aircraft, proves the existence of the aircraft traffic!
A 13.5 foot section of the keel beam was torn out of the aircraft's structure, along with the two air conditioning machines, and the first two bulkheads of the center wing fuel tank! These items, along with others, fell into the "Red" debris zone. No items in the "Red" zone exhibited any soot, smoke, or explosive damage!
The Flight Data Recorder (FDR) continued to record until 20:31:20 at which time the FDR and both cockpit clocks stop! The time of the actual explosion, eight seconds after the initial break-up of the structure!
There was a completely stable air mass that evening, the ocean was as calm as a mill pond, (first clue!) In these weather conditions there is little or no dissipation of the preceding aircraft's vortices, or the fuel vapors exiting from TWA 800's wing tip vents!
At the time of the explosion the wing tip vent fuel was ignited and these instantaneous flame fronts streaked down the aircraft's flight path towards the ground! Thus, the eye witness reports of, "missile trails"!
I have copies of both the original and the NTSB modified FDR charts, which I have enlarged to show the radical deviations in all systems at 20:31:12, the NTSB's "End of Data" line, which is the time of the initial aircraft turbulence encounter!
The NTSB claim that the continuation of the FDR chart is from another AA flight is not correct. There is no three inch tape separation to indicate two different flight recordings! The TWA 800 FDR tape is continuous!
If this accident's real cause had not been covered up, the AA 587 accident may not have occurred! (An increase in aircraft separation standards would probably have been ordered.)..
This accident should alert the "industry" to the high inertia problem involving large, massive, aircraft structures, i.e., the Boeing 747 and now the Airbus 380!
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I stand by my comments
The only difference in how I feel about this subject is that one year ago I didn't fly the 747-200.
This year I'm qualified on the 747-200 and while I realize that doesn't make me an expert on her systems I can honestly say that I've received instruction from and fly regularly with guys who have been flying this airplane for 30 years--some are ex-military--and even they think TWA 800 was brought down by something besides a fuel tank explosion.
How's that for a run-on sentence? No time to edit right now.
I don't believe I've ever advanced a terrorist or military theory. It could've been either (or both?!). I'm just saying I don't believe there to be a design flaw in the fuel system.
A design flaw *will* repeat itself given time and cycles. The 747 has both.
It's a fantastic design.
This year I'm qualified on the 747-200 and while I realize that doesn't make me an expert on her systems I can honestly say that I've received instruction from and fly regularly with guys who have been flying this airplane for 30 years--some are ex-military--and even they think TWA 800 was brought down by something besides a fuel tank explosion.
How's that for a run-on sentence? No time to edit right now.
I don't believe I've ever advanced a terrorist or military theory. It could've been either (or both?!). I'm just saying I don't believe there to be a design flaw in the fuel system.
A design flaw *will* repeat itself given time and cycles. The 747 has both.
It's a fantastic design.
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I thoroughly agree.
I would like to know how many cycles the worlds inventory of 747-200's have done. If it had been a design flaw it would have happened again, and possibly again and again.
I have got my theory of the aircraft being 'un-intendidly' <---- is that even a word
, shot down due to the governments behaviour the months after the accident.
Evidence went missing at crucial times etc, there was a massive cover up probably resulting in huge pay offs and secrecy contracts etc.
As I said that is only my humble opinion, the actual cause may differ, but it certainly wasn't fuel!
I would like to know how many cycles the worlds inventory of 747-200's have done. If it had been a design flaw it would have happened again, and possibly again and again.
I have got my theory of the aircraft being 'un-intendidly' <---- is that even a word
, shot down due to the governments behaviour the months after the accident.Evidence went missing at crucial times etc, there was a massive cover up probably resulting in huge pay offs and secrecy contracts etc.
As I said that is only my humble opinion, the actual cause may differ, but it certainly wasn't fuel!
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For the conspiracy theorists - think about this.
SAMs very rarely cause an aeroplane to explode into lots of little bits the way that TWA 800 did. The typical SAM (or indeed air to air missile) relies upon a proximity fuse and warhead fragmentation and schrapnel to slice off big chunks of the airframe, causing the aeroplane (or what is left of it) to fall out of the sky. The result is that the debris is generally found to be in large pieces.
