UTwriter
Topic Author
Posts: 16
Joined: Tue May 09, 2006 10:55 am

Fuel Tank Explosions

Sat Jul 15, 2006 12:05 am

Hi all, hoping some of you could explain this article further pertaining to the cause of twa 800 being a fueltank expolsion as a resut of vaporized fuel in the center tank. Any of you have a take on the article? Thanks!
http://www.cnn.com/2006/US/07/14/twa.main/index.html
 
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Starlionblue
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Joined: Fri Feb 27, 2004 9:54 pm

RE: Fuel Tank Explosions

Sat Jul 15, 2006 12:43 am

Note: I will ignore any conspiracy theories and alternate explanations.

Note: This is my understanding as a layman. I might be getting the details wrong.


- The center tank was not full due to the Paris leg not requiring it. There was thus air in the tank (above the fuel). Since we're talking a closed environment, fuel fumes were present. As you probably know, you can drop a match in for example gas and it will go out. It's the fumes that can explode at certain concentrations fuel/air. That's why fuel is turned to mist or to combustion.
- Overflow vents were open to the air. With increasing altitude, this allowed air to escape and thus lowered the air pressure in the tank to a level allowing combustion of the fumes.
- Wire bundles going through the tank had rubbed through the wire sheahts (the plastic tubes that cover the wires) over years of use, exposing naked wire inside the tank.
- There was a spark. Boom!

It took a while to figure out why the fuel ignited. They had to use a vacuum chamber to lower the pressure before they could replicate the conditions.w

Among the evidence, it was found that the forward bulkhead of the center tank had buckled and been thrown forward.


The article speaks of measures being taken to pump nitrogen into the tanks as they empty. This would render the non-fuel volume in the tanks inert and prevent combustion.

IIRC an immediate measure soon after the accident was to require inspection of wiring and replacement of sheaths with kevlar ones less prone to shedding.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
seanp11
Posts: 281
Joined: Tue Jan 10, 2006 6:16 am

RE: Fuel Tank Explosions

Sat Jul 15, 2006 1:03 am

http://www.b737.org.uk/fuel.htm#Centre_Fuel_Tank_Inerting
The B737 is the only other airliner to have experienced central fuel tank explosions, and future production 737s will have the equipment to inert the central fuel tank.

Mind you, the TWA800 explosion occurred due to an errant spark, not just because the fuel tank was not inerted. When they fixed the wiring after the crash, they eliminated the source of the spark. People aren't at the same risk as CNN would lead people to believe.
 
UTwriter
Topic Author
Posts: 16
Joined: Tue May 09, 2006 10:55 am

RE: Fuel Tank Explosions

Sat Jul 15, 2006 2:08 pm

"People aren't at the same risk as CNN would lead people to believe."

I hope everyone if as rational...I felt that this really was more of a fear tactic on CNN's part, rather than a chance to educate people...well, I know, big suprise there!!!
 
Markhkg
Posts: 838
Joined: Mon Dec 05, 2005 4:13 pm

RE: Fuel Tank Explosions

Sat Jul 15, 2006 3:35 pm

This article from Flight Global recently posted may also interest you:

http://www.flightglobal.com/Articles...led+to+stop+Malaysian+carrier.html

By Darren Shannon in Washington DC

An investigation of the 4 May explosion of a Transmile Airlines Boeing 727-200 freighter’s left wing during towing at Bangalore airport has found evidence of damaged wiring and electrical arcing within the wing’s fuel tank.

...

“Had this explosion occurred in flight, it would have resulted in the catastrophic failure of the wing and the airplane would have crashed,” it adds.

...

“This accident illustrates that ignition sources continue to exist and fuel tank explosions continue to occur in both wing and center wing fuel tanks despite the corrective efforts of government regulators and industry,” says the NTSB.

It adds: “The safety board continues to believe the best protection against fuel tank explosions is to eliminate the flammable conditions inside the fuel tanks through design changes such as nitrogen-inerting systems.”
Release your seat-belts and get out! Leave everything!
 
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HAWK21M
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RE: Fuel Tank Explosions

Sat Jul 15, 2006 6:00 pm

Quoting Seanp11 (Reply 2):
and future production 737s will have the equipment to inert the central fuel tank.

Whats the Method considered.Is it Inert Gas.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
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Starlionblue
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Joined: Fri Feb 27, 2004 9:54 pm

RE: Fuel Tank Explosions

Sat Jul 15, 2006 9:43 pm

Quoting HAWK21M (Reply 5):
Quoting Seanp11 (Reply 2):
and future production 737s will have the equipment to inert the central fuel tank.

Whats the Method considered.Is it Inert Gas.

Nitrogen. It's mentioned in the article.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
greasespot
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Joined: Sat Apr 24, 2004 10:48 am

RE: Fuel Tank Explosions

Sun Jul 16, 2006 5:11 am

Also the airconditiong packs are under the center fuel tank. and on TWA the center tank was nearly empty..There is a theory that with the residual fuel the packs heated the fuel...As the pressure dropped the boiling point was lowererd and the fuel turned to vapour more easily

There was a PAL B737 the exploeded at the gate due to the center fuel tank.
There have been a number of AD's concerening the wiring. in '98 there was a immediat grounding AD. We had to replace the wiring harness going into the wing tanks.

GS
Sometimes all you can do is look them in the eye and ask " how much did your mom drink when she was pregnant with you?"
 
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Starlionblue
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Joined: Fri Feb 27, 2004 9:54 pm

RE: Fuel Tank Explosions

Sun Jul 16, 2006 5:14 am

Quoting Greasespot (Reply 7):
Also the airconditiong packs are under the center fuel tank. and on TWA the center tank was nearly empty..There is a theory that with the residual fuel the packs heated the fuel...As the pressure dropped the boiling point was lowererd and the fuel turned to vapour more easily

Indeed. They are under the front part. This is not an accident. They heat the fuel. As you say heat was contributory.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
twal1011727
Posts: 449
Joined: Thu Mar 23, 2006 5:36 am

RE: Fuel Tank Explosions

Sun Jul 16, 2006 5:27 am

Quoting Utwriter (Reply 3):
I hope everyone if as rational...I felt that this really was more of a fear tactic on CNN's part, rather than a chance to educate people...well, I know, big suprise there!!!

All the news media does is frighten the piss outta people...Thats their lot in life.

Its all the ratings game....CNN says it first, in a spectacular way and they'll get the viewers - or NBC/CBS/ABC etc...

The viewers also have a twisted sense of what they want to be told - rational or sensational - then they make their decision to watch on or change channels

KD MLB

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