Helicopters - Dumping Fuel
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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.
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.
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.
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.
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.
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.
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!
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.
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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
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
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........
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........
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Fuel dumping
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.
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.
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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.
....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.
Whirlwind 10 Fuel Jettison
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.
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.
....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.
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.
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.
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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 
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"
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"
Last edited by ericferret; 22nd Dec 2013 at 11:54.
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.
You could dump from the centre tank down to 150lbs, if my memory serves me correctly.