TWA 800 disintegrated in lots of little bits - the debris being much more compatible with an on-board rather than external explosion. So unless a bomb was on board the aeroplane then it was some part of the aeroplane itself (i.e. centre fuel tank pumps and associated vapour) which caused the explosion in the first place.
SAMs very rarely cause an aeroplane to explode into lots of little bits the way that TWA 800 did. The typical SAM (or indeed air to air missile) relies upon a proximity fuse and warhead fragmentation and schrapnel to slice off big chunks of the airframe, causing the aeroplane (or what is left of it) to fall out of the sky. The result is that the debris is generally found to be in large pieces.
TWA 800 disintegrated in lots of little bits - the debris being much more compatible with an on-board rather than external explosion. So unless a bomb was on board the aeroplane then it was some part of the aeroplane itself (i.e. centre fuel tank pumps and associated vapour) which caused the explosion in the first place.
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The technology used the create these new onboard nitrogen inerting systems is Hollow Fiber Membrane technology.
Here's a link to an explanation of this technology.
IGS Generon System
With all of the discussion of missiles and terrorism in this thread, no one has mentioned that this technology makes airliners safer in today's higher threat environments. The US military has been using nitrogen inerting in aircraft since WWII, to help prevent fires and explosions when fuel tanks are hit.
Here's a link to an FAA article on this technology:
FAA Fuel tank inerting
Here's a quote from this article that illustrates the protection offered to an aircarft that's being fired upon:
This technology is a good thing, both to prevent future fuel tank explosions, and to help you survive if someone fires on your aircraft.
Here's a link to an explanation of this technology.
IGS Generon System
With all of the discussion of missiles and terrorism in this thread, no one has mentioned that this technology makes airliners safer in today's higher threat environments. The US military has been using nitrogen inerting in aircraft since WWII, to help prevent fires and explosions when fuel tanks are hit.
Here's a link to an FAA article on this technology:
FAA Fuel tank inerting
Here's a quote from this article that illustrates the protection offered to an aircarft that's being fired upon:
What is a fuel tank inerting system?
An inerting system replaces the oxygen in the fuel tank with an inert gas such as nitrogen, preventing the potential ignition of fuel vapor.
Inerting systems have been used on military aircraft since World War II. Until now, inerting of the fuel tanks has been used to minimize combat explosions and battle damage. On high-speed airplanes such as the XB-70, an inerting system was used to prevent ignition of the fuel due to the heating effects of supersonic speeds.
Many different techniques have been used in the inerting systems on military aircraft. On World War II-era airplanes, engine exhaust was typically used to produce the inert gas. More recently, nitrogen has been used to render the fuel tank inert. Various techniques exist for separating nitrogen from air for use in inerting, the simplest and most reliable being the membrane technology that is used in the FAA-developed inerting system prototype.
An inerting system replaces the oxygen in the fuel tank with an inert gas such as nitrogen, preventing the potential ignition of fuel vapor.
Inerting systems have been used on military aircraft since World War II. Until now, inerting of the fuel tanks has been used to minimize combat explosions and battle damage. On high-speed airplanes such as the XB-70, an inerting system was used to prevent ignition of the fuel due to the heating effects of supersonic speeds.
Many different techniques have been used in the inerting systems on military aircraft. On World War II-era airplanes, engine exhaust was typically used to produce the inert gas. More recently, nitrogen has been used to render the fuel tank inert. Various techniques exist for separating nitrogen from air for use in inerting, the simplest and most reliable being the membrane technology that is used in the FAA-developed inerting system prototype.
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"Has this been brought in to prevent fuel tank explosions OR to help towards preventing another 747 being blown out of the sky."
Would that be accidentally or intentionally, then?
Would that be accidentally or intentionally, then?
There is much enlightening info on this topic.
A certain book written about the TWA tragedy referred:
1) to the 'fact' that the FBI (for the first time after an aircraft accident?) rode on the first boats which took law enforcement people to the crash location.
2) that the debris was tightly sealed in a building with unusually high security to prevent access. All accident investigations require some security-but this much?
