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Look what I found in the oil screen...

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  • Look what I found in the oil screen...

    Look what I found in the oil screen...

    I did an oil change today, and as usual, I removed the oil succion screen to inspect for any debris...this is what I found.
    Not sure what it is, but it looks like remains from a ball bearing. These 2 large debris stick to a magnet.

    Seeking unbiased opinions before I call my engine shop tomorrow. Any idea what this is? Obviously, the aircraft is grounded for now

    O-540 B4B5, freshly overhauled (ONLY 60 hrs since OH)
    Engine never missed a beat...runs great.
    No large debris found at the first oil change (only two tiny slivers <.100’’ long)
    I was running on mineral oil, and was planning to switch to regular oil today...


  • #2
    Well that is part of a ball bearing separator.
    And it should not be loose in the oil sump screen.
    Magneto?, piece captured in case from prior to OH?
    cannot think of Ball Bearing in a 540 other than Mag.
    This bearing cage failure mode is rather unusual for a low time low speed bearing.


    • #3
      I think you’re right....I looked at the o-540 part catalogue, and the only ball bearing I found is from the magnetos, PN 67542. Looks like the ball retainer failed.
      I’ ll contact my engine shop tomorrow, but for sure, the magnetos will come off for inspection.
      Thanks for helping...I’ll post back when I have More info.

      Last edited by Aero_tango; 07-03-2019, 10:56 PM.


      • #4
        Now the tough questions..........
        if the mag bearings are intact then why was the object not detected at overhaul?
        And if is from your mag bearing, do you have it all?

        At least it does not appear to have been smashed or run through gear mesh.

        this type of failure is usually from fatigue of the cage from ball bearing coming out of load carrying and shooting into the retainer cage.
        or ............... severe misalignment or high vibration.....

        A bit odd for a slow speed bearing with no real radial loads.....

        Best of Luck on your sleuthing!


        • #5
          Holy crap, Michel ! That's unnerving....

          Let me know what Manu has to say about this; as you know, I had my 540 overhauled there too....


          Maule M5-235C C-GJFK
          4 Seat Bearhawk #1078 (Scratch building)
          RV-8 C-GURV (Sold)


          • #6
            That is not a "big" deal, as far as failed engine bearings go. I don't think you are talking bulk-strip...

            Obviously you need to clear the sump of bits and replace the bearing!

            That bearing can be removed, easily in some cases. Just pull the mags and you will see it, sitting in there. Be careful because parts are going to fall into the accessory case / sump.

            If you are lucky, the bearing will come out of the engine housing attached to the magneto drive shaft. That would be the best case. If you are not lucky, you will need to pry it out without losing parts into the sump. If you have bad luck, you will have to remove the accessory case to get the runner out of the engine case (press fit is not always the same fit). This means taking the engine off the ship.

            Then you just need to sweep the sump for the other "spare parts". You may need to pull the sump to be sure. But that can be done just with cowls removed.

            Unless you are a gambling man, you want your most qualified engine professional to address all the above tasks for you.

            I would be looking hard at that mag... the bearing may have put a lot of stress on the mag, or vice versa.
            Last edited by Battson; 07-04-2019, 08:37 PM.


            • #7
              Here is some update...
              After talking to my engine shop, it was decided to remove the mag and pull the mag gear out:

              Right Mag gear: OK

              Left Mag gear: Half of the bearing is gone...down in the sump
              This is what I fished out of the sump (with a magnet...)...still missing quite a few bits/pieces, specifically the outer race

              Damage to the Mag gear:


              Lycoming part list....


              Sent all the photos to my engine shop, waiting for their response...and next course of action..

              Attached Files


              • #8
                Major frowny face. Why can't this happen in January? On the plus side, at least you found it on the ground and not in the air.


                • #9
                  Bummer! No oil filter, just the screen?

                  Is the sump hard to remove on a 540?

                  I found some not awesome stuff in my filter on my first oil change. Had I not had a filter I would have torn the engine down completely. Pulling to sump to clean out the “extras” took less than an hour.
                  Scratch Built 4-place Bearhawk. Continental IO-360, 88” C203 McCauley prop.


