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Transferring Flammable Jet Fuel  
User currently offlinefsnuffer From United States of America, joined Jun 2007, 252 posts, RR: 0
Posted (3 years 7 months 2 weeks 3 days 19 hours ago) and read 4001 times:

What could go wrong

http://www.military.com/video/milita...ing-aerial-refueling/813012158001/

6 replies: All unread, jump to last
 
User currently offlinetitanmiller From United States of America, joined May 2006, 90 posts, RR: 0
Reply 1, posted (3 years 7 months 2 weeks 3 days 16 hours ago) and read 3931 times:

Boom operator here,

That's a very impressive video for sure. I ran across it a few months ago on Youtube and now use it as an instructional aid for my students while discussing refueling during adverse weather. This type of static discharge is caused when the aircraft fly through certain atmospheric conditions capable of charging the airframe, typically ice crystals (as in the creation of lightning) in clouds or light atmospheric dust. The effects seem to be the most pronounced when the tanker and receiver are considerably different in size or shape since they will generate charge at varying rates. From my experience, C-130 receivers are the most prone to this phenomenon, presumably due the lower refueling altitudes that they fly at.

As for the risk of fire; there really isn't any concern since there isn't any fuel present prior to contact, and the two aircraft are grounded through the boom while in contact. If there was a substantial fuel leak from the boom nozzle at the same time that there was a spark, then I think it is conceivable that a fire might be possible in the same way that the RAAF F-111 could do the dump & burn routine. It really isn't likely or even possible, and to the best of my knowledge it has never been recorded, not even a single flame.

The spark itself could probably erode the metal surface, but I haven't heard any reports of this either.

With that being said, this video is a thousand times more intense than anything I have seen in person. Normally, it is just a small 1 or 2 inch spark that lasts a few milliseconds prior to contact (like touching a doorknob except bigger).

[Edited 2011-03-08 19:45:58]

[Edited 2011-03-08 19:46:24]

[Edited 2011-03-08 19:46:38]

User currently offlineunattendedbag From United States of America, joined Oct 2003, 2328 posts, RR: 1
Reply 2, posted (3 years 7 months 2 weeks 3 days 16 hours ago) and read 3920 times:

Quoting titanmiller (Reply 1):
As for the risk of fire; there really isn't any concern since there isn't any fuel present prior to contact, and the two aircraft are grounded through the boom while in contact.

what about after fueling has concluded and the boom is being retracted? I have seen in videos, excess fuel spray coming from the boom as it pulls away.



Slower traffic, keep right
User currently offlinetitanmiller From United States of America, joined May 2006, 90 posts, RR: 0
Reply 3, posted (3 years 7 months 2 weeks 3 days 16 hours ago) and read 3916 times:

Quoting unattendedbag (Reply 2):
what about after fueling has concluded and the boom is being retracted? I have seen in videos, excess fuel spray coming from the boom as it pulls away.

One thing to remember is that immediately after disconnect, the two aircraft do not have any voltage difference since they were just grounded to each another. It will take a certain length of time for that potential difference to form.


User currently offlineKC135TopBoom From United States of America, joined Jan 2005, 12158 posts, RR: 51
Reply 4, posted (3 years 7 months 2 weeks 3 days 6 hours ago) and read 3799 times:

Quoting unattendedbag (Reply 2):
what about after fueling has concluded and the boom is being retracted? I have seen in videos, excess fuel spray coming from the boom as it pulls away.

Actually it really isn't that much fuel that sprays upon disconnect, about 1 qt. (1 L.), in the Boom spring loaded poppet valves closes correctly.

titanmiller is right, usually you get the most Saint Elmo's fire with slower receivers, like the C-130 and A-10, while refueling in weather. But, as in the video it does happen with large or heavy receivers like that E-4B. I have seem it with B-52, EC/RC/KC-135, KC-10, E-3, E-8, C-5, C-141, etc.

But to answer your original question, the fuel or fuel vapors coming from the receptical or nozzle are just to lean a mixture to catch fire due to the airspeed of the refueling. Remember the airflow around the tanker and receiver is at least 185 KIAS of wind, up to 335 KIAS of wind. Depending on actual wind speed and direction at the refueling altitude, that is a TAS of anywhere between about 220 knots and 500 knots.

[Edited 2011-03-09 06:28:31]

User currently offlinegeezer From United States of America, joined Aug 2010, 1479 posts, RR: 2
Reply 5, posted (3 years 7 months 6 days 15 hours ago) and read 3321 times:

This isn't about airplanes, but it is about Avjet A; back in the early 1960's I drove a tank truck for Texaco, out of Cincinnati, Ohio. We hauled two grades of of gasoline to service stations, and three different aviation products to airports, mostly CVG, ( which is right across the Ohio River from Cincinnati ) At this point in time, the big Jets were just coming along, and we had to use aluminum tankers to haul Jet A. At the time, AA was still using DC 6 B's, ( which burned 100 /130 av gas, which is green ), Delta still operated the DC 7, and they used 115 / 145 av gas, which was purple; in the first year of the Jets, there were only 6 arrivals and departures per day, by TWA, and they used the Jet A ; before you can off-load any av fuel, you must call ground service, and they have to take samples for the lab, then test it for water and Sp. gravity.

