soaringadi
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Is It That Necessary To Dump Fuel?

Sat Oct 16, 2004 1:56 am

My question here is regarding the huge airliners which always dump fuel in case of an immediate emergency landing. I wanted to know if they could land without dumpping fuel ? I know it will be way heavier, and thus greater speed, and therefore marginal operation with things such as the landing gear, flaps etc. But is it at all possible ?

Thank you  Smile
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LimaFoxTango
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RE: Is It That Necessary To Dump Fuel?

Sat Oct 16, 2004 2:28 am

Yes it is possible to land without dumping fuel first. However, doing so would exert way too much stress on the landing gears and would be serious maintainance issue. The only time in my opinion a 747 for example, would land with a full load just after takeoff, is if all 4 engines caught fire. Now come on, how often does that happen? So in any emergency, there's always time to dump fuel.

However, in a 737 for example, that doesnt have a fuel dump system, they'll just have to fly around for 2+ hours to burn fuel before landing if they want to save their landing gears.
You are said to be a good pilot when your take-off's equal your landings.
 
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longhauler
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RE: Is It That Necessary To Dump Fuel?

Sat Oct 16, 2004 3:18 am

Every western built transport is certified to land right up to its maximum takeoff weight, even if well above maximum landing weight. An "overweight landing" checklist must be performed before landing, and also Maintenance must perform an "Overweight Landing" inspection before the aircraft can fly again.

That being said, there are however, many circumstances that might dictate a fuel dumping precedure, if so capable, and if time permits, before landing. Oddly enough, they are not structural considerations, they are performance considerations. For example; landing on a short contaminated runway, or single-engine go-around performance, or special procedure airports, or landing with a flap configuration less than optimal. These would dictate consideration to reducing landing weight if the aircraft is so equipped.

Most (there are always exceptions) smaller, newer aircraft are not equipped with fuel dumping capability... the B737 or the A320 series for example. Some B767s are so equipped, some are not!

Remember, one can always land at a weight right up to maximum takeoff weight!
Just because I stopped arguing, doesn't mean I think you are right. It just means I gave up!
 
rendezvous
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RE: Is It That Necessary To Dump Fuel?

Sat Oct 16, 2004 7:27 am

An incident happened in Sydney a couple of years ago. British Airways 747-400 went out to Singapore (or Bangkok), it had a fire in the forward cargo hold about 20min into flight. It declared mayday and came back and landed immediately without dumping fuel. It was an overweight landing followed by a full evacuation.

In a full emergency your priority is safety - if it is safer to get on the ground and maybe damage the plane a bit, so be it, it's obviously better than the plane burning up in the air and crashing. If you have a situation such as the photo below where it's good to get back, but you're not going to crash if you spend a few minutes dumping fuel, then save the plane too.


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Photo © Dna

 
AAR90
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RE: Is It That Necessary To Dump Fuel?

Sat Oct 16, 2004 11:58 am

...which always dump fuel in case of an immediate emergency landing.

I'd say your premis is wrong. In most instances of an emergency shortly after takeoff the crew is dumping fuel to improve acft flight performance or reduce the risks during the subsequent emergency landing. It is wrong to say "always" as many airliners are not even equipped with a fuel dump system and many "emergencies" don't require fuel dumping.

However, in a 737 for example, that doesnt have a fuel dump system, they'll just have to fly around for 2+ hours to burn fuel before landing if they want to save their landing gears.

Naw, just land it very softly... (I landed a max gross weight 738 just 10 minutes after takeoff following a bird strike --probably the softest landing I've ever made in that plane even if it was at 200+ knots).  Wink/being sarcastic
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PhilSquares
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RE: Is It That Necessary To Dump Fuel?

Sat Oct 16, 2004 12:11 pm

I have landed an aircraft about 11 minutes after takeoff way over it's landing weight. Had taken off out of SHJ and had an engine fire which would not extinguish. Had enough time to go out and do a 180 and return to land. No big deal. Brakes were a little warm, but certainly beat the options.

Forgot to add we were about 100 tons above Max Landing Wt.

[Edited 2004-10-16 05:12:16]
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HeavyCapt
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RE: Is It That Necessary To Dump Fuel?

Sat Oct 16, 2004 1:30 pm

Remember, one can always land at a weight right up to maximum takeoff weight!

Not exactly true...Western built and Certificated aircraft must have a Fuel Dump System installed if their MGTOW is 105% or more of their MLW. (Check the FARs). Aircraft such as the 737, and 767 don't have dump systems as they aren't required due to their take-off and landing weights.

 
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longhauler
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RE: Is It That Necessary To Dump Fuel?

Mon Oct 18, 2004 12:33 am

I don't think I quite follow you.

The A320 that I fly, has a MGTOW of 75,500 kgs, yet a MLW of 64,500Kgs, and has NO fuel dump system ... and ... if the need arises, we may land right up to 75,500 kgs.

Same thing with the A319s and A321s that I fly, the MGTOW is much more than 105% above MLW, and none are equipped with a fuel dump system.

We do however, have an "overweight landing" procedure for all.
Just because I stopped arguing, doesn't mean I think you are right. It just means I gave up!
 
Rick767
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RE: Is It That Necessary To Dump Fuel?

Mon Oct 18, 2004 7:15 am

As has been noted, all modern western aircraft are certified to land up to MTOW in an emergency (i.e. in excess of MLW).

