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Delay Due To "fuel Imbalance" - Real Or An Excuse?  
User currently offlineCxsjr From , joined Dec 1969, posts, RR:
Posted (8 years 11 months ago) and read 5802 times:

Spoke with my friend who just landed at LHR on an overnight from JFK on Air India (B744).

Apparently, the flight was delayed by 1.5 hours; the pilots explanation for this was a "fuel imbalance" and they were waiting for a fuel tanker to come and remove some fuel from one tank to another.

Forgive me if I'm wrong but this sounds like bulls**t to me; surely if there's a fuel imbalance, this can be rectified by the internal pumping of fuel around the tanks?

Also, a tanker can't remove fuel from a plane, can it? I flew back from YYZ once and due to a sudden change in wind direction, we had to use a shorter runway and sat for 45 mins over the far side of the field with engines revving up to burn fuel to get down to our new MTOW for that runway (pilot said we might have to put down in Gander or Shannon to refuel but we made it in one go).

Can someone offer more info please?  airplane 

38 replies: All unread, showing first 25:
 
User currently offlineEMBQA From United States of America, joined Oct 2003, 9364 posts, RR: 11
Reply 1, posted (8 years 11 months ago) and read 5793 times:

Quoting Cxsjr (Thread starter):
Forgive me if I'm wrong but this sounds like bulls**t to me; surely if there's a fuel imbalance, this can be rectified by the internal pumping of fuel around the tanks?

It is very real and I was just reading a report on a plane that crashed near me due to fuel imbalance. This was a Beech C90, but none the less it can cause a crash and/or weight and ballance issues. As far as your friends flight.. yes, you can de-fuel using a tanker truck. Using the internal pumps to move fuel around could take much more time then moving with a truck.... but not knowing a 747-400 I can't say for sure at which would be faster. They may have also put too much on and needed to remove some.



"It's not the size of the dog in the fight, but the size of the fight in the dog"
User currently offlineCCA From Hong Kong, joined Oct 2002, 846 posts, RR: 14
Reply 2, posted (8 years 10 months 4 weeks 1 day 23 hours ago) and read 5783 times:

Quoting Cxsjr (Thread starter):
a fuel imbalance, this can be rectified by the internal pumping of fuel around the tanks?

The 747 cannot move fuel from tank to tank except during the fuel dump procedure and it can only move the fuel inboard. If you want to put fuel in the outboards, reserve or stab tank you will need a guy out under the wing at the refuel panel to connect the refuel/defuel manifolds together and then you can use the aircraft pumps to move fuel around.

Quoting Cxsjr (Thread starter):
Also, a tanker can't remove fuel from a plane, can it?

Yes you can, just the same way, hook the tanker up and use the A/C fuel pumps to pump the fuel off. Some A/C don't have a dump system so choose to fly around and burn fuel off to get to MLW, very rarely though as you should plan to arrive at you destination at a weight below MLW.



C152 G115 TB10 CAP10 SR-22 Be76 PA-34 NDN-1T C500 A330-300 A340-300 -600 B747-200F -200SF -400 -400F -400BCF -400ERF -8F
User currently offlineHAWK21M From India, joined Jan 2001, 31702 posts, RR: 56
Reply 3, posted (8 years 10 months 4 weeks 1 day 20 hours ago) and read 5729 times:

Quoting Cxsjr (Thread starter):
a tanker can't remove fuel from a plane, can it



Quoting Cxsjr (Thread starter):
if there's a fuel imbalance, this can be rectified by the internal pumping of fuel around the tanks

Was the reference to Fuel Imbalance or Excess fuel needing to be Defuelled.I Think it was the Latter.
Yes Fuel can be taken from an Aircraft to a bowser,its called Defuelling & a seperate Tanker is used.The Fuel is defuelled after certifying its condition is satisfactory & a receipt is issued by the Refuelling co to the Airline for the Fuel defuelled.

regds
MEL



Think of the brighter side!
User currently offlineCharliecossie From Germany, joined Oct 2001, 479 posts, RR: 9
Reply 4, posted (8 years 10 months 4 weeks 1 day 20 hours ago) and read 5721 times:

Quoting CCA (Reply 2):
If you want to put fuel in the outboards, reserve or stab tank you will need a guy out under the wing at the refuel panel

Not too difficult to achieve at New York.

