vacuum problem

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  • #83727

    On shutdown yesterday, left engine first, the “Red Pin’ on the left side did not pop out, vacuum with right engine running in the green arc, next flight, reversed shut down, right engine first, right pin projecting as normal, left vacuum in the green arc, on shuting down left engine the left pin failed to pop into view again. Where do we start looking for the problem? any other tips/ sugestions welcome! Need to fly IFR next week, so dont want to go with this snag.

    #95729
    quote RLORETTO:

    On shutdown yesterday, left engine first, the “Red Pin’ on the left side did not pop out, vacuum with right engine running in the green arc, next flight, reversed shut down, right engine first, right pin projecting as normal, left vacuum in the green arc, on shuting down left engine the left pin failed to pop into view again. Where do we start looking for the problem? any other tips/ sugestions welcome! Need to fly IFR next week, so dont want to go with this snag.

    I haven’t solved my “Vacuum Issues” problem yet. See earlier thread. I’m getting normal vacuum indications now, but my de-ice boots still won’t run on the right engine. We’ve tried a different de-ice shuttle valve on the right side with no change. Interesting search for a used valve, BTW, price range $400 – $4800.

    I think my vacuum indication problem was caused by a badly heat-damaged vacuum hose — it runs in close proximity to the turbo, from the de-ice shuttle valve to the vacuum line into the vacuum pump. On initial inspection, the hose showed some cracks then broke apart during removal. It was probably leaking to some extent.

    I’d look closely at all the vacuum hoses/lines and fittings in the engine compartments first. If your boots are operating normally, on each engine, your problem could be the vacuum manifold valve, as Eric suggested in my earlier thread. Or you could have a faulty vacuum gage.

    Next step, for me, will be a cleaning of the de-ice oil separator and filter on the right side. If that doesn’t fix it, I’m down to the right side de-ice control valve…

    #95730

    Thanks, no, the boots work OK, {did not use them on this flight, but they have been faultless this Winter} We intend to go into the whole system on Monday, will re check boot opperation then, any guidence to expedite trouble shooting is welcome, Its seems that both vacuum pumps are doing their job OK, but dont want to fly in our weather with the Vacuum system failure warning U/S, Again, any help is most welcome!

    #95731

    I’d make sure the boots work OK on each engine, on the ground, with the opposite engine shut down. 1500-1700 RPM should be sufficient to operate a boot cycle on one engine with no adverse vacuum indication. At least that’s how mine work on the left engine 🙂

    Good luck, let us know what you find.

    #95740

    Fixed! Ran the aircraft and cycled boots with both running, then shut down left side, all indications normall, including “Red Dot”, repeated with Right shut down, Left running, all indications again normall, both vacuum pumps in green and all instruments / boots normall, must have simply been a stuck “Red Dot”, maybe due caused by flying in very heavy rain for an hour, then descending into very cold temps . It may all have been for naught, heavy ice forcast for the morning from surface to 8,000ft!.

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