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Thread: Prop fell off!!

  1. #11
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    Default Re: Prop fell off!!

    Just looked at it again - I am wrong on the 11:38 part. Pressing to put the keepers in does not press the shaft to the bearing. But I know the shaft has to be sufficiently tight to the bearing to prevent if from spinning in the bearing. Possible it all gets tightened (pressed) when the halves are assembled and the front an back bearings are both "squeezeed" to the shaft when the housing is torqued.

    Greg

  2. #12
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    Default Re: Prop fell off!!

    I'm sure it is a snug fit between the bearing and the shaft, but not a pressed on fit. He does press the shaft out, but says he taps it in. I think he just used the press rather than pounding on it. Still wondering why the prop was freewheeling on the airplane in question in this post. JImChuk

  3. #13

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    Torrington, wy
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    Default Re: Prop fell off!!

    Quote Originally Posted by avidflyer View Post
    I'm sure it is a snug fit between the bearing and the shaft, but not a pressed on fit. He does press the shaft out, but says he taps it in. I think he just used the press rather than pounding on it. Still wondering why the prop was freewheeling on the airplane in question in this post. JImChuk
    Disclaimer-Just a dumb mechanic here who works on semis & has never looked inside a b-box other than the video posted and recommends having a professional make your final evaluation.

    It looks like to me if the split washers came out, for whatever reason, you would get exactly what the original poster has described. From what I see the propeller shaft is driven by what I believe the youtuber described as a dog gear, the dog gear is driven by the large gear that slides on the propeller shaft. So if the split washers fail the dog gear & large gear can decouple allowing free spin, and also allow the propeller shaft to be pulled out of the front of the gear housing. I also think this failure could likely show little to no other damage other than dislodged or broken split washers, also mentioned by the original poster. A close inspection of the parts should reveal the cause of failure though. Now, without going into any details, that b-box looks like a terrible design to me and I can’t believe they sold it for aircraft use.

  4. #14
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    Default Re: Prop fell off!!

    Now I'm wondering if I can't read and remember any thing or what. I never got that the prop came out in the original post, or did the post get edited and I never went back and reread it? Reading the first post now, I would say 72cheavy is right in his comment of what caused the problem. As far as those keepers go, that's pretty much the same design that hold valves in place on every 4 stroke engine. The guy I mentioned in my first reply that had his prop fly right off the plane, had a prop strike before this and never inspected anything before he ran up the engine. Is there more to the story? JImChuk

  5. #15
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    Default Re: Prop fell off!!

    Well, I guess we all agree as that is exactly what I said yesterday morning in post #10! I guess we'll have to wait for Bluebird to confirm/deny.

    Greg

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