Quoting Cxsjr (Thread starter):
Apparently, the flight was delayed by 1.5 hours; the pilots explanation for this was a "fuel imbalance" and they were waiting for a fuel tanker to come and remove some fuel from one tank to another.

Sounds like utter bollox, just another excuse for a late AI flight. JFK to LHR would have 1&4 full, reserves full, rest in 2 and 3. Due to the fuel situation at LHR, they probably tanked fuel so could have had full wings (113 tonne). Fueling is automatic. **If** there'd been an imbalance (very unlikely), would have been a simple task for the fueler to move the fuel where it should be.

Quoting Cxsjr (Thread starter):
Also, a tanker can't remove fuel from a plane, can it?

How else could the aircraft be defueled?


User currently offlineDALMD88 From United States of America, joined Jul 2000, 2614 posts, RR: 14
Reply 5, posted (8 years 10 months 4 weeks 1 day 20 hours ago) and read 5722 times:

As other have stated this is a real problem. It did sound like they had to take off fuel. Adding fuel is pretty easy. Most big airports pump from an underground manifold using a pump cart. For defueling you need a tanker truck. In ATL at some times there is only one or two for the entire airport because most of the fueling is done by the carts. At our hangar I have waited for hours for a tanker. So a 1.5 hour delay considering half of that could have been the time it took to actually transfer the excess isn't out of the norm.

User currently offlineCharliecossie From Germany, joined Oct 2001, 479 posts, RR: 9
Reply 6, posted (8 years 10 months 4 weeks 1 day 20 hours ago) and read 5709 times:

I really don't believe a 744 would need remove fuel on a JFK to LHR. Especially considering the fuel situation at LHR. Everyone's tanking fuel in.
As none of the posters seem to know the 744, I will mention that a fuel imbalance status message is no dispatch and must be corrected. However, it's no more than a 15-20 minute task to fix (no fuel truck needed).


User currently offlineHikesWithEyes From United States of America, joined Jan 2004, 816 posts, RR: 7
Reply 7, posted (8 years 10 months 4 weeks 1 day 16 hours ago) and read 5626 times:

If one of the fuel quantity gauges was on MEL, then it is possible
that a fueler overlooked the MEL and continued to fuel the aircraft.
If certain procedures aren't followed, then I can see where it would
take an hour and a half to straighten it out.
You do not want to dispatch an aircraft if you don't know exactly
how much fuel is in each tank.
AC learned that the hard way with a 767.



First, benzene in my Perrier, and now this!
User currently offlineCharliecossie From Germany, joined Oct 2001, 479 posts, RR: 9
Reply 8, posted (8 years 10 months 4 weeks 1 day 15 hours ago) and read 5604 times:

Takes 10 minutes to dip a tank on a 747.

User currently offlineBohica From United States of America, joined Feb 2004, 2748 posts, RR: 0
Reply 9, posted (8 years 10 months 4 weeks 1 day 11 hours ago) and read 5526 times:

Quoting DALMD88 (Reply 5):
For defueling you need a tanker truck.



Quoting DALMD88 (Reply 5):
some times there is only one or two for the entire airport because most of the fueling is done by the carts.

And if both tankers are topped off, you're screwed. You then have to wait for the tanker to fuel a plane or two before it can defuel yours.


