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AD 2002-19-52 Do you guys know about that? center fuel tank

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Just in case someone did not read carefully FCOM (as myself until couple a days ago)." The center tank fuel pumps must be OFF for takeoff if center tank fuel is less than 5,000 pounds(2,300 kilograms) with the airplane readied for initial taxi.Both center tank fuel pump switches must be selected OFF when center tank fuel quantityreaches approximately 1,000 pounds (500 kilograms) during climb and cruise or 3,000 pounds (1,400kilograms) during descent and landing. The fuel pumps must be positioned OFF at the first indicationof fuel pump low pressure.The CWT fuel quantity indication system must be operative to dispatch with CWT mission fuel.7NoteThe CONFIG indicator will annunciate when center tank fuel exceeds 1,600 pounds (800kilograms) and the center tank fuel pump switches are OFF. Do not accomplish the CONFIG nonnormalprocedure prior to or during takeoff with less than 5,000 pounds (2,300 kilograms) of centertank fuel or during descent and landing with less than 3,000 pounds (1,400 kilograms) of center tankfuel.NoteIn a low fuel situation, both center tank pumps may be selected ON and all center tank fuel maybe used.If the main tanks are not full, the zero fuel gross weight of the airplane plus the weight of centertank fuel may exceed the maximum zero fuel gross weight by up to 5,000 pounds (2,300 kilograms)for takeoff, climb and cruise and up to 3,000 pounds (1,400 kilograms) for descent and landing,provided that the effects of balance (CG) have been considered.If a center tank fuel pump fails with fuel in the center tank, accomplish the FUEL PUMP LOWPRESSURE non-normal procedure.When defueling center or main wing tanks, the Fuel Pump Low Pressure indication lights mustbe monitored and the fuel pumps positioned to OFF at the first indication of fuel pump low pressure.Defueling with passengers on board is prohibited.The limitations contained in this AD supersede any conflicting basic airplane flight manuallimitations. ''


Alexandre Blumberg

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AFAIK this only applies to aircraft equipped with the old pumps (these are normally placarded). With the new ones (and this is from a specific airline´s FCOM) the center tank pumps must only be switched off prior to departure provided there is less than 500 kgs in it and the pumps can be turned back on after passing 10.000 ft (a/c body angle decreases). Also, with the new pumps the ctr tank can be fully emptied and doesn´t need to be switched off with a given amount left in it.Maybe Andrea can elaborate further on this topic.Robert

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We discussed this topic a bit in this thread:http://forum.avsim.net/topic/345402-center-tank-ran-out-fuel-with-fuel-switches-off/page__p__2091999__hl__amoc__fromsearch__1#entry2091999


Matt Cee

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Just in case someone did not read carefully FCOM (as myself until couple a days ago)." The center tank fuel pumps must be OFF for takeoff if center tank fuel is less than 5,000 pounds(2,300 kilograms) with the airplane readied for initial taxi.Both center tank fuel pump switches must be selected OFF when center tank fuel quantityreaches approximately 1,000 pounds (500 kilograms) during climb and cruise or 3,000 pounds (1,400kilograms) during descent and landing. The fuel pumps must be positioned OFF at the first indicationof fuel pump low pressure.The CWT fuel quantity indication system must be operative to dispatch with CWT mission fuel.7NoteThe CONFIG indicator will annunciate when center tank fuel exceeds 1,600 pounds (800kilograms) and the center tank fuel pump switches are OFF. Do not accomplish the CONFIG nonnormalprocedure prior to or during takeoff with less than 5,000 pounds (2,300 kilograms) of centertank fuel or during descent and landing with less than 3,000 pounds (1,400 kilograms) of center tankfuel.NoteIn a low fuel situation, both center tank pumps may be selected ON and all center tank fuel maybe used.If the main tanks are not full, the zero fuel gross weight of the airplane plus the weight of centertank fuel may exceed the maximum zero fuel gross weight by up to 5,000 pounds (2,300 kilograms)for takeoff, climb and cruise and up to 3,000 pounds (1,400 kilograms) for descent and landing,provided that the effects of balance (CG) have been considered.If a center tank fuel pump fails with fuel in the center tank, accomplish the FUEL PUMP LOWPRESSURE non-normal procedure.When defueling center or main wing tanks, the Fuel Pump Low Pressure indication lights mustbe monitored and the fuel pumps positioned to OFF at the first indication of fuel pump low pressure.Defueling with passengers on board is prohibited.The limitations contained in this AD supersede any conflicting basic airplane flight manuallimitations. ''
I feel you may be correct but NGX warns you just when the central tank is empty and the warning comes off when you switch the central tanks pumps off.Maybe in the reality is different and if the guy in the avatar is you, well, of course you are correct :(

