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Airframes & engines after this enforced layup, sugestions?

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  • Airframes & engines after this enforced layup, sugestions?

    Just a thought, cos that's all most of us can do due to the present situation. Our aircraft are presently laying untended and unused for a, possibly, extended unplanned period. Based on the experiances of this group what should we check before springing into the air when purdah is lifted. I have a few ideas but a dicussion based on the experiances of a number of people would be useful

  • #2
    I'll start the list with:
    Airframe corrosion - especially in any moisture trap areas and where dissimilar metals are in contact.
    Rodent damage - have the mice been at your wiring or air filter?
    Fuel degradation - drain fuel (and water!) from the tank and replace with new. Keep the old fuel for the mower.
    Engine internal corrosion - depending on your engine type, it is likely that at least one cylinder has a valve open and can collect moisture from the air, especially around this time of year.
    Oil contamination (4 strokes) - crack open the drain plug and check the oil in the bottom of the sump for water.
    Battery degradation - fully charge and check condition with a battery tester.
    Tyres pressures

    Next please....
    Pete T.

    "A closed mouth gathers no feet".

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    • #3
      Yup, that's a good start, remember that disimilar metals include bolts through alloy or stainless componants.
      It's also worth looking into voids, inside wings etc. I remember Mark of Galaxy Micro telling of checking a Thruster that had come in for permit inspection. He found a Squirrel's nest inside the wing.
      For two strokes, although the engine normally remains nice and oily inside the bores may well have drained fairly dry. Fortunatly normally fairly easy to check looking into a plug hole and a little oit induced before start up won't hurt.

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      • #4
        A couple more thoughts,
        Two strokes, when you are allowed back to the airfield but maybe not allowed to fly if you cannot start the engine turn it over a few times to move the oil about a bit and prevent any acidic buildup on the bearing serfaces.
        Four strokes, here I'm on less well known territory. I do have some experiance of Jabs, a much better engine than generaly supposed but one of two things that they notoriously dislike is not being used. Just turning the engine over is less than helpful as it wipe oil from surfaces, four strokes having far less oil about. The camshaft can suffer badly from this.
        The open valve can cause at least two problems, corrosion in the bore and corrosion on the valve preventing it from closing fully.
        I'd suggest the first can be helped by first locating which is open by removing the rocker covers. Having located the potential problem induce a little oil and rotate the engine by hand to move it around the bore.
        Valve not fully closing. This is the one that leads problems with the valve seats and sometimes the valve itself. With the Jab being direct drive you can locate the one needing a look by rotating the engine by hand with the rocker covers off and you will feel the difference in compression and the position of the valve gear will tell which cylinder it is. Then as a final check after the engine has been run for a bit check your tappit clearances, a potential problem will show as a tight tappit.

        Have anyone any ideas about 912s

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        • #5
          Might be worth those with Jab engines giving the cylinders a bit of an oiling as they are plain liners with no plating, a spray of acf50 though the plug ole should do it, just remember if you are using a bent straw to direct the oil that you keep hold of the straw as it might fly off and dissapear down the ole (don't ask)

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          • #6
            Yup, that sounds good to me. Do you think that after a layup it might be worth a oil change with the possibility, or even probability, of a build up of condensation in the sump. To much of that could, in the worse case, give enough emulsion in the filter to clog it to a degree. Do you folks think that a possibility?

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            • #7
              Has to be worth doing Ginge, I actually overfilled my jab engine with an extra 2 quarts in the hope that it would immerse the camshaft, it being a taildragger I imagine the front half would be left high and dry otherwise, I'll be draining it before startup of course
              I'm hoping that I'm being overly pessimistic about the length of layup.

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              • #8
                I think we are all hoping that it will not be a long as we fear, but wise precautions have got to be worthwhile.

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                • #9
                  Dare I say it, but the LAA have issued a pretty comprehensive Technical Leaflet on the subject. Are the BMAA considering anything similar?

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                  • #10
                    There's a big difference between the LAA fleet of mostly CofA aircraft and the BMAA fleet of PTF aircraft. CofA aircraft are subject to rigorous manitenance requirements, involving specialised individuals who may not be able to attend to aircraft under the current restrictions. As such, it is the responsibility of the LAA to issue such guidance when their normal prescribed procedures are restricted.

                    It is one of the big advantages of microlight flying that we are trusted to carry out our own maintenance at our own discretion.

                    I agree that an advisory guide from the BMAA would be welcome.
                    Perhaps in starting this thread, Ginge has begun the process of creating that guide.
                    Pete T.

                    "A closed mouth gathers no feet".

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                    • #11
                      I'd missed that thanks.

                      Yes there is some good stuff in there particularly about cable maitenance. Also about fuel filters, I'd not thought about that.

                      A pity there is nothing about the 912 family of engines or Jabirus as none of the 4 strokes do as well as 2 strokes in this kind of situation (far less oil about). it is all very well assuming the engines are inhibited but this was sprung upon us and I wonder how many are readied for a layup.

                      It is well worth a read though, and is available to be read by all on the LAA website

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