User currently offlineCancidas From Poland, joined Jul 2003, 4112 posts, RR: 11
Reply 10, posted (8 years 10 months 4 weeks 1 day 11 hours ago) and read 5512 times:

removing fuel from airplanes is a pesky deal though. depending on how much was pumped in, certain companies will not allow any more than they pumped in to be removed. other times, defueling never happens for fear of contaminating supplies. on wx days at work there are loads of weight and balance issues, many pertaining to increased fuel loads. there have been situations in the past where wx has cleared and the crews want to defuel the airplane in order to take more pax. there was one that came in as a ferry from BOS and had so much fuel onboard that the outbound actually cancelled since it wouldn't make sense to take the 8 or so pax that he would have been able to.


i know when i learned fuel quality control you never pumped gas out of a plane that wasn't yours. even more so you never put it back in your farm. if you had to take fuel out you would first find an empty tanker to drain into, let it sit overnight for any particles to settle and then sump it in the morning. if it turned out being a good fuel then you were allowed to pump it, but it was never allwoed to leave that truck.



"...cannot the kingdom of salvation take me home."
User currently offlineHAWK21M From India, joined Jan 2001, 31702 posts, RR: 56
Reply 11, posted (8 years 10 months 4 weeks 1 day 5 hours ago) and read 5424 times:

Quoting Charliecossie (Reply 8):
Takes 10 minutes to dip a tank on a 747.

From the time the Defuelling bowser is hooked up.

Quoting Bohica (Reply 9):

 bigthumbsup 
Depends on how long the Bowser took to arrive.Difficult to tell without knowing the details.
regds
MEL



Think of the brighter side!
User currently offlineWhiskeyflyer From Ireland, joined May 2002, 224 posts, RR: 0
Reply 12, posted (8 years 10 months 4 weeks 1 day 2 hours ago) and read 5401 times:

I congradulate the captain for being honest and saying fuel imbalance and not some "technical delay". Better that then reading aircraft crashes due to fuel imbalalce.
Delay may have been 1.5 hours but what seems easy to do sitting on your chair can be a complete pain at a major airport. Due to cost cutting, forcing more aircraft into airport, contract workers, industrial action by any of a multitude of suppliers etc, when you want something out of the ordinary done it can take an unusual amount of time. Fuel bowsers are expensive and are scheduled to be at aircraft certain times and if you want one back, you wait in the queue, and the tanker does not do 120Km/Hr rushing to your aircraft.
Also we do not know the technical condition of aircraft at the time, where all functions on the fuel panel working, was there a mitigating open MEL item, what is company SOP for this problem etc etc etc?
One of our aircraft had a bust fuel panel once, lead time 4 days, so all our fueling was dip stick reading for a week (the replacement panel also got stuck in customs) Another time we needed to drain fuel (for an aircraft weigh) and our airport only uses a special seperate old truck for defueled fuel and guess what? it had not been used for a while and the battery was flat.
Aviation industry is only organised chaos


User currently offlineCharliecossie From Germany, joined Oct 2001, 479 posts, RR: 9
Reply 13, posted (8 years 10 months 4 weeks 23 hours ago) and read 5378 times:

Mr Hawk:
One does not need a fuel bowser to dip a tank.

Mr Whiskyflower:
Believe me,I am intimately aware of 747 tanks/fuel procedures/etc. I can imagine no "fuel imbalance" (there *must* have been a status message) that would require a wait for a fuel truck and a 1.5 hr delay.

12 replies to this post. How many of you are 744 experienced?


User currently offlineHAWK21M From India, joined Jan 2001, 31702 posts, RR: 56
Reply 14, posted (8 years 10 months 4 weeks 19 hours ago) and read 5330 times:

Quoting Charliecossie (Reply 13):
One does not need a fuel bowser to dip a tank.

