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Helicopters - Dumping Fuel

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Helicopters - Dumping Fuel

Old 1st Dec 2013, 07:05
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Helicopters - Dumping Fuel

1. Can helicopters dump fuel, even small ones?

2. If they can, in what circumstances would they do so?

I did not think that weight reduction was a factor in helicopter operations.

Thanks in advance
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Old 1st Dec 2013, 07:49
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Not many have the capability that I know of but they do exist.
The French Navy Alouette 11's I saw at Frejus Naval base in the Var region of France in 1988 had the capability.
An example for use - if you were searching for survivors and found them before you had burned off much fuel you could dump fuel to allow you to hoist the survivors aboard.

Alouette II

Only other helicopter I ever saw that could dump fuel was a Court helicopters S-61 in Cape Town SA. which had a belly mounted aux tank that could be jettisoned completely.
Example of use - coming off an offshore helideck - lose a stove - one click - you are 1500 lbs + lighter ( I don't remember the combined numbers for weight of tank and fuel) but it was a big tank and you would be in a much better position to fly away VS ditching the beast in the cold South Atlantic.
As I recall they used to use it to do crew changes on ships transiting around the Cape of Good Hope and they were sometimes a long way offshore.

Only two I ever saw but there must be more.

I am sure someone will be along shortly with better information.

You would probably get better results posting this question on the rotorheads thread.

Last edited by albatross; 1st Dec 2013 at 07:55. Reason: suggestion.
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Old 1st Dec 2013, 08:08
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Military helicopters sometimes need to reduce weight. For example, to pick up an under slung load or to carry extra troops who might need moving in a big hurry. Certainly the Puma HC1 had a fuel jettison system. One of the few times I was tasked to use it was over the jungle to deal with a certain illegal crop. It wasn't normally used because the aircraft was short of fuel even with full tanks.
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Old 1st Dec 2013, 09:03
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Sea King has a fuel jettison system. Routinely used on SAR Ops in situations where there just wan't enough power available (mountain downdraughts etc).
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Old 1st Dec 2013, 09:32
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Very few machines have a fuel jettison capability, and almost all of them are military in origin. I'm discounting the jettisoning of external tanks, more the plumbing to an external pipe.

As SS says the Sea King has a fuel jettison via a pipe above the tailwheel, which in the original HAS1 (ASW) machine was a smallish diameter with a low flow rate. It was, however, about the same diameter as the arrestor hook on the Bucc. Cue a wind up when Bucc driver chum casually asked what the pipe was for when we were mid Atlantic flying non diversion ops from Eagle.

"That's the mount for our hook when non diversion flying in case we have to make a single engine running landing"

It took 4 hours before the unrelated Sea Vixen drivers were asking when we would be fitting our hooks
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Old 1st Dec 2013, 09:34
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Aerospat' AS365N1/N2 Dauphin (or at least some versions of) have a fuel dump system. To enable Class A Perf take-off from confined areas/elevated helidecks.
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Old 2nd Dec 2013, 10:55
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Seahawks have a fuel dump as well.....good for reducing weight for say, an oei recovery to a smaller deck ( say a frigate or something).

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Old 3rd Dec 2013, 19:51
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Merlin + EC725

Military EH101 has fuel dump (but I think it melts some glue or something). I think the French have a Super Puma which dumps an internal aux fuel tank overboard on a button push.

However, just love the comment that weight reduction wasn't a factor in helicopter operations...probably not if you're just flying rubber dog doo from a to b...but for doing anything useful its great....just pray your master dump shuts when you tell it to.
Old 3rd Dec 2013, 20:36
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Wessex used to have a fuel dump ability. It was possible to do a running take off at 14000lbs (normal hover Take off limit 13600lbs) so it gave you the ability to reduce weight to make landing safe particularly after losing and engine.
I only ever was on a flight once where we had to dump fuel prior to being re-tasked to lift a heavy under-slung load just after we had refuelled. To give us out of ground effect performance.
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Old 5th Dec 2013, 06:14
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The S61N was operated with a jettison facility on the North Sea for offshore support, I never flew it but I seem to recollect that it was to improve the en-route performance (or at lease operate as a way Group A En-Route would not be limiting). I could be completely out of the park for the reasons, but I suggest posting this on rotor heads may get a broader (and probably more correct) response!
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Old 5th Dec 2013, 11:47
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Bo105 has fuel dump capabilities too.
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Old 20th Dec 2013, 04:23
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In addition to the 'Normal' phase of operations, the fuel dump system would help a great deal to offload in case of OEI conditions for multi engined helicopters/emergencies where lesser all up mass would facilitate safe conditions.

However, I feel that carriage of additional load or troops is part of flight planning and fuel dumping operations as an alternative to poor planning won't be accepted in most cases.
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Old 20th Dec 2013, 11:14
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Mmmmm ....

As Dagw00d pointed out ... the Bo105 had a dump system that allowed for all the fuel to be dumped from the 'main' tanks which left only what was still in the supply tanks at the time of the dump ... IIRC it dumped at a rate of 50-100kg/min (or something like that??) ....

I believe the same dump kit components 'could' be fitted to the BK117... but I don't think it was ever certified for use on that airframe.
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Old 20th Dec 2013, 11:28
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The S-61N I flew on the North Sea never had a fuel dump facility. However 1 aircraft (G-ATBJ) operated offshore in India from Juhu, was fitted with dumping from the centre tank to allow a reasonable payload to be carried in the high temps experienced there.
For the same reason all the anti-ice equipment was removed, including the heated windscreens, which became a problem in the monsoon when the screens misted up!
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Old 20th Dec 2013, 11:55
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Only once, from a Wessex in NI in order to reduce weight for something, but cant remember what! Did the dumping over the sea.

Not permitted from a Puma if the IRJ was on, cant think why....
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Old 20th Dec 2013, 14:11
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All of the Bristow S-61Ns had fuel dump fitted to the centre tank (1500 lbs I think)

Some CHC EC225s have fuel dump for flights out of Dili to the south. The 332L1 used in Dili also had dump fitted.
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Old 20th Dec 2013, 15:19
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The fuel dump pipes on the S-61N.

EI-SAR has its pipe under the central fuselage.

EI-CNL has its fuel dump pipe on the rear end of the fuselage.

500 Fan.
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Old 20th Dec 2013, 16:16
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The PZL Sokol have it too but only in engine failure cases (according to manual).
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Old 20th Dec 2013, 22:07
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Australian Black Hawks were fitted with the Sea Hawk dump system permitting 850lbs a minute dump rate or so. Helps with drift downs and OEI situations plus enables weight shedding for operational reasons as mentioned by several above.
It is in the checklist to consider after an OEI event.
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Old 20th Dec 2013, 23:09
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Most Helicopters with Aux Fuel Tanks have that capability....if you leave the Transfer Pump on too long and vent the Aux fuel over the side after topping off the main tanks.
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