luftaom
Posts: 525
Joined: Thu May 20, 1999 4:29 pm

Fuel Dumping

Wed Jun 09, 1999 12:42 pm

whats the procedure for dumping fuel does the crew have to advise the fuel dump to someone, or do they just do it.

and the actual jettisoning of the fuel itself i know on the 747 there is a nossle towards the end of the wing on either side, but what is the procedure in the cockpit and what buttons have to be pushed?

Under what circumstances can/is it dumped?

If anyone has any pictures on this issue I would be most greatful
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Yeah cheers, thanks a lot!

Best Aviation Minded Regards

Bradley
 
stlbham
Posts: 438
Joined: Mon May 24, 1999 11:24 am

RE: Fuel Dumping

Wed Jun 09, 1999 1:09 pm

Im not to sure of the procedures on the fuel dumping, but i think that it has to be granted atc. Im not sure on this...... But i know of a picture on here go to keyword and its 30316, its not too good but does show the fuel dumping process.
 
JETPILOT
Posts: 3094
Joined: Tue May 18, 1999 6:40 am

RE: Fuel Dumping

Wed Jun 09, 1999 4:12 pm

The information I am supplying is type specific for the DC8 50 sereies.

The DC8's Fuel dump system is gravity fed dump system.

The DC8 consists of a 10 tank system. 2 fuselage tanks(a center and foward aux) and 8 wing tanks. One main and one alt tank per engine.

The forward center aux (9015 pds) gravity feeds into the center aux tank (28310 pds) The center wing aux is then gravity fed into the fuel dump manifold.

Also connected to the fuel dump manifold are the 8 main and alternate tanks. Which are also gravity fed into the fuel dump manifold. The fuel dump manifold is connected to retractable dump shoots that extend down about 4 feet when extended to clear the bottom of the flaps at the 25 degree position.

The fuel dump limitations are airspeeds of 167 min (minimum flap manouvering speed for flaps 25) and 260 max (maximum flap extension speed). With max flap extension of 25 degrees the dump chutes are extended in the cockpit either electrically or mechanically in case of electrical failure. One the chute has reached the fully extended position a mechanical actuator opens the fuel dump valves for all the tanks except the foward aux which dumps it's contents into the center wing aux and is not directly fed into the dump manifold.

The fuel dump rate is 4000 pounds per minute. The DC8 has a max fuel load of 120,000 pounds. In order to dump a predetermined amount of fuel the dump must be timed.

All the fuel on board cannot be dumped. Located in the main tanks is a standpipe. When the fuel drains below the top of the standpipe no more fuel will exit the 4 main tanks. This fuel remaining in the 4 main tanks will allow you to climb from sea level to 10,000 feet and fly for 45 minutes thereafter at long range cruise power settings. Only the main tanks have standpipes the alternates and aux tanks can be drained completely.

The fuel is dumped for emergencies only. Either to get the plane below the maximum landing weight, or to jetison all dumpable fuel in order to lesson the chance of a conflagration on a catastrophic landing. The crew has to advise no one of the fuel dumping. However if the crew is dumping fuel there is something far worse happening to the aircraft.



 
luftaom
Posts: 525
Joined: Thu May 20, 1999 4:29 pm

RE: Fuel Dumping

Wed Jun 09, 1999 6:34 pm

great thanks

cheers

Bradley
 
JETPILOT
Posts: 3094
Joined: Tue May 18, 1999 6:40 am

No Problem ! (nt)

Thu Jun 10, 1999 2:50 am

>
 
cedarjet
Posts: 8101
Joined: Mon May 24, 1999 1:12 am

RE: Fuel Dumping

Thu Jun 10, 1999 2:51 am

I know that the 757 doesn't have fuel-dumping capability. Some countries don't like it over land, Canada being one - they were in the process of advising the Swissair MD11 when they could start dumping (ie after they'd got over the coastline) when the fire suddenly broke out behind the cockpit (until that point there'd been only smoke), at which point they started dumping anyway, even though they hadn't quite cleared the coast. I presume the dumped fuel disperses but I have a set of MEA 707 checklists that proscribe flying in circles while dumping, and there is a specific reference to the danger of flying through the trail of dumped fuel. A friend of mine was the co-pilot on a 707 that suffered a major structural failure over the Alps, both engines on the right wing seperated, took out flaps, hydraulics and started a fire in the wing. They started dumping fuel, they'd actually taken off above max t/o weight so there was a lot of fuel to get rid of (flight was Luxembourg to Entebbe, Uganda), but the fire got worse and they had to shut the dump valves. Twenty minutes later they made a downwind landing at 220 kts at a French AFB called Istres and jumped out the cockpit windows as the wreckage exploded.
fly Saha Air 707s daily from Tehran's downtown Mehrabad to Mashhad, Kish Island and Ahwaz
 
Guest

RE: Fuel Dumping

Fri Jun 11, 1999 2:20 am

You are correct about the 757 not being able to jettison fuel while airborne, Cedarjet. I remember being very surprised at that fact in mtc training.

Regarding the MD-11, it is completely automated. A single button on the overhead Fuel System Control Panel is pressed to start dumping. The system will automatically dump fuel until the max landing weight is reached. The fuel is dumped under the power of the transfer pumps which pump fuel into the fuel dump manifold. Electrically powered sliding gate valves are opened to allow the fuel to be dumped from there. The valves are springloaded to a failsafe closed position. They will not open, or remain open without power. In the event of a system failure, and the valves do not close when maximum landing weight is reached, there is an emergency dump stop switch on the overhead control panel to power actuators which close the valves. Fuel is dumped at a rate of 5000 lbs a minute.

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