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I feel you may be correct but NGX warns you just when the central tank is empty and the warning comes off when you switch the central tanks pumps off.Maybe in the reality is different and if the guy in the avatar is you, well, of course you are correct smile.png
The 737 warns you when there's low pressure for that particular pump, not when the fuel is below 5,000lbs like when the Airworthiness Directive dictates pumps should be off for takeoff... The low pressure lights come on because if the fuel pump continues to pump with no fuel in the line (low pressure light illuminated) the pump will lose it's priming, and can't be primed even after refueling. That is to say it will be inoperative until required maintenance is performed.Notice in his avatar he's wearing normal clothes. Getting a cockpit tour doesn't make you an expert! LOL.gif All the same, he's absolutely correct about the AD.
AFAIK this only applies to aircraft equipped with the old pumps (these are normally placarded). With the new ones (and this is from a specific airline´s FCOM) the center tank pumps must only be switched off prior to departure provided there is less than 500 kgs in it and the pumps can be turned back on after passing 10.000 ft (a/c body angle decreases). Also, with the new pumps the ctr tank can be fully emptied and doesn´t need to be switched off with a given amount left in it.Maybe Andrea can elaborate further on this topic.Robert
That's my understanding. Hydro-Aire pumps only.

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The 737 warns you when there's low pressure for that particular pump, not when the fuel is below 5,000lbs like when the Airworthiness Directive dictates pumps should be off for takeoff..
I think I've stated the same telling " empty ".But I dunno if the "" 5000 rules " is correct for triggering the warning or it is correct like NGX therefore when the central tank is " empty " or at 0 .Regarding the clothes, he is clearly a real pilot dressed on civilian clothes :(

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The 737 warns you when there's low pressure for that particular pump, not when the fuel is below 5,000lbs like when the Airworthiness Directive dictates pumps should be off for takeoff... The low pressure lights come on because if the fuel pump continues to pump with no fuel in the line (low pressure light illuminated) the pump will lose it's priming, and can't be primed even after refueling. That is to say it will be inoperative until required maintenance is performed.That's my understanding. Hydro-Aire pumps only.
I don't think there's a priming issue with the pumps and I've never had to call MX out for a fuel pump issue. At my current airline, we run the pumps dry all of the time. Master Caution - Fuel - Low Press - Pump Off - Get more coffee.The only real trick is on some planes, you turn off one pump and open the x-feed so you get a master caution when that pump runs dry.

Matt Cee

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If I would be in the air with a pump issue beside calling MX I would also try to land at the closest airport declaring an emergency or a pan pan pan at least.I like to be on the safe side, but I can understand companies would think the opposite.What do you think Spin ?Much appreciated

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If I would be in the air with a pump issue beside calling MX I would also try to land at the closest airport declaring an emergency or a pan pan pan at least.I like to be on the safe side, but I can understand companies would think the opposite.What do you think Spin ?Much appreciated
Hmmm. What's your scenario, Mark? Center Tank Low Press lights come on all the time, and it's not an emergency, it's a reminder.The big problem would be if somehow you lost both Center Tank pumps with a lot of fuel in the Center Tank. If you were half way to Hawaii and you suddenly couldn't use 10,000 pounds of fuel in the Center Tank. Then you might have some problems.

Matt Cee

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Hmmm. What's your scenario, Mark? Center Tank Low Press lights come on all the time, and it's not an emergency, it's a reminder.The big problem would be if somehow you lost both Center Tank pumps with a lot of fuel in the Center Tank. If you were half way to Hawaii and you suddenly couldn't use 10,000 pounds of fuel in the Center Tank. Then you might have some problems.
Yeah you are right it depends on the precise situation.It must be really difficult anyway dealing in the air with a problem and meanwhile deciding if trying a checklist to fix it or decide to divert to a close airport despite the fix somehow worked.Have you ever found yourself in a similar situation where you had to take such a decision ?