                  • #10

                    Are you sure the outer race is not still in the bore in the case?

                    This is a there is much more to this story situation.
                    The location of the wear patterns on the gears and the extensive size of the contact patch of the mesh, and the
                    evidence of lots of sliding contact. A proper geometry
                    should NOT show contact patch from root to crest.
                    it should blossom out from pitch line. Feathering away
                    as the next tooth picks up load.

                    The mag gears are lightly loaded and I have seen mags and drive gears with thousands of hours look better than these. Sorry to say that!
                    Wrong drive gear for the mag gears or versa vice?
                    Incorrect Pitch Diameter machined into one of the sets?
                    Lack of lubrication within the accessory section?
                    Driving gear canted and wobbling?
                    Bearings / bushings worn on idlers?
                    Wrong or incorrectly machined accessory section?
                    If mag bearings are angular contact bearings were they
                    Installed backwards?
                    The inner race on the failed bearing is not fully seated
                    against the shoulder..... cause? Result?

                    Thinking that the bearing failure is the result not the cause.

                    Lots to consider here, you gotta know cause just a part change out will have a repeat of this is my guess.


                    • #11
                      I'm with '272 . Something about the gear train isn't right. If I had to guess, there's a gear, or two, that looked right, but weren't compatible. I've seen pump bearings come apart like that one, but the collateral damage is usually impressive, which is to say the bearing was the result of failure elsewhere. Hate to say it, but there's 'metal' in that engine that shouldn't be there.



                      • #12
                        This is one of those instances where...if you didn’t disassemble the running engine and inspect parts as you’d better check the gear alignment for that magneto. There are three different thickness spacers for impulse coupled magnetos.

                        Edit my last: I see the parts manual shows two different spacers....aircraft magneto service says there are three. I bought the thickest one they had, then machined/fit the magneto.
                        Last edited by Mark Moyle; 07-05-2019, 05:31 PM.


                        • #13
                          Bummer! No oil filter, just the screen?

                          Is the sump hard to remove on a 540?
                          I do have an oil filter. The screen I’m referring too is the finger screen at the bottom of the sump. All lycoming engine has this screen. It did exactly what it supposed to do...capture any sizeable debris. This screen is upstream of the oil filter.

                          Major frowny face. Why can't this happen in January? On the plus side, at least you found it on the ground and not in the air.
                          For sure...fortunately I inspect that finger screen, otherwise it would have been unnoticed until something failed catastrophically in the air.
                          I was planning to leave for OSHKOSH on July 19...I guess it would be in 2020.


                          • #14

                            Thinking that the bearing failure is the result not the cause.
                            I’m with you on an engineer, this is the primary thing I want to understand. If the root cause is not found, problem won’t disappear!!!!

                            On that point, I think I may have found the root cause. It seems that the bearing recess in the crack case (on the failed side) is oversized, when compared to the other one. I wasn’t able to measure the diameter of the recess (no access) but I used a 7/8 socket as a gauge.

                            The socket is slightly larger than the bearing as shown below.

                            This is is the view of the bearing recess in crankcase

                            this is the view of the same recess, with the socket penetrating in the recess ...the recess is much larger than the socket!!! , There was likely a sleeve in that recess.. My theory for now is that sleeve works it’s way out overtime, and then the bearing failed...the only way to find out is to drop the sump and hunt for all debris


                            All these photos were sent to my engine shop late yesterday.
                            The manager called me today and want me to send the engine back. All repair will be covered under warranty. They are puzzled too by this oversize recess. ...
                            They also offered me to send a mechanic to remove the engine from the plane. Nice gesture, but I said that I prefer taking care of the removal of the engine. They agreed. They said to call them when it’s off the plane, and they will send someone to pick it up....This is certainly good support from them.

                            Attached Files


                            • Battson
                              Battson commented
                              Editing a comment
                              That looks like welding and grinding in the case, around the recess. Not a nice job either. I assume this is an old case, like so many of them are.

                              I would be asking to see photos of the finished product after the repair, before they button the engine back up. Just to be sure the workmanship is where you need it to be, in terms of quality.

                          • #15
                            Unfortunate situation, looks like you have a handle on it with good support at this point.
                            Best of luck !