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Hi everyone

today I want to discuss about crankshaft out of round

I checked Rotax912 uls engine after prop. strike and I found :

(refer to the overhaul manual appendix) 

prop. shaft out of true is ok ( 0.04)

overload clutch is in limit ( 650 N.m)

but crankshaft out of round is more then max. wear limit 

max. wear limit = 0.06

actual reading = 0.08

refer to the operator manual :

(overload clutch will also prevent any undue load to the crankshaft in case of ground contact of the propeller.)

now my question  :

Is it possible that crank shaft damaged when prop. shaft and overload clutch is ok ??

How much  reasons are for crankshaft out of run ?

 

thanks 

 

 

  • Re: crankshaft out of round

    by » one month ago


    Yes it's possible. There are several factors at play.


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


  • Re: crankshaft out of round

    by » one month ago


    Thank You

    Can you tell me some reason, I don't want this happened again.  


  • Re: crankshaft out of round

    by » one month ago


    It could depend on several factors. How the prop hit (just the tips vs the entire prop wiped out) what prop Mfg, rpm at strike, what did it hit, did the engine keep running or did it come to a stop, gearbox clutch clogged with lead from 100LL, age of the engine, ect...


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


  • Re: crankshaft out of round

    by » one month ago


    the propeller was MT 3 blade after touching the ground , engine stopped and more than half of two blade is destroyed and one blade is ok 

    the TBO of engine is 1500 hr.    and they don't use 100LL 

    thank you,

     


  • Re: crankshaft out of round

    by » 4 weeks ago


    Hi all

    Just to be sure remove the crankshaft drive gear retaining nut and then recheck your readings.  Be sure to have at least one spark plug removed from each cylinder when you do the rotation to avoid compression  build up causing erroneous readings.  

    If the crankshaft reads within the limits with the nut removed the problem is the retainer friction washer.  Replace with new and be sure when installing you center the washer as you tighten the nut on torquing.  Check again.  The hollow crankshaft is influenced by even the slightest misalignment of the nut and friction washer.  

    Be sure to also complete the crankshaft twist check that is shown in the heavy maintenance manual.  If you have sent enough shock into the crank it is possible that one of the pins has slipped.  

     

    Cheers


    Thank you said by: RotaxOwner Admin

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