We had a 763 in Britannia a couple of Summers ago which landed 40,000kg (about 88,000lbs) overweight operating a MAN-SFB flight, after smoke in the cabin after departure.

Nice landing by the skipper, and after the overweight landing inspection which revealed no damage, and a fix for the smoke issue the aircraft was on her way again 2 hours later, courtesy of a standby crew comprising yours truly  Big grin

I have also landed a 757-200 overweight (can't dump the fuel on those birds, as with 737s and A320s).

Another factor to consider is that most a/c with fuel dump will do so from the center (centre) tank only, like the 767-300, and getting rid of all this will not reduce your weight to MLW in most cases anyway! Bit of a pointless exercise IMO.

Remember also that dumping fuel, even when desireable, might well be prohibited, due to turbulence, thunderstorms, or any fire (engine, cargo hold...). If you were on fire of course, and want to dump fuel before landing to reduce to MLW, you need your head examined.
I used to love the smell of Jet-A in the morning...
 
SlamClick
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RE: Is It That Necessary To Dump Fuel?

Tue Oct 19, 2004 12:05 am

It's been my experience that dumping fuel is a very rare event. I've only seen it being done twice, once in an emergency and once because of bad planning, by a Korean 747. (Over the Sisquoc Condor Sanctuary - I ratted them out.) They arrived Seoul-LAX with too much fuel and were dumping during the descent. Incredible.

Dumping from a center tank only might make a huge difference in an overweight landing. The fuel between the mains is considered (for structural purposes only) to be part of the zero-fuel weight. It is that fuel I'd be most anxious to be rid of.

The issue in dumping to weight is really to permit a rejected landing or missed approach, and not so much in reducing the actual touchdown weight to save yourself ten bucks on the overweight landing inspection.

If a heavy four-holer shells an engine right after liftoff and they decide that landing soon is a good idea, they may dump fuel. If the captain says: "the hell with dumping, I can land this thing right up to MGTOW." he is exercising his judgement. If he returns to land, heavy, a fire truck rolls out on the runway ahead of him and he must reject the landing - which he then is not able to do, and he either rolls in on one wing or centerpunches the fire truck it is a PILOT ERROR crash. He used bad judgement in returning to land at too great a weight to permit a rejected landing.

If he holds a US FAA license and has the bad manners to survive the crash, it will probably be revoked.

A controlling principle in airliner performance is that we cannot load a plane and then operate it into a corner where we need all our available power to get it out. It is not expressed in those words, but read part 25 to see how accelerate-stop and accelerate-go numbers are derived and you will see what I mean.
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asteriskceo
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RE: Is It That Necessary To Dump Fuel?

Tue Oct 19, 2004 12:58 am

A Mesa Airlines pilot told me that they had to return to Las Vegas due to a weird banging sound on the outside of the airplane (which they couldn't see). The CRJ doesn't have a fuel dump system, and they had to make the decision of going on to Spokane, or turning around. They said they made the decision to turn around, but they would have had to circled around the airport forever to burn the fuel, and the banging sound was getting worst. They decided to land, and the manual says to land as soft as possible. So they executed a soft landed. Everything was fine. Turns out that the ground crew had left the extension cord (where they plug in the headsets to the aircraft to talk with the pilots) plugged in to the side of the plane. The cord had whipped so violently in flight that it made a dent in the side of the plane, if they would have continued, it would have done serious damage to the CRJ.
 
miamiair
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RE: Is It That Necessary To Dump Fuel?

Tue Oct 19, 2004 2:40 am

It is all about judgement. If I am flying between poin A and B, and halfway there I have smoke in the cabin, bet your bippy I'll be coming out of the sky like a ruptured duck and get it on the ground. Remember, a good landing is one you walk away from, and exceptional landing is when you can re-use the airplane afterwards.

All kidding aside, to me, my greatest concern is fire/smoke in the cabin during cruise. I have two examples to serve me well, ValuJet 592 and Swiss Air 111. Dumping fuel is secondary as opposed to getting the airplane down as safe as possible.
Molon Labe - Proud member of SMASH
 
SlamClick
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RE: Is It That Necessary To Dump Fuel?

Tue Oct 19, 2004 6:52 am

Won't mention any names but a 727 freighter got cargo smoke just a few years ago and the crew stayed airborne long enough to run the entire checklist, about thirty extra minutes. The company modified the checklist to state

LAND AS SOON AS POSSIBLE


before it started into solving the problem.

Pretty amazing that you could, on random selection, get three guys up front all at the same time, none of whom understood that basic fact - you let the airport fire department deal with fires!

Edit: Just to make it as clear as I can to you newer pilots.
Airplane on fire = BAD THING.



[Edited 2004-10-18 23:53:54]
Happiness is not seeing another trite Ste. Maarten photo all week long.
 
Yikes!
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RE: Is It That Necessary To Dump Fuel?

Tue Oct 19, 2004 8:15 am

Ditto.

Swissair at Halifax.

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gigneil
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RE: Is It That Necessary To Dump Fuel?

Tue Oct 19, 2004 11:06 am

This was well discussed a few weeks ago... more information there

http://www.airliners.net/discussions/tech_ops/read.main/100125/

N
 
ZKSUJ
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RE: Is It That Necessary To Dump Fuel?

Tue Oct 19, 2004 4:46 pm

A SQ 744 had a tail strike at AKL last year. IT made it back to AKL safely without dumping fuel. The flight from AKL-SIN is about 10.5 hours so it is possible to land safely with a full aircraft without dumping fuel.

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