Now, everyone knows how volatile gasoline is..........VERY ! But it is actually safer to handle that Jet a. Gas has a very low flash point, ( app. 85 to 100 Deg F ) and jet a is about 130 to 140 degrees, which we all just "assumed" made it "safer";
Here's how I got my big "education" about that;

I bid off the tankers and started running the loading rack; ( big roofed over platform about 10 - 11 ft high, with room on either side for two tank trucks to load at the same time; most tankers have 6 compartments; you stick the 4" dia. aluminum loading riser in the top hatch, set the auto shut-off meter to the gallons you want, pull the laver back, and it puts the gasoline in at the rate of 600 gallons per minute, then shuts off automatically when the gallons "set" is loaded;

normally you have 2 risers going at once, in each truck, and usually 4 trucks at a time. So that's about 4,800 gal / min. going in the 4 trucks. Before you ever even stick a riser pipe in a hatch, you attach a bonding cable to the trailer, and it has a 1/2 " braided bronze cable running down to copper ground bar. One of my many "functions" was to keep repairing all the bonding cables that the drivers tore off by "forgetting" to take the ground clamp off before pulling away.
What I was unaware or, even though we had the ground clamp attached, the cable was broken, so we were loading without benefit of grounding.
Near the end of the shift, the drivers came in, parked under the loading rack, and I had to load all 6 or 8 trucks for the next shift; ( most of the Texaco trailers back then were 7,000 gallon; some carriers had 9,000 trailers, and so on. )

So, on the "big night", ( I had just returned that day from 2 weeks vacation ), I was loading 3 gasoline trailers, and John Vanderpohl came in for his last of four loads of av jet, for TWA. I had 6 risers running, and John had one compartment on his trailer loaded, had just removed the riser and stuck it in the 2nd compartment; pulled the lever, the Jet a was running, and he's standing on top of his trailer, and I'm standing on the platform, about 5 ft away; What I haven't mentioned yet is, when you have 600 gal / min of gas or jet a going in a trailer, it creates one HELL of a lot of static ! ( hence the grounding cables ) And what I was "unaware of", while I was off on vacation, the"schmucks" doing my job never got around to repairing the ground cables that the drivers tore off . So.......we're "chatting", ...........all of a sudden as John had just got the product running, there was a spark ! ( caused by static ) to say that I was "incredulous" would be a gross "understatement"; my first "act", was to grab a nearby 40 lb Ansul bottle to attempt to "save the day"; I discarded that "idea" after only about 2 steps; it was maybe 30 ft to the fire door at the end of the rack, and the damned thing actually opened towards you ( whch we later found is extremely "illegal", so I just "ran", straight to the side of the rack, jumped clear over the tank truck, sailed 15 ft through the air, and landed on concrete. To say it was a hard landing, would be another big "understatement". The whole loading rack burned down, all 4 trucks under the rack burned down, plus 2 more waiting behind them. The entire Cincinnati Fire Dept. was there pretty shortly, and they realized they had a BIG problem ! They didn't have a CLUE how to fight a fire like this; all while this is going on, all that fuel is still going into all 4 trailers; when the Fire Chief arrived, I pointed out to him that "if you think THIS is a fire, wait till those tanks in the tank farm start burning, then you'll see a real fire ! ( two i million gal gasoline tanks, three 650,000 gal Jet a tanks, and about a dozen more; So the Fire Chief says; "who the hell knows where all this damned fuel is coming from, and how the hell to shut it off ? So I said, "well, this time of night there is just one guy, and you're talking to him, but I have an extremely sore "everything" just now ! So instead of going to the hospital, I had to stick around and show the firemen which tanks were running, and how to close the shipping valves to get the fuel shut off.

This huge fireball was about 75 to 100 ft from the nearest storage tank, which thankfully contained #2 fuel oil

Needless to say, there was a huge "flap" over the whole thing; just as the cops were about to "transport" me, the plant manager shows up; It's ALL MY FAULT ! I'm the goat here ! Then, one of the luckiest things in my life happened; unbeknown to me at the time, there was a very high "muckety muck" from Texaco Corporate visiting, and he was staying in a motel right down the street ; he got to the scene half an hour before the plant mgr, and had been talking to the Fire Chief for a while; When the "Boss" was screaming and yelling and blaming the whole thing on me, this BIG GUY from New York steps up, looks at the Plant Manager, and calmly says; .........."Why Mr. Smith, you are talking / screaming at the man that just saved this entire plant from burning to the ground !"


A few weeks later, all these engineers started decending on the place, and that's when I got my "education" about Av jet A; yes, it has a much higher flash point, but it is also about 4 times as "vulnerable" to creating static. And when you have a lot of flamable products around, you don't NEED any static ! So don't ever think that av jet is "safer" than gasoline; much less "volatile", much higher flash point, but the stuff creates static 4 times as fast as gasoline.
You'd kinda think a big company like Texaco would have given employees who handle this stuff every day, a little training wouldn't you ?

Charley



Stupidity: Doing the same thing over and over and over again and expecting a different result; Albert Einstein
User currently offlineKC135TopBoom From United States of America, joined Jan 2005, 12158 posts, RR: 51
Reply 6, posted (3 years 7 months 6 days 6 hours ago) and read 3233 times:

Quoting geezer (Reply 5):
geezer

An increditable story, geezer. You and your co-workers are lucky no one was killed. A Jet-A, or JP-4 fire spread very fast. JP-5 is only slightly safer, but does not have the deicing stuff JP-4 had. JP-8 used today is even safer, but when it does catch fire burns even hotter.

Jet fuel, of any type is also known as "wide cut gasoline", and kerosine. It is much more "sticky" than gasoline as it retains the oily substance that is used to lubercate the parts of the engines, fuel pumps, manifolds, and tanks.


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