Helicopters - Dumping Fuel

[A2QFI]

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

[albatross]

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 (http://www.ffaa.net/helicopters/alouette-2/alouette-2.htm)


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.

[ShyTorque]

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.

[Sven Sixtoo]

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).

[John Eacott]

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 :p

[Pontius's Copilot]

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.

[Turkeyslapper]

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).

Cheers

[GipsyMagpie]

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.

[WASALOADIE]

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.

[Thridle Op Des]

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!

[Dagw00d]

Bo105 has fuel dump capabilities too.

[peeush]

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.

[spinwing]

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.

[solitaire]

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!

[obnoxio f*ckwit]

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....

[terminus mos]

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.

[500 Fan]

The fuel dump pipes on the S-61N.

EI-SAR has its pipe under the central fuselage.
http://i306.photobucket.com/albums/nn274/Bolkow1/CHC%20Photos/P1010556_zps2ecc97e3.jpg (http://s306.photobucket.com/user/Bolkow1/media/CHC%20Photos/P1010556_zps2ecc97e3.jpg.html)

EI-CNL has its fuel dump pipe on the rear end of the fuselage.
http://i306.photobucket.com/albums/nn274/Bolkow1/CHC%20Photos/CHC%202000/CNV00070_zpsfa1b04b8.jpg (http://s306.photobucket.com/user/Bolkow1/media/CHC%20Photos/CHC%202000/CNV00070_zpsfa1b04b8.jpg.html)

500 Fan.

[corbacho]

The PZL Sokol have it too but only in engine failure cases (according to manual).

[helmet fire]

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.

[SASless]

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.:{

[Gomer Pylot]

If the helicopter is not on fire, then I don't have too much fuel. They will fly over gross, but not without fuel.

Fuel dumping for fixed-wing aircraft is only used because they can take off with more fuel than they can land with, so if there is an emergency shortly after takeoff, they may need to dump fuel to get down to landing weight. In a helicopter, if it will take off, it can land, and I ain't dumping fuel no matter what.

[AAKEE]

As SASless said: with aux fuel tanks its qiute common. The Bo105 mentioned earlier in the thread dont have dump capability as a standard feature, it comes with the internal extra tank. Im not sure, but if I remeber it right its the same for the AS332.
NH90 has it for the normal/internal tank system. Not sure if it is a extra feature, but the Swedish IOC versions have it, anyway.

[industry insider]

Fuel dumping for fixed-wing aircraft is only used because they can take off with more fuel than they can land with, so if there is an emergency shortly after takeoff, they may need to dump fuel to get down to landing weight. In a helicopter, if it will take off, it can land, and I ain't dumping fuel no matter what.

Well Gomer, if you are flying out of Dili, East Timor over 7000 foot mountains and you have an engine failure, you have 2 choices, dump fuel down to Single Engine weight or crash.

I would dump fuel. Remind me to never get into a helicopter with you as the pilot. The whole world ain't a flat swamp like Louisiana.

[Oldlae]

The Whirlwind Mk 10's of 22 SAR Sqdn were fitted with fuel jettison valves, this came in handy when we were presented with the Wilkinson Sword of Peace in the mid sixties. We had to clean the hangar floor at St Mawgan to hold the parade, a Whirlwind was moved around the empty hangar and at intervals the jettison was operated to pour avtur on the floor and we followed up with stiff brooms and wellies to clean the floor, it worked. Health and Safety, never heard of it!

[Ascend Charlie]

The BK117 A4 we bought was offered with a fuel dump system - we turned it down, because it was a one-time-use only. When operated, it fractured a frangible panel in the bottom of the tank and dropped the lot. Cost big bux to replace it, too, for a second use.

[oldgrubber]

As stated earlier the Military Seaking had a jettison system that exited by the tail wheel. It consisted of two jettison pumps that could be operated individually or at the same time, depending how fast you wanted to get rid of the fuel. As many on here know the fuel system consists of interconnected tanks, so the total “level” would go down with either the Fwd or Aft pump running and the jettison would stop when the pumps lost suction with 200lb (I think) of fuel unjettisonable in each tank. It has been a while so feel free to correct the amount. The jettison gallery runs outside the tanks down the port cabin and behind the thermal barrier out the back. We always made sure to be ready to shut off the jettison valve manually if needed during tests as it would syphon all available fuel until 200lb as stated, if it stuck open.
The Merlin on the other hand has a slightly different concept. It uses the main fuel gallery that is part of the pressure refuel system to facilitate “dumping” of fuel. This is actually quite elegant as it works on the principle that you don’t want to dump fuel at the same time as refuelling so use the same pipework and save space and weight.
There is a jettison pump in each main tank and it also uses the transfer pumps in the transfer tank to empty that one. The tanks empty to 280Kg (appx) and the transfer tank empties completely, with the fuel exiting from the underside of the left sponson.


