Brief RPM surge

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  • #84977
    sworley
    Participant

      The last two flights I’ve noticed at cruise an occasional RPM surge of about 50 RPM by my right engine. There is an audible change and yaw so I know it isn’t an indication issue. The surge will last a second or less and happen every 5-10 minutes.

      Only a couple of flights ago my prop governors were overhauled, so that seems a likely place to look. During the run up after the prop governors were put back in the gear on the tach generator in the right engine separated and lost some metal. My mechanic cut open the oil filter and found a couple pieces of metal on the magnet. The gears were replaced.

      Any ideas what could be going on or what the next steps should be?

      #104494
      pmcnamee
      Participant

        Sounds like a Propeller Synchronizer linkage problem. The slave is the right engine. The system has about a 50 RPM authority.

        Keep’em Flying

        Pat

        #104495
        sworley
        Participant

          I should have flown with the prop sync off for a while to check that. Thanks, Pat.

          #104503
          rwelsh
          Participant

            You can pull the governor and see if the governor oil screen has any metal; if so you have major (pun intended) problems. These governors are very old as some date to WWII and reconfigured to our engine/prop combination. I would think they messed up something in their “rebuild”. And because you have syncho, the problem may be the other side with the master trying to correct the issue.

            #104507
            sworley
            Participant

              Let’s hope that’s not the case. Today my mechanic tested some of the prop sync pins and found a couple to be out of spec.

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