Pls elaborate.
regds
MEL



Think of the brighter side!
User currently offlinePlanefreakaa From United States of America, joined Jan 2005, 111 posts, RR: 0
Reply 15, posted (8 years 10 months 4 weeks 19 hours ago) and read 5325 times:

OK here is the deal, you have fueling valves and defueling valves on the aircraft. The fueling valves have a check valve on them which means that the fuel can only go one direction
it is possible that they had a fuel imbalance being that the APU runs off of one of the wing tanks. I'm sure the APU on the 747 burns up to 500 pounds per hour, and if left unchecked could really imbalance the fuel load
the way it works is to transfer fuel or to defuel it is all done from the fueling station on the wing.
To transfer fuel you have to open the fueling valve on the wing you want the fuel to go into, and open the defueling valve on the wing you want to take fuel out of, when this is set you have to go to the cockpit and then turn on the fuel boost pumps for the wing you want to take fuel out of.
Just this set up of getting up to the fuel station going back down and then up to the cockpit can take fifteen minutes


User currently offlinePlanefreakaa From United States of America, joined Jan 2005, 111 posts, RR: 0
Reply 16, posted (8 years 10 months 4 weeks 19 hours ago) and read 5323 times:

by the way just to let everyone know this is how the 777, 767, 757, 737, and MD-80's work. I'm just assuming the 747 is the same way.

User currently offlineMatt72033 From United Kingdom, joined May 2005, 1617 posts, RR: 4
Reply 17, posted (8 years 10 months 4 weeks 19 hours ago) and read 5322 times:

Quoting Planefreakaa (Reply 15):
APU runs off of one of the wing tanks. I'm sure the APU on the 747 burns up to 500 pounds per hour

runs off tank 2 or 3, normally 2, but surely if there it was going to create an imbalance situatiopn it would swap to feed from tank 3?


User currently offlinePlanefreakaa From United States of America, joined Jan 2005, 111 posts, RR: 0
Reply 18, posted (8 years 10 months 4 weeks 19 hours ago) and read 5321 times:

Quoting Matt72033 (Reply 17):
but surely if there it was going to create an imbalance situatiopn it would swap to feed from tank 3?

is this a automatic system that would switch from 2 to 3 or does someone have to throw a switch?


User currently offlineHAWK21M From India, joined Jan 2001, 31702 posts, RR: 56
Reply 19, posted (8 years 10 months 4 weeks 19 hours ago) and read 5315 times:

Quoting Planefreakaa (Reply 15):
Just this set up of getting up to the fuel station going back down and then up to the cockpit can take fifteen minutes

Isn't the Service Interphones used on the B744.
regds
MEL



Think of the brighter side!
User currently offlineA/c train From United Kingdom, joined Jun 2001, 501 posts, RR: 4
Reply 20, posted (8 years 10 months 4 weeks 18 hours ago) and read 5311 times:

This, again is a had too be there situation, I cant see that with automatic fuelling control, you would have an imbalance, its quite simple, you pre-select then set then open valve and pump. Fill wing first and rest in centre. APU running has never been a problem before from my experience although have never worked on 747. A fuel imbalance EICAS status message is a probability however, this would mean going to the MEL and looking for the status message and if no dispatch, look for maintenance action and/or follow the Fault isolation manual which will have the status message in it, then the corrective action/trouble shooting action suggested. It is quite likely that using the magnetic fuel level indicators is suggested in the troubleshooting.
regds a/c


User currently offlineMatt72033 From United Kingdom, joined May 2005, 1617 posts, RR: 4
Reply 21, posted (8 years 10 months 4 weeks 17 hours ago) and read 5294 times:

Quoting HAWK21M (Reply 19):
Isn't the Service Interphones used on the B744.

we never use the service interphones! we just use our hand held radios!
i seem to remember using it once, but this was as i was a newbie on the pushbacks and we couldnt find the headset splitter, i used the service interphone, whilst the other guy used the flight interphone! i had to bail out once we got all 4 engines started, i couldnt hear a word the pilots were saying, so much interference!


User currently offlineZeke From Hong Kong, joined Dec 2006, 9229 posts, RR: 76
Reply 22, posted (8 years 10 months 4 weeks 15 hours ago) and read 5266 times:

Any reason the captain raises that a flight should be delayed is okay.

The the only legal person who has the say at the end of the day to go or not is the captain.

