B-737 fuel tanks...

[DeltaTango]

The Federal Aviation Administration ordered airlines to shut
off fuel pumps on Boeing 737s when there is a low level of fuel remaining in the
center tank. Fuel tanks have been blamed for an explosion last month aboard a
Thai Airways Boeing 737 and for the 1996 destruction of TWA Flight 800.

Can anybody explain this?

Cheers
DT

[Iz]

Hmm, just a guess, maybe it's due to ignition of the left-over fumes in an empty tank? I thought that on some of the older aircraft, insulation of the electric wires running through there was almost gone. But I could be wrong though.

[static]

This note only covers PROLONGED running of the center fuel tanks, with an empty center tank. That MIGHT cause the fuel pumps to run hot, which MIGHT cause fuel vapours to ignite. Since there is absolutely no use for the fuel pumps to run with an empty center fuel tank, this is nothing extraordinary.

[DeltaTango]

Cheers.....

DT

[OLD_EGG_BOUND]

try this web page for news reports concerning centre fuel tank explosions.

http://www.b737.org.uk/thai737news.htm

[lame]

The FAA issued AD says that you must NOT have the centre tank pumps on unless you have 1000 LBS (453 KGS) minimum in the centre tank, except for defuelling or transferring. Also any time they are on, you must have someone in the cockpit monitoring them, and you must turn them off as soon as the low pressure lights come on.



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"I USED to be a PPRuNaholic, but now I'm CURED"

[Slasher]

Yeh lame we got that AD too. But can you answer this question please mate? Knowing that the CT pumps themselves are actualy located in the main tanks, shouldnt the 453kg limit (and whyd they pick 453kg? Thats a main tank imbalace limit!) apply to the main tank level instead, when operating the centre pump(s)? Thanks.

[Denti]

I don't know about your SOPs but according to ours we are not allowed to use fuel from the maintanks if we have more than 453kgs in the centertank. I didn't know that the CT-pumps are in the maintanks, i always thought that only the scavenge-pump is located in the left maintank.

Denti

[BOAC]

Denti is correct. The centre tank pumps are in the centre tank. The scavenge pump is in the left main.

[lame]

Slasher,

Sorry, I don't visit this forum very often, just saw your post, but looks like you have the answer now?

Centre pumps are in centre tank using centre fuel, #1 and #2 main pumps are in #1 and #2 main wing tanks using main tank fuel. Scavenge jet pump is located in #1 main tank but uses centre tank fuel, when operating, which can be for up to 20 minutes from memory after turning off centre pumps, to scavenge centre tank. Some aircraft also have a DC boost pump in #1 tank using its fuel.

I do not know about the 453KGS, except that it is the conversion of 1000LBS figure issued by Boeing and the FAA, you would have to ask them?

Best regards,

"lame"

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"I USED to be a PPRuNaholic, but now I'm CURED"

[This message has been edited by lame (edited 08 May 2001).]

[WideBodiedEng]

Hello...... hello........
(Deafening Silence)
Where are the people who want the 146 grounded now??

Hello....... hello.............

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The Stamp is mightier than the Toolbox!!

[DeltaTango]

widebodiedeng-NO.

This is the foundation to save the rj

[Slasher]

Nah Im pretty sure that that part of the pump doing all the work is in the main tanks, with a spline running through to the CT to the pump-part thats actualy shoving the fuel through (whatever the hell its called again)

Anyway one of our 73s is due to be pulled to bits in the hangar next week by all the kings men so Ill stick my head up there and have a look.

[Canuck_AV8R]

I checked with our resident Boeing rep and he confirmed that the centre tank pumps on the B737-200 are located in an "igloo" in the respective main tank. The reason for the AD is the fear of propogation of fumes in the centre tank due to prolonged running of the centre tank pumps on the ground in high temperature conditions with little or no lubrication.

I do not know why anyone would want the centre tank pumps on for a prolonged period on the ground anyway but that is just my opinion and you know what they say about opinions, they are like assholes, everyone has one :-))

Cheers

[TR4A]

The pumps on the -300 and later models are BRITISH made pumps and you should turn them off when the low pressure light comes on. Something to do with cooling. Why didn't Boeing use American pumps?

[critcaact]

Hands across the water and all that what?