3) that some sort of missile (propellant?) residue was found on some cabin seats or other debris.
Is any of this true, or none of it true? If some of it is, then why the FBI involvement and such high security, unless a terrorist group secretly claimed to have done it, or a military missile somehow tracked the plane and had the range to hit it? Maybe a missile impact would have produced different damage, but there are so many bizarre facts connected with this case. Even an AF Reserve helicopter pilot with a squadron on Long Island claimed to have seen a missile streak towards the 747. He was interviewed by the media, but he seems to have said nothing after the initial appearance. Is any of the true? I have no idea if there really was some sort of conspiracy (clearly this happens only in the US...let's forget the charges made "over there" or "over here" about Diana's death in the Paris tunnel....), but whether any such proof could ever be released to the media, is very unlikely.
About nitrogen inerting in fuel tanks, there was one known such fatal accident among tens of thousands of flights aboard US-built aircraft per year. How would the FAA's almost secret, safety "cost/benefit" analysis see such a modest loss of life as justification for the huge expense, unless it is a huge attempt (by more than the FAA alone) to keep public/media attention from focusing on any OTHER cause? To divert public attention c o u l d be the main priority here. To hit two birds with one stone, attention can be diverted while time goes by and the public forgets about nitrogen inerting thingies, which might cost airlines nothing. It might only cost the US airlines money.
Anyway, with politics and foreign relations always the highest priority, which even help determine which foreign airlines are deemed safe enough to fly into the US (create the correct paperwork and don't seriously insult the State Department in certain contexts), the administrators might not want to push any bankrupt airline over the edge; these top administrators are all political appointees, as are the heads of the DOT, FBI and Justice Departments etc. The FAA once had a former Thunderbird pilot as the man "in-charge" (
), to put it very loosely.
A certain book written about the TWA tragedy referred:
1) to the 'fact' that the FBI (for the first time after an aircraft accident?) rode on the first boats which took law enforcement people to the crash location.
2) that the debris was tightly sealed in a building with unusually high security to prevent access. All accident investigations require some security-but this much?
3) that some sort of missile (propellant?) residue was found on some cabin seats or other debris.
Is any of this true, or none of it true? If some of it is, then why the FBI involvement and such high security, unless a terrorist group secretly claimed to have done it, or a military missile somehow tracked the plane and had the range to hit it? Maybe a missile impact would have produced different damage, but there are so many bizarre facts connected with this case. Even an AF Reserve helicopter pilot with a squadron on Long Island claimed to have seen a missile streak towards the 747. He was interviewed by the media, but he seems to have said nothing after the initial appearance. Is any of the true? I have no idea if there really was some sort of conspiracy (clearly this happens only in the US...let's forget the charges made "over there" or "over here" about Diana's death in the Paris tunnel....), but whether any such proof could ever be released to the media, is very unlikely.
About nitrogen inerting in fuel tanks, there was one known such fatal accident among tens of thousands of flights aboard US-built aircraft per year. How would the FAA's almost secret, safety "cost/benefit" analysis see such a modest loss of life as justification for the huge expense, unless it is a huge attempt (by more than the FAA alone) to keep public/media attention from focusing on any OTHER cause? To divert public attention c o u l d be the main priority here. To hit two birds with one stone, attention can be diverted while time goes by and the public forgets about nitrogen inerting thingies, which might cost airlines nothing. It might only cost the US airlines money.
Anyway, with politics and foreign relations always the highest priority, which even help determine which foreign airlines are deemed safe enough to fly into the US (create the correct paperwork and don't seriously insult the State Department in certain contexts), the administrators might not want to push any bankrupt airline over the edge; these top administrators are all political appointees, as are the heads of the DOT, FBI and Justice Departments etc. The FAA once had a former Thunderbird pilot as the man "in-charge" (
), to put it very loosely.
Last edited by Ignition Override; 21st Feb 2005 at 03:40.
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The Delay for Inerting
As Dagger Dirk pointed out back on page two of this thread, the FAA, sometime in the latter half of 2004, resiled from any inert gas solution for tank flammability - at least for a number of years to come.
My question is: "Does anybody have a reference to that delay (preferably an FAA online document or alternatively a news article covering that delay and the other program that were to be delayed due to economic astringencies)????
