Trent800
Topic Author
Posts: 8
Joined: Wed Sep 19, 2001 7:47 pm

Air-to-Air Refuelling Fuel Spillage

Thu May 30, 2002 6:40 pm

Everytime I see an aircraft being refuelling in the air by use of the boom and receptacle system as used by the USAF is seen fuel being spilled when the boom is decoupled after refuelling (e.g. A-10 or F-16).
I would like to know whether this is "standard-practice" or whether this can be controlled by the boom operator, so that no fuel is spilled and wasted when the boom is disconnected.
 
broke
Posts: 1299
Joined: Wed Apr 24, 2002 8:04 pm

RE: Air-to-Air Refuelling Fuel Spillage

Thu May 30, 2002 9:49 pm

From what I've seen, this spillage is typical and really not much is lost. The problem is, if the refueling port is forward of the cockpit (a la A-10), then you get you windshield covered in fuel. I'm not sure if it would obstruct vision when it dries, but I would think so. I believe that is why the refueling port for the the flying boom system is almost always behind the cockpit.
 
Trent800
Topic Author
Posts: 8
Joined: Wed Sep 19, 2001 7:47 pm

RE: Air-to-Air Refuelling Fuel Spoilage

Thu May 30, 2002 11:43 pm

I don't know what happens when the fuel dries, shouldn't be too much of a problem I think, but indeed, to avoid problems most receptacles are found behind the cockpit.

Something I have been thinking about: what if you would have an intake on the back of your aircraft (a la Global Hawk) and a refuelling receptacle at the back of the aircraft as well. Would fuel spoilage be a problem then? Concerning fuel ingestion in the engine for instance. Will the engine blow up? Or will it just experience some sort of hickup and continue operating flawless?
 
bsergonomics
Posts: 458
Joined: Thu Jan 31, 2002 5:07 am

RE: Air-to-Air Refuelling Fuel Spillage

Fri May 31, 2002 1:03 am

I understand that, while not ideal, a small amount of fuel entering the engines is nothing to worry about. Only a large amount, resulting from an uncontrolled spillage, would be enough to worry about. That said, engines aren't my bit so don't quote me on that.

However, in relation to the A-10, there is a known issue with spillage after AAR. The area that is covered by the fuel includes the intake for the pilot's oxygen system (I'm not aware exactly which type of system this is). This means that a spillage after AAR can lead to fuel fumes in the oxygen system, which can, in turn, lead to hypoxia.

This theory was considered for a long time before finally being rejected as being a primary cause of an A-10 crash a few years back. Essentially, the pilot lazily flew around for quite a while before parking his plane in a hill. Both pilot and plane were written off. The detailed description of his flying style reminded many of the actions of a hypoxic, but (if I remember correctly), the BOI finally concluded that it was a deliberate act.

I'm afraid I'm a bit hazy and I'm sure that some of you are far more informed than I, so please feel free to correct or add details.
The definition of a 'Pessimist': an Optimist with experience...
 
Lt-AWACS
Posts: 2120
Joined: Mon Jan 14, 2002 2:40 am

RE: Air-to-Air Refuelling Fuel Spillage

Fri May 31, 2002 1:14 am

It is more fun to watch us dump 20,000pounds of fuel over lake Draper in Central Oklahoma. Streaming fuel for miles  Smile on an almost daily basis.


Ciao and Hook 'em,
Lt-AWACS
Io voglio fica ogni giorni da mia bella moglie!
 
ExitRow
Posts: 1630
Joined: Mon Aug 13, 2001 7:13 am

RE: Air-to-Air Refuelling Fuel Spillage

Fri May 31, 2002 6:39 am

Doesn't most spilled/dumped fuel aerosolize and evaporate?
 
Lt-AWACS
Posts: 2120
Joined: Mon Jan 14, 2002 2:40 am

RE: Air-to-Air Refuelling Fuel Spillage

Fri May 31, 2002 10:13 am

yes but the locals don't know that and they freak out when they hear about it Smile I know some old guys who refuse to fish in Lake Draper because of it

Ciao and Hook 'em Horns,
Lt-AWACS
Io voglio fica ogni giorni da mia bella moglie!
 
