Trent800 From Belgium, joined Sep 2001, 9 posts, RR: 0 Posted (11 years 6 months 1 week 4 days 16 hours ago) and read 3267 times:
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 From United States of America, joined Apr 2002, 1322 posts, RR: 3 Reply 1, posted (11 years 6 months 1 week 4 days 13 hours ago) and read 3235 times:
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 From Belgium, joined Sep 2001, 9 posts, RR: 0 Reply 2, posted (11 years 6 months 1 week 4 days 11 hours ago) and read 3229 times:
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 From United Kingdom, joined Jan 2002, 462 posts, RR: 0 Reply 3, posted (11 years 6 months 1 week 4 days 10 hours ago) and read 3195 times:
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...
EssentialPowr From United States of America, joined Sep 2000, 1820 posts, RR: 2 Reply 7, posted (11 years 6 months 1 week 4 days ago) and read 3149 times:
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 From , joined Dec 1969, posts, RR: Reply 8, posted (11 years 6 months 1 week 4 days ago) and read 3149 times:
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.
Lt-AWACS From , joined Dec 1969, posts, RR: Reply 10, posted (11 years 6 months 1 week 3 days 22 hours ago) and read 3134 times:
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.
TurbineBeaver From United States of America, joined Jan 2002, 1199 posts, RR: 0 Reply 12, posted (11 years 6 months 1 week 3 days 12 hours ago) and read 3112 times:
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!
EssentialPowr From United States of America, joined Sep 2000, 1820 posts, RR: 2 Reply 13, posted (11 years 6 months 1 week 3 days 11 hours ago) and read 3110 times:
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 From , joined Dec 1969, posts, RR: Reply 14, posted (11 years 6 months 1 week 3 days 9 hours ago) and read 3092 times:
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.