UNC
My question is: "Does anybody have a reference to that delay (preferably an FAA online document or alternatively a news article covering that delay and the other program that were to be delayed due to economic astringencies)????
UNC
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. . . . .Boeing Center Tank Design Flaw.
I'm a Boeing driver but I am no fan of Boeing center tank design. As mentioned earlier, besides the TW800 center tank explosion, there are two well documented B737 center tank explosions.
The Boeing center tank design flaw is that the center tank pumps are inside the center tank. Because the center tank fuel is used before the main tank fuel there is always the chance of having the center tank pump(s) still running long after the tank is empty. When pumps run dry they overheat. Automatic shutoff switching or thermal overheat cut-off switching can be faulty.
The superlative center tank pump design dates back to the mid 50s when the DC8 was designed. The visionary Mr. Douglas had positioned the center tank fuel pump inside the adjacent main tank, a fail safe design that provides continuous cooling in case the pump doesn't get shut off when the center tank goes dry.
Repositioning Boeing center tank fuel pumps into an adjacent main tank would preclude the greatest volatility of center tank explosions.
The Boeing center tank design flaw is that the center tank pumps are inside the center tank. Because the center tank fuel is used before the main tank fuel there is always the chance of having the center tank pump(s) still running long after the tank is empty. When pumps run dry they overheat. Automatic shutoff switching or thermal overheat cut-off switching can be faulty.
The superlative center tank pump design dates back to the mid 50s when the DC8 was designed. The visionary Mr. Douglas had positioned the center tank fuel pump inside the adjacent main tank, a fail safe design that provides continuous cooling in case the pump doesn't get shut off when the center tank goes dry.
Repositioning Boeing center tank fuel pumps into an adjacent main tank would preclude the greatest volatility of center tank explosions.
Good points Glueball:
Were the pumps in certain fuselage tanks in the KC-135 (etc) very similar to any civilian center tank pumps?
The mechanic who recently worked on our plane at a small airport had worked on some -135s at Elmendorf AFB, in Anchorage, Alaska. He told us recently that many years ago, he warned a pilot to keep the fuselage pumps off, unless a little fuel was still indicated on the gauges, to prevent overheating, and when the pilot saw that the mechanic had turned the pump (s) off, the aircraft commander quickly switched the pumps back on. The fact that the mechanic/engineer was enlisted might have been a factor. We know how certain officers will prefer to disregard an experienced enlisted man's advice...
The same pilot later died, along with the rest of his airborne crew (of course) when, as Aircraft Commander (maybe such a decision was made only to demonstrate his authority?), he operated those pump long after the tank was dry, the pumps overheated and exploded debris ignited fumes or whatever else was nearby. I can't remember if he said whether the -135's aircraft "Dash One" pilot manual had cautions or warnings about such pump(s).
This is not to suggest that anything like this happened to the TWA 747. On the contrary, are any of the other allegations, about the FBI, the unusually high level of security for the debris or the missile residue true??
Were the pumps in certain fuselage tanks in the KC-135 (etc) very similar to any civilian center tank pumps?
The mechanic who recently worked on our plane at a small airport had worked on some -135s at Elmendorf AFB, in Anchorage, Alaska. He told us recently that many years ago, he warned a pilot to keep the fuselage pumps off, unless a little fuel was still indicated on the gauges, to prevent overheating, and when the pilot saw that the mechanic had turned the pump (s) off, the aircraft commander quickly switched the pumps back on. The fact that the mechanic/engineer was enlisted might have been a factor. We know how certain officers will prefer to disregard an experienced enlisted man's advice...
The same pilot later died, along with the rest of his airborne crew (of course) when, as Aircraft Commander (maybe such a decision was made only to demonstrate his authority?), he operated those pump long after the tank was dry, the pumps overheated and exploded debris ignited fumes or whatever else was nearby. I can't remember if he said whether the -135's aircraft "Dash One" pilot manual had cautions or warnings about such pump(s).
This is not to suggest that anything like this happened to the TWA 747. On the contrary, are any of the other allegations, about the FBI, the unusually high level of security for the debris or the missile residue true??