EssentialPowr
Posts: 1646
Joined: Wed Sep 06, 2000 10:30 pm

RE: Air-to-Air Refuelling Fuel Spillage

Fri May 31, 2002 10:52 am

This topic has come up before, and someone inevitably claims that the fuel evaporates. This in turn incorrectly implies that the process of evaporation, a phase change, means the substance "disappears", but that doesn't even pass the common sense test.

Further, if one pours a thin layer of jet fuel in a pan, will it even evaporate like gasoline or water? No.

Dumped fuel is atomized by the slip stream. The atomized fuel is carried by winds and dispersed, but eventually it settles to the surface.

 
Lt-AWACS
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Joined: Mon Jan 14, 2002 2:40 am

RE: Air-to-Air Refuelling Fuel Spillage

Fri May 31, 2002 11:14 am

yes but I think his point was more like does it 'Rain' down below if you dump at 20k and the answer is no. Usually we dump over water anyway and by the time the fuel settles it is no factor according to the EPA.

Ciao and Hook 'em Horns,
Lt-AWACS
Io voglio fica ogni giorni da mia bella moglie!
 
EssentialPowr
Posts: 1646
Joined: Wed Sep 06, 2000 10:30 pm

RE: Air-to-Air Refuelling Fuel Spillage

Fri May 31, 2002 11:45 am

Do you have a reference on the EPA's position?
 
Lt-AWACS
Posts: 2120
Joined: Mon Jan 14, 2002 2:40 am

RE: Air-to-Air Refuelling Fuel Spillage

Fri May 31, 2002 1:11 pm

not other than what the Documents the Flight Engineer fills out everytime we dump fuel. That goes to some office on at the Wing level who deals with the EPA (and a state agency if we are in Oklahoma) The EPA always signs off on it so it has never been a problem. Lake Draper is the desingnated dump spot for Tinker anyway.


Ciao and Hook 'em Horns,
Lt-AWACS
Io voglio fica ogni giorni da mia bella moglie!
 
EssentialPowr
Posts: 1646
Joined: Wed Sep 06, 2000 10:30 pm

RE: Air-to-Air Refuelling Fuel Spillage

Fri May 31, 2002 2:47 pm

How often do you dump fuel?
 
TurbineBeaver
Posts: 1511
Joined: Fri Jan 11, 2002 1:50 am

RE: Air-to-Air Refuelling Fuel Spillage

Fri May 31, 2002 11:16 pm

It sounds like it'd be pretty cool to witness, but WHY are you dumping 20,000 lbs of fuel everyday!?!? Hell, if you don't need this fuel, send it to me, my family will be VERY appreciative, it'll keep our planes fueled for quite some time!  Big thumbs up

TB
 
EssentialPowr
Posts: 1646
Joined: Wed Sep 06, 2000 10:30 pm

RE: Air-to-Air Refuelling Fuel Spillage

Sat Jun 01, 2002 12:03 am

Agree. I guess my point is that, dumping fuel in part 121 ops almost always coincides with an emergengy. I don't see how a single KC135/AWACs crew should need to be dumping 20,000 lbs "on an almost daily basis". That's just poor fuel management, and I have a suspicion that the EPA would be much more concerned than what ltAwacs implies.
 
Lt-AWACS
Posts: 2120
Joined: Mon Jan 14, 2002 2:40 am

RE: Air-to-Air Refuelling Fuel Spillage

Sat Jun 01, 2002 2:06 am

not everyday more like everyweek if that makes you feel better, but I've seen 20k dumped off the Carolina's several times and also on emergency around the US, but Emergencies are quite common, especially since the ops tempo went up. It is not the fuel management but more on the fighter side. If activity falls out or we have to come home early and the Okie winds or rain kick, the Fuel goes bye-bye to meet landing specs.

Ciao and Hook 'em Horns,
Lt-AWACS
Io voglio fica ogni giorni da mia bella moglie!
 
EssentialPowr
Posts: 1646
Joined: Wed Sep 06, 2000 10:30 pm

RE: Air-to-Air Refuelling Fuel Spillage

Sat Jun 01, 2002 2:16 am

That sounds more reasonable.

cheers-
 
L-188
Posts: 29881
Joined: Wed Jul 07, 1999 11:27 am

RE: Air-to-Air Refuelling Fuel Spillage

Sat Jun 01, 2002 8:35 am

Is that A-10 crash that guy that was out of Davis Monthan and then ended up in a mountain in Colorado a couple a years ago.
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