The only routine requirement for defuelling is maintenance. For example, scheduled fuel tank maintenance or an aircraft reweigh are the two most likely situations I can bring to mind.
Where such maintenance is programmed, flight crews would be requested to RTB with minimum fuel. For some aircraft, offloading fuel is a considerable nuisance.
concur, not only is it a nuisance offloading, in most places, the fuel cannot be re-loaded onto another ac....so a special truck must offload it and it must go back to the fuel farm and set through the filtration system....
I have never heard of a fuel farm accepting "used" / contaminated fuel into its system...?! After all, the fuel has to be considered "out of specification". Or do I miss something?
In my experience, fuel removed from an aircraft goes either back into the same airplane (after weighing or tank entry accomplished), into an airplane of the same operator - or to a power plant...
Well, I did say if..... once if off the aircraft, it is not going into another aircraft untreated.
There are many facilities that have above ground storage tanks, that are even filled by trucks, so there is a filtration system to handle green fuel.
Even so, there is little spec difference between jet fuel and kerosene heating oil for a home....except the cost, and filtration and water content on delivery...
If you dont think that is true, there are lengthy discussion about this on this website... here we go...
Where I work, fuel that is removed from an aircraft can only be re-used within the same airline. If airline procedures do not permit 'recycled' fuel, it's trucked off to wherever and discarded.
In my point of view (mechanical) filtration is not enough, as per legal aspects.
Thank you for the link to A1, not much new things there....
What you pump out of an aircraft tank (especially long range airplanes) is a wild mixture of Jet A, Jet A1, TS-1; there is an unknown part of microbial contaminants like yeast, fungus etc., sand, water, hydraulic fluid, left-overs of previous tank entries - well, just about anything...
The bottom line: In MY aviation world, we can only bring material to an aircraft with proper documentation about what the stuff is (Form 1s, Conformity Statements etc.). Any fuel that has gone through an aircraft tank is per default not in line with any of the AFM approved fuel specifications and therefore out of the game (with the exceptions given in my previous post).
On the recent BBC programme about the full maintenance job on a B747 it showed the presenter and a technician inside a fuel tank without breathing apparatus. I was surprised at this, as even if the tank was emptied it would have a lot of residue left in. (I have a little knowledge of this from driving road tankers around delivering kerosene many years ago).
I can't comment on current H&S legislation, but I've crawled into plenty of tanks in my time with nothing more than a socket spanner and a wander light.
The tanks would have been inerted with carbon dioxide before entry...
There should not be any residue, as the fuel and slosh would keep the interior very clean...
There will be a problem with biofuel, if you ever use it, it is very clean, and will flush out all the intake lines, expect to be changing filters quite often when you first start using that stuff, if ever..
Last edited by FlightPathOBN; 17th Jul 2012 at 21:50.
Carbon dioxide? You may have been more believable guessing it was laughing gas.
In the UK, wet tanks can be entered with Breathing Apparatus otherwise the tank is drained, forced air vented and entered without BA after the tank atmosphere is checked (electronically-not with canary's, even in Wales) continuously for remaining vapours.
The tanks would have been inerted with carbon dioxide before entry...
This doesn't make any sense at all to me.
Here's the basics of how tank entry is done where I work. Before entry the tank is defueled/sumped then purged using blowers and venturis to obtain the correct Lower Explosive Limit and oxygen content. This is considered a fire-safe condition and allows for entry using a supplied air respirator. Repairs can then be performed or the people entering the tank will remove any remaining fuel and the tank will continue to be purged until the health-safe limit has been reached which allows entry without respirator, although its still recommended. If the tank contained JP-4 or Jet B a health-safe condition is not possible (not an issue for me). During the whole process the tank is continuously monitored and ventilated.