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I don't think there's a priming issue with the pumps and I've never had to call MX out for a fuel pump issue. At my current airline, we run the pumps dry all of the time. Master Caution - Fuel - Low Press - Pump Off - Get more coffee.The only real trick is on some planes, you turn off one pump and open the x-feed so you get a master caution when that pump runs dry.
Hopefully you're aware that running them for an extended time with no fuel in the line (ten minutes according to Boeing) will "un-prime" them.

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Zachary Waddell -- Caravan Driver --

Facebook: http://www.facebook.com/zwaddell

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Notice in his avatar he's wearing normal clothes. Getting a cockpit tour doesn't make you an expert! LOL.gif All the same, he's absolutely correct about the AD. That's my understanding. Hydro-Aire pumps only.
I think I've stated the same telling " empty ".But I dunno if the "" 5000 rules " is correct for triggering the warning or it is correct like NGX therefore when the central tank is " empty " or at 0 .Regarding the clothes, he is clearly a real pilot dressed on civilian clothes tongue.png
The post was to hear from real 737 pilots, what they do in real operations?In my last flight I leave 500kg on Center tank, and when on the ground I realize that there was 0 kg and an imbalance between T1 and T2! Great job PMDG indeed.Regarding my avatar is me in a B757F I was powerplant engineer at Variglog, but seriously considering to get my CPL in USA next year, so if you know about a good school there, send private message please Whistle.gif

Alexandre Blumberg

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Hopefully you're aware that running them for an extended time with no fuel in the line (ten minutes according to Boeing) will "un-prime" them.
Unless both pilots have gone blind and can't see the Master Caution that comes on, then you won't get to ten minutes. The guidance is to turn the pumps off immediately when you get the light. The planes with the auto-shutoff do it in 10 seconds, that should give you about 9minutes and 50 seconds to spare. If the pilots have gone blind, then you've got bigger problems than un-primed pumps.
Yeah you are right it depends on the precise situation.It must be really difficult anyway dealing in the air with a problem and meanwhile deciding if trying a checklist to fix it or decide to divert to a close airport despite the fix somehow worked.Have you ever found yourself in a similar situation where you had to take such a decision ?
Luckily I haven't had any situations where I've been dealing with a fuel issue and a mechanical. Not that I recall, anyway. Plenty of diversions and mechanicals, though.This is the area where it's obvious why airliners have two pilots. On my last sim check, we had a cargo fire. Captain said, let's go back to our origin. I took care of ATC and Flying and Navigating, and the Captain handled the emergency. By the time he was done with his work, I had us approaching the marker. Teamwork.

Matt Cee

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The post was to hear from real 737 pilots, what they do in real operations?In my last flight I leave 500kg on Center tank, and when on the ground I realize that there was 0 kg and an imbalance between T1 and T2! Great job PMDG indeed.Regarding my avatar is me in a B757F I was powerplant engineer at Variglog, but seriously considering to get my CPL in USA next year, so if you know about a good school there, send private message please Whistle.gif
I have direct access to an active 737 captain. I actually had this conversation with him years ago, and SOPs for his airline does follow this AD, or rather the AD applies to their aircraft.
Unless both pilots have gone blind and can't see the Master Caution that comes on, then you won't get to ten minutes. The guidance is to turn the pumps off immediately when you get the light. The planes with the auto-shutoff do it in 10 seconds, that should give you about 9minutes and 50 seconds to spare. If the pilots have gone blind, then you've got bigger problems than un-primed pumps.
I don't think there's a priming issue with the pumps and I've never had to call MX out for a fuel pump issue. At my current airline, we run the pumps dry all of the time. Master Caution - Fuel - Low Press - Pump Off - Get more coffee.
I just thought it was odd you had no clue what I was talking about with the priming issue until after I mentioned the "10 minute" rule.

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Zachary Waddell -- Caravan Driver --

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I just thought it was odd you had no clue what I was talking about with the priming issue until after I mentioned the "10 minute" rule.
Yep, I thought the bigger issue was pumps overheating and kablammo! But, I hadn't heard the 10 minute note before. I'll let you in on a little secret - airline pilots don't know everything about their planes. The company has engineers for that. They tell us what not to do and we don't do it. If you happen to find out the why, that's great. Something that you and I like to learn.You'll note that neither the AD nor the FCOM nor the AFM mention anything about a 10 minute guideline. AD 2002-19-52 is concerned with sparks and fire. I'd be willing to bet most 737 drivers have no idea about a 10 minute guide. You tell me which is the greater concern. ;)

Matt Cee

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