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  • CTSW FUEL TANKS

    Recently I had to fly a very low houred CTSW so assumed everything would be 'hunky dory' (which it actually was) but was a little concerned about fuel flow in flight:

    To explain..... I had a flightplanned route of 3hrs so assumed it was prudent to have at least 80 litres onboard, according to the CTSW Fuel dipstick there was 20litres per side (which related to site glass in wing roots) so 40 more litres were required.... being extra prudent I asked for 60 litres to be placed 30 litres in each tank to give me 50 litres a side.

    Now after having added an extra 60 litres I was surprised to see that the combination of both tanks registered as 115 litres !!! still I will work on 100litres I thought..... now with a Dynon D180 telling me we were averaging in the region of 17.5 lph I estimated that my leg from Sittles to the Coastline of Dublin would use 35 litres and that both tanks will have at least 32.5 litres per side remaining :-)

    At the 'Liffy' waypoint I noticed that the RH Tank was showing absolutely nothing in it, but sometimes bubbles would appear briefly in the sight tube with a smattering of fuel ( Liffy to coast is 22nm) so this tended to concern me as I hadn't expected to see what perceived to be a basically dry tank on the RH side and a Totally FULL Tank on the LH side !!

    All kinds of calculated thoughts ranging from 'was the LH Tanks pipes blocked' to 'was I actually going to run out of gas ?' shot through my head... I wasn't even able to comprehend that even if I did only have the RH tank supplying fuel how 50 litres would have disappeared in the time I had calculated 35litres to the coastline and should have used 32litres by 'Liffy' BELLS WERE RINGING !!!

    Strangely as I got over the coastline near Dublin the RH tank seemed to be showing 15 litres again !!! still I couldn't understand why two interlinked tanks could have such an imbalance between them ? I had decided to divert into Dowth Hall to check the fuel status, but on arrival over the Boyne Bridge....found Dowth lying under a bank of cloud at about 250ft. The options were divert into DUBLIN AIRPORT or continue onward to my destination of Tandragee.... Tandragee won the toss and surprisingly even after landing there I found we had 50 litres remaining (avg 16.67lph) for the 3hr flight completed.

    I know there is some strange anomaly with CTSW tanks, but can anyone advise if there is a cure to this issue or what actually causes the fuel to drop quicker from one tank than the other ?

    :idea:

    MTIA, Peter

  • #2
    CTSW FUEL TANKS

    Flying CTSW/CT2K out of balance will drain one tank into the other which is not good if tanks are filled to maximum as it will come out of breather i would prefer the old system of switchable tanks but that's not an option ,it caused me some concern on a trip back from France when one tank emptied but as yours mine still had more than 50lts on landing ... there has been one that i know of that had full tanks on park up in the hangar ..had a flat tyre over night and emptied 1/2 tank of fuel onto the floor :freaked: bloody expensive mistake but could have been worse if it caught fire ..you need to make sure you park them level at fly-ins

    Only cure in flight is fly with empty wing down or out of balance the opposite way for a while which will drain fuel back into empty wing ..i have been told that it will not stop with fuel in this condition but it does make you think when over the sea :smilewinkgrin:

    Cheers Mike

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    • #3
      CTSW FUEL TANKS

      Thanks :smilewinkgrin: that is what I thought !!! all turns were lefthand so did spend quite a lot of time with RH Wing higher....seemed to recall something like that was the case but wasn't sure.

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      • #4
        CTSW FUEL TANKS

        Perhaps some training would rectify the situation Peter? - if you turn in balance the fuel will not slide down from one wing to another.....

        A proper microlight instructor can help you GA types to undersatnd that those pedal things are not just used for taxiing.

        paul

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        • #5
          CTSW FUEL TANKS

          [quote=Paul Dewhurst]
          Perhaps some training would rectify the situation Peter? - if you turn in balance the fuel will not slide down from one wing to another.....

          A proper microlight instructor can help you GA types to undersatnd that those pedal things are not just used for taxiing.

          paul Peter answers Paul (Jokingly).... probably more so than any instructor :nono: However if you can point me in the direction of a proper microlight instructor I will surely go and let him/her show me the correct way to turn in balance, trouble is, it is hard to teach someone who is 99.9% perfect in their flying skills :lol:

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          • #6
            CTSW FUEL TANKS

            I couldnt resist it Peter - it was such a delicious open target!

            You can tell a proper microlight instructor - they work from (and mostly live in too) caravans built in the 50's, with no wheels left and green mould on the outside and damp orange seats on the inside, and wear dirty jeans with holes in the knees, have permanent dirt under their fingernails, and drive 15year old Ford Sierra's. Usually they had big business or high power city jobs before throwing it all in for this sporting life. Unlike the majority of 'stepford' GA instructors they dont possess a GA square black flying case, and dont buy shiny black shoes and pressed black trousers and white shirts with epaulettes from Transair. If they do own a sheepskin Irvin flying jacket and green flying suit with wings, it is only becasue of a strong sense of self deprecation and piss taking!

            Ina Hogg once said that the true definition of a microlight was one with wires, open cockpit (or at least lots of draughts and rattles), capable of sustaining flight but not a living..!

            Perhaps shows that Eurostars, CT's and C42's used a school planes in lots of schools now means that 'proper' microlighting, and 'proper microlight instructors are harder to find these days...(or perhaps the cost of thse machines means they can only afford the old clothes and caravans???)