Stupid to second guess a captains decision, espically when all the facts are not know to a.net.

Fact : Fuel imbalance is a limitation on the 744, out of balance no go.



We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
User currently offlineMatt72033 From United Kingdom, joined May 2005, 1617 posts, RR: 4
Reply 23, posted (8 years 10 months 4 weeks 15 hours ago) and read 5258 times:

Quoting Zeke (Reply 22):
The the only legal person who has the say at the end of the day to go or not is the captain

not true really......if engineers wont sign....the plane aint going anywhere
if engineer signs for it, captain can say no, airline can find another captain willing to take the aircraft!


User currently offlineCharliecossie From Germany, joined Oct 2001, 479 posts, RR: 9
Reply 24, posted (8 years 10 months 4 weeks 15 hours ago) and read 5255 times:

Quoting Zeke (Reply 22):
Fact : Fuel imbalance is a limitation on the 744, out of balance no go.

Zeke:
Yes, it's a no go. My point, from the beginning, was that it doesn't take 90 minutes to fix it. Neither does it need a fuel truck.

Quoting HAWK21M (Reply 14):
One does not need a fuel bowser to dip a tank.

Pls elaborate.

Mr Hawk:
Perhaps it's you who should elaborate and tell us all why one might need a fuel truck to check an MLI on a 744.

Quoting Zeke (Reply 22):
Any reason the captain raises that a flight should be delayed is okay.

*Any* reason? You're joking. No way!

Quoting Zeke (Reply 22):
The the only legal person who has the say at the end of the day to go or not is the captain.

Stupid to second guess a captains decision, espically when all the facts are not know to a.net.

Not quite true. The person releasing the aircraft for service also needs to be satisfied. No release, no service.
In this case, the OP stated that the 90 minute delay was due to waiting for a fuel truck to correct a "fuel imbalance". I have stated that this doesn't need a fuel truck nor 90 minutes to fix and I stand by it.


25 A319XFW : Unless it's a ball-valve and then fuel can go either way. Which even if it's used that in an hour is a tiny fuel mass (and then imbalance) for an air
26 Jetlagged : Not that I'm disagreeing with you, however you say it can be done, but have not said how. I recall the 747 Classic had a limited means to transfer fu
27 Charliecossie : 744 fuel transfer: Turn on pumps for tank to be defueled. Go to refuel panel. Open defuel valve (a lever). Open refuel valve of receiving tank (a swit
28 SkydrolBoy : 15 mins max, must have some super duper pumps the size of a car installed in the wing then, cause I transfer fuel from tank to tank on 27's, 37's, an
29 DCrawley : Didn't this happen with the Iranian Air Force C-130 crash in Tehran? I'm looking for an internet article confirmation, but haven't found one yet.
30 Charliecossie : The amount to transfer would be less than a tonne. Anyway, still doesn't need a fuel truck. Not really, boarding would start after refuel complete no
31 HAWK21M : Since you are B744 experienced.Maybe its the language.What do you mean by dip.Are you talking of level of Fuel in tank checking.I was stating that is
32 Charliecossie : "Dip" is an even older term than "drip".
33 HAWK21M : What did you mean by Dip in reference to your post. regds MEL
34 SkydrolBoy : So how do you know that in the flight that started this topic that only a tonne needed to be moved. You should really be more considerate of others p
35 Charliecossie : In which case, the Air India captain lied about the reason for the delay as it would not have been for a fuel imbalance. Which is my whole point. Wha
36 Nonfirm : This is a common problem.You could get a fuel imbalance during fuel stick procedures also if you have an a/c with dispatch fuel for one place and the
37 HAWK21M : I feel its a Defuelling reason & not Imbalance.Could be the pilot meant Imbalance in terms of excess fuel could lead to.... Ideal if someone could pas
38 KBGRbillT : You don't honestly think that with all of the 744's out there, you're the only one that has fueled a 744 or knows anything about it, do you? Come on!
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