Cheers

[lsd]

Thanks Oldlae for the reminder.......
Wessex HU5 fuel dump helped to clean up the flight deck of HMS Albion just prior to entering Mombasa in November 71.
Something to do with celebrating Taranto Night I seem to recall........

[Boslandew]

I can remember ( I think) that BAH S61's or some of them had fuel dump back in the 70's. The limitations on its use were a favourite trappers question. The only one I can remember was "Do not transmit on HF while dumping"

The only time I came close to using it was on one occasion I was en route to an unlimited deck so was planning to land at 20500 (or whatever the WAT figure for the day was) and was asked to divert to a limited deck rig that was en route, max landing weight limited to 19000lbs, for a casevac and back to shore.

[spinwing]

Mmmmmm ...

....The Bo105 mentioned earlier in the thread dont have dump capability as a standard feature, it comes with the internal extra tank ...

... sorry ol' chap but that is incorrect ... go find the option supplements manual of the flight manual and all will be revealed !!

IIRC the internal (2x 200l slipper tanks) do not connect to fuel dump they flow into the main tank and only from there can the contents can be dumped.

:E

[Oldsarbouy]

Whilst at CFS(H) Valley in the 70's we were tasked to do a role demo at Clacton on a Sunday. That must be the furthest away from Valley so a refuel was required but the only place nearby available on the Saturday was Woodbridge. A phone call to the USAF base gave us permission as long as we would put our Whirlwind in the static display for their families day. Having arrived at Woodbridge I spent an hour dribbling fuel into our trusty steed and, having made sure it was presentable for the next day we retired to a local hostelry. Next morning we were enjoying a leisurely breakfast at the all ranks mess when two USAF policemen rushed in asking if the yellow helicopter was ours. Yes, we replied thinking they had been admiring our shiny yellow machine. Well you guys had better come quick as someone has pulled the dump switch and the Base Commander isn't too impressed. Off we went to find the Whirlwind in the centre of an immaculate static display sitting in the biggest pool of aviation fuel one could imagine. Yes someone had operated the jettison switch and because we hadn't thought to disconnect the battery it had worked as advertised. Red faces all round especially when we spied the crew of a Dominie next door enjoying the spectacle and anticipating tales they could tell on return to Finningley, the home of RAF SAR.
:O

[AAKEE]

Mmmmmm ...

....The Bo105 mentioned earlier in the thread dont have dump capability as a standard feature, it comes with the internal extra tank ...

... sorry ol' chap but that is incorrect ... go find the option supplements manual of the flight manual and all will be revealed !!

IIRC the internal (2x 200l slipper tanks) do not connect to fuel dump they flow into the main tank and only from there can the contents can be dumped.


At least the ones I flew for more then ten years didnt have fuel dump (CB-3),But in documentation it was mentioned togheter with aux fuel tank . :-)

http://s21.postimg.org/n6j43vn1z/bo105.jpg

[Al-bert]

Dumped fuel many times on SAR Wessex, prior to op winching in the mountains. Especially in Snowdonia, where a ten minute transit from Valley meant we might be too heavy following our swift arrival on scene.

[Fareastdriver]

The old S61s on the North Sea had fuel jettison to improve their payload against Group 'A' performance. They could take off overweight but if an engine went walkabout they could jettison down to en-route performance weight. This was extremly unlikely to happen in the first 30 mins of flight and after that you were OK so you could plan to carry more.

[soggyboxers]

Fuel dump was pretty common in the old days. We had it on 58Ts in the North Sea on Bo105s I flew for BCalH and our Aero Contractors Dauphins in Nigeria. I remember one pilot in Nigeria who had overfilled his tanks offshore deciding to dump a small amount of fuel on the rig deck. However the jettison valve stuck open and several hundred litres were dumped. The deck was blocked for some hours and the pilot's red face on return was nothing to do with sunburn :}

[ericferret]

Amazing how fast a 365 dumped fuel in the hangar when our greenie on being asked to switch on the boost pumps had a senior moment and hit the dump switches.
How we laughed after spending an hour or so cleaning up the mess.

On the subject of fuel spills I was having a coffee with the KLM station engineer in Dar Es Salaam looking for a spot of sympathy having managed to dump the contents of a 105 main tank on the hangar floor. Not the dump system this time but another senior moment nevertheless.

"Thats just a puddle" was the response, "I had a boost pump gate stick open on a 747 in Lagos and lost 5 tonnes, try shoving the pump back in against that weight of fuel"

[Back door]

Canadian ch-124 dumps fuel at a rate of 600lbs per minute, so you really want to make sure you really want to do it.

[Attila]

Fareastdriver, Yes, we used to carry the "excess" fuel in the centre tank of the S61 until we were at the correct enroute weight and then we would transfer it to the forward and aft tanks.

You could dump from the centre tank down to 150lbs, if my memory serves me correctly.