What happens to dumped fuel?

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Wingsofglass

Pre-takeoff checklist
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Wingsofglass
A while back I was on an IFR flight and high above me, ATC was talking to a UPS plane that was dumping fuel. Earlier today I was reading about an Air Canada 777 that lost an engine on takeoff and circled dumping fuel before landing. Does anyone know what happens to dumped jet fuel? Does it evaporate before reaching the surface? And if so, how much altitude do you need before it evaporates?
 
It usually evaporates into the atmosphere. Not sure what altitude you have to be at but when we were in 727 school we were taught that it could dump fuel at a rate of 300#/min per operating boost pump or put another way, 2300# per min with all of the pumps running. That's a lot of gas in a short period of time pumped overboard.
 
HPNPilot1200 said:
It usually evaporates into the atmosphere. Not sure what altitude you have to be at but when we were in 727 school we were taught that it could dump fuel at a rate of 300#/min per operating boost pump or put another way, 2300# per min with all of the pumps running. That's a lot of gas in a short period of time pumped overboard.
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You don't have to be very high when you dump with the AB burning.

It is impressive when the RA5C dumps 1800 gallons and hits the burner.
 
If it's up high, it will atomize into the atmosphere. If you dump when down low, some of it will reach the ground. Of course, if you are dumping while down low, things are bad and the least of your concern is where the fuel goes. If there is time some ATC facilities have places where dumping is preferred, such as offshore, but in an emergency the PIC has final authority and responsibility to the safety of the flight.

Some airlines/operators have policies for min jettison altitudes, but PIC can override that. This guy dumped fairly low and I believe the mayor of the town was upset about it, but I think the pilot was probably doing NJ a favor! :D

http://www.youtube.com/watch?v=uoUBWEqPu0Q

Relatively useless knowledge, but the 777 can dump at about 5400lb/hr (that slows to 3000 and change when the center tank empties) plus whatever the engine(s) are burning. Not a bad way to lose some weight, but when the max landing weight is close to 200,000lbs lower than max takeoff, it can take a while!
 
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Rex Kramer said:
Relatively useless knowledge, but the 777 can dump at about 5400lb/hr (that slows to 3000 and change when the center tank empties) plus whatever the engine(s) are burning. Not a bad way to lose some weight, but when the max landing weight is close to 200,000lbs lower than max takeoff, it can take a while!
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5400# per hour? That's pretty slow!
 
Our dump rate in the 747 is about 6000 lbs/minute with all six jettison-override pumps running. Without center wing fuel, that drops to four pumps and approximately 4000 lbs/minute.

Our takeoff this morning was 697,314 lbs; we need to be at 630,000 lbs for landing weight. An engine failure on takeoff mean that we'd have had a 17 minute dump time to get down to our landing weight, based on no centerwing fuel and four jettison-override pumps to push the fuel overboard.

Dumped fuel atomizes and evaporates.

A thread recently took place on pilots of america about fuel dumping.
 
I have an idea. I'm going to invest in a million gallon API spec steel tank near LAX and put a big sign on the top saying "free fuel dump."

Probably not a huge environmental concern, but holy crap, look at all that money dissipating in thin air.
 
Sac Arrow said:
I have an idea. I'm going to invest in a million gallon API spec steel tank near LAX and put a big sign on the top saying "free fuel dump."

Probably not a huge environmental concern, but holy crap, look at all that money dissipating in thin air.
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Yeah, but that usually only happens in a dire emergency.
 
Rex Kramer said:
If it's up high, it will atomize into the atmosphere. If you dump when down low, some of it will reach the ground. Of course, if you are dumping while down low, things are bad and the least of your concern is where the fuel goes.
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I think I would disagree. I would think it is a great concern to make sure that as little fuel as possible makes it to the fire. :mad3:
 
Sac Arrow said:
I have an idea. I'm going to invest in a million gallon API spec steel tank near LAX and put a big sign on the top saying "free fuel dump."

Probably not a huge environmental concern, but holy crap, look at all that money dissipating in thin air.
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That would be an API 650 tank. (just for your fund of trivial knowledge)
 
Clark1961 said:
That would be an API 650 tank. (just for your fund of trivial knowledge)
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Actually, I was thinking of an API 12B, which is a bolted steel tank as opposed to a 650 welded steel tank, but yes that would be fine too.
 
Sac Arrow said:
Actually, I was thinking of an API 12B, which is a bolted steel tank as opposed to a 650 welded steel tank, but yes that would be fine too.
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Haven't seen a new bolted tank in years...wouldn't want to either!
 
Sac Arrow said:
Some advantages. Factory bonded epoxy and glass coatings. Cheaper in the smaller sizes too.
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We only have a couple places where we use coatings. If liquids are corrosive then we try real hard to not use carbon steel at all. We buy a lot of 13Cr tubulars and make sure the liquids are non-corrosive by the time they get to storage.
 
Tom-D said:
You don't have to be very high when you dump with the AB burning.

It is impressive when the RA5C dumps 1800 gallons and hits the burner.
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Vigilante?? It has been a long time. We carried Heavy 7 on the Enterprise on every deployment that I was on.
 
Graueradler said:
Vigilante?? It has been a long time. We carried Heavy 7 on the Enterprise on every deployment that I was on.
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My cousin spent his whole career in vigi's, I always teased him about his detailer hating him.
 
As far as dumping down low, it indeed does not vaporize. The hornet that went down in VA Beach last month sprayed fuel all over the place.


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hopmedic said:
I think I would disagree. I would think it is a great concern to make sure that as little fuel as possible makes it to the fire. :mad3:
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I dunno, I consider it a higher priority to get the weight down so I don't end up in a ball of fire of any size...
 
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