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Thread: Prop Balance

  1. #31

    Join Date
    Jun 2013
    Location
    Spokane, Wa
    Posts
    120

    Default Re: Prop Balance

    mine is 4152298, and Larry's is pretty close if I remember correctly.

  2. #32
    Senior Member
    Join Date
    Jul 2013
    Location
    Highlands Ranch, CO
    Posts
    404

    Default Re: Prop Balance

    Okay guys, You've both got me pretty frustrated, so I'm going to tell you why and leave it alone from here on out. Please bear with me until the end and then do what you want.

    These forums/threads are for us to help each other out. Scott, this is the 2nd thread you've started supposedly attempting to find and fix your vibration issue. Apparently that also includes it fitting into some cost/risk/reward formula. Sometimes when it comes to safe and proper operation - that formula might not be the best choice, particularly if you invite others into your aircraft. You can choose to nickel and dime it, you can choose to take risk, you can choose to attempt to find and fix the problem or not. Heck, that's why we all choose to run un-certificated, experimental in the 1st place.

    But as a reminder, others (passengers) may not have your same view. So here's why I'm frustrated as you've asked for assistance and some have spent considerable time attempting to help and it seems you guys just don't get it!

    #1: Scott, you've stated you and Larry are both getting the same information from Rotax. You are not!

    If Larry's statements are correct, you would have been told you needed to replace your dog gear and gear set - you weren't told that.

    You were not even given the choice as you've alluded to. In fact, you were not even told there was any spalling at all, so you didn't even have a choice to make. Or the spalling information to even make an informed decision.

    So I don't see how you can state you are getting the same story.

    #2: Larry, you stated: "I have checked runout of the prop flange, prop shaft and crank gear. These are all fine. I'm sure Scott's is too." and further stated "I appreciate the out of the box thinking".

    As if my suggestions are not ordinary and inferring that Scott doesn't need to check his.

    Scott has no way of knowing that unless they are checked and correct. So you can't eliminate them as a possible cause unless and until they are checked.

    Further, these checks are not out of the box, off the wall ideas I've simply thrown out there. They are REQUIRED checks by Rotax whenever the gearbox is removed, inspected and reinstalled!

    Please refer to the Rotax 912 Heavy manual chapter 72, page 39. Checking the propeller hub (flange) for runout is the 1st thing to be checked - it's not a suggestion.

    Refer to the chapter 72 page 53. Checking the crankshaft for runout is not a suggestion.

    Refer to chapter 72 page 54. Checking the prop hub for true (radial gear backlash) is not a suggestion.

    So, before you guys jump all over me - I do realize that in a way anything Rotax says are really just optional suggestions, as you are running un-certificated, experimental aircraft and that allows you to make whatever choices you want. But those items are there for a reason and should be checked.

    Do what you want to - that's why we choose to be in the experimental category, but do me a favor: If you choose not follow this or any other manufacturers "suggestions" for the proper and safe operation of your aircraft - please don't invite anyone else to participate with you - either in a forum or in your passenger seat - their tolerance for risk may not be the same as yours!

    Thanks for listening, I'm done with this issue, I'm sure you'll follow up with the responses to this post and maybe the eventual solution to your issues.

    Good Luck,
    Greg
    Last edited by Danzer1; 10-17-2013 at 05:08 PM.

  3. #33

    Join Date
    Jun 2013
    Location
    Spokane, Wa
    Posts
    120

    Default Re: Prop Balance

    I am going to try to answer this as politically correct as I can, however it really fries my a$$ when someone who doesn't know me at all assumes from one or two posts he does.

    First of all- Jim Scott from Aircore came out and worked on my plane on Saturday. Doublechecked everything I had done, looked everything over for himself, and came to the conclusion the dog gear is bad. Told me it is not a normal failure, and normally reshimming the gearcase takes care of any vibration/chatter issue. Then I pulled my gearcase apart, checked the runout on the propshaft(perfect), prop flange(perfect), crank(perfect), looked at all the gears and bearings and did not find anything abnormal. I did not get a chance to press the dog gear out of the case yet but when I do I will shoot photos of my dog gear and post it up. I then called CPS and spent $1300 on the gearset(backordered) and dog gear.

    I am not going to comment on anything else.

  4. #34
    Senior Member Slyfox's Avatar
    Join Date
    Dec 2008
    Location
    felts field, spokane
    Posts
    1,327

    Default Re: Prop Balance

    scott I hope soon you can have a decent running fox. Sunday was quit a day. I started up my fox and was in a hurry. It didn't want to start, banged and farted. I know better and kept it banging and farting. It did start, but I should have used more choke. I should have had it plugged in. It was cold. Anyway, I flew it to deer park and landed, now it's running really bad. I was joking when I said you gave me a virus. I was parked close to your fox. I went and flew back to felts with no problems. after landing it ran rough again. I made the right decision, grabed the rv and went for the flyout, which I had a great time. later that night I looked at the kitfox and found what I thought was the problem and I was right. the right carb socket was cracked open. monday I ordered the carb sockets from jbm. I recieved them yesterday and put them on last night. while putting them on I found the left cable, new style, was broken where the outer housing joins with the carb. OH man, you really got me on this one . just kidding. I fly this thing so many times a week and now I have all kinds of problems.

    anyway I connect the cable and tie it up good. now to order a new cable. John, when do you get back in the office so I can order parts.

  5. #35

    Join Date
    Feb 2013
    Location
    Helena, MT
    Posts
    3

    Default Re: Prop Balance

    Scott, I had similar symptoms on my recently acquired KF2, and couldn't perform a carb balance due to the extent of the shaking below 2500rpm. Talked to John at Kitfox and he suggested checking the motor mounts. Kitfox Service Bulletin #54 explains how to shorten the mount bushings. Took me half a day to perform the adjustment. Smoothed out my 750hr 912UL so that I can cold idle at 1000. FWIW. Woody.

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