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Noticeable vibration at 200+ hours 912iS Sport

in 912iS Technical Questions 9 years ago

  • Re: Noticeable vibration at 200+ hours 912iS Sport

    by » 6 years ago

    You shouldn’t have to do anything special. There can be several factors on a gearbox repair time.
    I.e. did you fly it in and they had to remove it and the prop, what was rebuilt (all the guts and new bearing and shims, etc...) or a new bow with everything already to install?
    I don’t know exactly what you’re having done, but maybe 3-4 hours. This can vary.

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell

      
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  • Re: Noticeable vibration at 200+ hours 912iS Sport

    by » 6 years ago

    I was not referring to rebuild hours - only the hours to remove it and re-install it.

    Aviation Real Estate Specialist & iRMT

      
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  • Re: Noticeable vibration at 200+ hours 912iS Sport

    by » 6 years ago

    When I had my first gearbox rebuild I was reimbursed a couple of hours labor (for removal and reinstall). The service center was also reimbursed for their full labor of servicing and repairing. Since I work on my own airplane and I don't rely on aircraft maintenance to make a living, any reimbursement was acceptable.
    When I sent my second gearbox to be rebuilt, Rotax paid for the parts and Service Center labor only. I wasn't reimbursed for my labor.
    Realistically, when a complete gearbox is removed and replaced, there is more labor than you would think. Aside from the routine un-cowling, the drive gear must be removed after the engine crankshaft is locked. Both drive gear and gear box gear and matched and since one is replaced on the gearbox the other must be replaced as well. Once installed the gear has to be measured with a dial indicator to verify it is within run out specs.
    The threaded inserts in the prop flange must be removed and reinstalled in the new prop flange (press fit). If you have a prop extension/spacer, that must also be removed and installed on the new flange. Then mounting the prop and checking the track. Obviously everything has to be torqued to the required spec.
    I found it very time consuming removing the threaded inserts and separating the extension (without damaging the pieces). My prop extension/spacer fits almost like a press fit with the threaded inserts. Little things like that can take far more time than you would think. Of course your airplane has different requirements and fit issues so it is difficult to compare similar projects.
    I would say I probably spent at least 5 hours in reassembly time only on the last gearbox change.
    Since you asked about labor charges I can assume that you may disagree with your final bill. Hopefully you were given a written estimate. For owners and service technitions the time to discuss the cost of maintenance is before the work is started not after it is completed.
    Everyone should ask for an estimate (obviously this does not apply to warranty work) and anytime the mechanic sees that prices are going to be higher the customer should be advised and given a chance to approve the increase.
      
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  • Re: Noticeable vibration at 200+ hours 912iS Sport

    by » 6 years ago

    If everything that Porter mentions has to be done then absolutely time can add up. This can depend on different aircraft. Some are as simple as un-bolting the prop and pulling the gearbox and it's off. Remember to ALWAYS use a puller for the gearbox and NEVER hammer or pry it off.

    p.s
    I was just reminded about using the proper terminology. I was getting sloppy in my terminology.
    We do not rebuild with Rotax. It is either repair or overhaul. I know the FAA likes the term "repair" for what most of us call a carb overhaul. I even know of an instance or two where the FAA told a mechanic that very thing when they reviewed a logbook. In the case of the gearbox which had an issue repair would be the proper term.

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell

      
    Report

  • Re: Noticeable vibration at 200+ hours 912iS Sport

    by » 6 years ago

    Flying home behind the rebuilt gearbox tomorrow or Wednesday.


    Flew home today. No vibration. Problem solved for now...

    Aviation Real Estate Specialist & iRMT

      
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