            Paul

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            • #7
              CTSW FUEL TANKS

              Yes I suppose I left myself wide open to that attack but I would much rather ask the question than find out 20nm out at sea that the tank will run dry and air lock the pipe (which I now know doesn't happen)

              The CTSW fuel sight tubes are in my opinion a bad set up for what is otherwise a fantastic aircraft, from my RH seat position I couldn't visually see the RH fuel line but could see the LH tube perfectly visible... it was only that we had flown 2hrs and seemingly the LH tank looked still full that I leaned forward to visibly check the RH sight tube and saw the evident lack of fuel showing :skull: Surely for such a high class microlight it would be a nice touch to have visible gauges on the dash ?

              OK the Dynon D180 does have fuel flow and accumulative fuel meters, but the lack of visible fuel does twitch the sphincter slightly :shocked:

              I feel that the day I fail to worry about such things will be the day that I realise that my survival instinct has been exceeded by my desire to become 'dangermouse' I think the 'yellow streak' down my back widens with every flight and therefore Dangermouse will never be a title I wear.

              [/i] :nono:

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              • #8
                CTSW FUEL TANKS

                [quote=Peter Kelsey (Ferryair) Earthrounders 2910]

                ...but the lack of visible fuel does twitch the sphincter slightly :shocked:

                Welcome to my world Peter!
                If a lack of visible fuel makes you a little nervous, you should try flying a 22 year old Shadow with no sight tubes and the most inaccurate electrical fuel gauging system known to man :rofl:
                To be honest, I work off time elapsed and allow a substantial margin for safety. This does mean that I'm unwilling to push it near to the ragged edge though (which is probably a good thing I guess).

                Comment


                • #9
                  CTSW FUEL TANKS

                  Gary Taylor BMAA 1325 wrote:

                  Welcome to my world Peter!

                  If a lack of visible fuel makes you a little nervous, you should try flying a 22 year old Shadow with no sight tubes and the most inaccurate electrical fuel gauging system known to man :rofl:
                  To be honest, I work off time elapsed and allow a substantial margin for safety. This does mean that I'm unwilling to push it near to the ragged edge though (which is probably a good thing I guess).

                  Peter answers...... the sphincter said " Lets land and check"

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                  • #10
                    CTSW FUEL TANKS

                    Just had a lovely flight Bourn to Fenland and back, about half an hour each way, including chatting to a balloonist. I only have a few hours on the CTSW since differences training from a Thruster 582, hence had to learn left hand stick and right hand throttle etc, not to mention how much more sensitive elevator and ailerons are.

                    My worry is that back at Bourn I found uneven fuel drain. Measured all levels with the dipstick in the filler hole while she was on a very smooth level hangar floor. Started with slightly more in RH tank than LH, and finished with all ~14L drained from the LH tank, which left about 7L and me a "little" uncomfortable. I noticed that with me in LH seat, no passenger, elevator trimmed, hands and feet off, at -12 flaps and 100kt she would slowly roll to the right, so I had to hold slight left aileron to keep her wings level.

                    I must say that the sight tubes are pretty useless because (obviously) they are at the inboard ends of the tanks, so you can get whatever level you want by sideslipping left or right. Slip right and the LH tank shows a higher level in the sight tube, and vice versa for the RH tank. I ended up using the inversion layer and wing tips to judge what is level.

                    Any ideas if the fault is with the plane or pilot? Chris H you examined my GST at Sandy in the thrasher so you should know!

                    See you all at FlyUK,

                    Matt.

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                    • #11
                      CTSW FUEL TANKS

                      I recently had the wings removed from my CTSW for inspection. I'd told the guys doing the work that there would be 60-70L fuel in the tanks. They called me to let me know that when they drained it, it all went into two 20L cans and they estimated about 35L. I was very surprised as I never run it this low due to the issues discussed above, so took more fuel with me when I went to collect it. As soon as I saw the level in the sight tubes I knew that the dipstick reading would be higher than 35. Sure enough, the dipstick figures indicated a total of about 62L. I knew the sight tubes were unreliable, but I thought the dipstick readings were a bit more accurate than this. Anyone else found this?
                      Sandie

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                      • #12
                        CTSW FUEL TANKS

                        We did an experiment to measure fuel flow from the gascolator on the ground, clamping the hose from each tank in return, and got plenty more than the Spec flow from each tank. I was told by an experienced CT instructor not to worry, it is well known that CTSWs drain preferentially from the LH tank and that although level in sight tubes (assuming flying in balance) may even indicated zero in the LH tank he has never known a fuel feed failure in this situation. However, I never plan to fly it with the sight tube empty and if it does get that far, just lift that (LH) wing briefly to check that there is some fuel in the sight tube!

                        Another "experienced in the CT" concurs, and says he thinks the uneven flow is caused by lower pressure over the RH wing cap/vent than the LH. He is trialling a modification to the fuel return from the carb feed tee to route it, instead of back to the gascolator, back up the screen pillar to the port tank. He's hoping that it will also reduce the incidence of fuel vapour lock in very hot weather. I experienced this vapour lock with an instructor at about 200' at full throttle, on about the 8th take off on a hot 25C day. We had a slight loss of power and misfire, remedied by closing the throttle a bit.

                        No I haven't measured the quantity of fuel by draining it. I don't use the sight tubes to estimate fuel quantity, I dipstick each tank before every flight and stick that number into the Dynon. It seems to work.

                        Roll on raising the MTOW to 600kg, which the CT was designed for!

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