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Fuel Tank Explosions  
User currently offlineUTwriter From United States of America, joined May 2006, 16 posts, RR: 0
Posted (8 years 2 months 1 week 4 days 11 hours ago) and read 2407 times:

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

9 replies: All unread, jump to last
 
User currently offlineStarlionblue From Greenland, joined Feb 2004, 17043 posts, RR: 66
Reply 1, posted (8 years 2 months 1 week 4 days 10 hours ago) and read 2397 times:

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."
User currently offlineSeanp11 From United States of America, joined Jan 2006, 290 posts, RR: 0
Reply 2, posted (8 years 2 months 1 week 4 days 10 hours ago) and read 2386 times:

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.


User currently offlineUtwriter From United States of America, joined May 2006, 16 posts, RR: 0
Reply 3, posted (8 years 2 months 1 week 3 days 21 hours ago) and read 2306 times:

"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!!!


User currently offlineMarkHKG From United States of America, joined Dec 2005, 960 posts, RR: 2
Reply 4, posted (8 years 2 months 1 week 3 days 19 hours ago) and read 2288 times:

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!
User currently offlineHAWK21M From India, joined Jan 2001, 31684 posts, RR: 56
Reply 5, posted (8 years 2 months 1 week 3 days 17 hours ago) and read 2271 times:

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



Think of the brighter side!
User currently offlineStarlionblue From Greenland, joined Feb 2004, 17043 posts, RR: 66
Reply 6, posted (8 years 2 months 1 week 3 days 13 hours ago) and read 2243 times:

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."
User currently offlineGreasespot From Canada, joined Apr 2004, 3084 posts, RR: 20
Reply 7, posted (8 years 2 months 1 week 3 days 6 hours ago) and read 2196 times:

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?"
User currently offlineStarlionblue From Greenland, joined Feb 2004, 17043 posts, RR: 66
Reply 8, posted (8 years 2 months 1 week 3 days 6 hours ago) and read 2194 times:

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."
User currently offlineTWAL1011727 From United States of America, joined Mar 2006, 629 posts, RR: 0
Reply 9, posted (8 years 2 months 1 week 3 days 5 hours ago) and read 2187 times:

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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