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912 ULS Checking of propeller gearbox

in 912 / 914 Technical Questions 8 years ago
Hello,

Line Maintenance Manual (Chapt. 05-20-00, 5.1 Checklist/Maintenance Schedule, Sect. 14 "Checking the propeller gearbox") tells me that the propeller gearbox should be inspected after 1.000 h according to Chapt. 12-20-00, 14.2 "Checking the propeller gearbox".

SB-912-041UL R2 (dated March 2010), Chapt. 3.3 tells me that "All engines of type 912 ULS and 912 ULSFR need to receive a inspection of the propeller gearbox at 800 h TSN. [...]"

What is the right time? 800 h or 1.000 h?

I own SerNr 4.428.330 and it is now on 780 h.

Thanks
Curt

  • Re: 912 ULS Checking of propeller gearbox

    by » 8 years ago

    Hi Curt,

    This answer depends on a few factors.

    If you have a 2000 hr. TBO engine and use auto fuel then it is 1000 hrs.
    If on the 2000 hr. engine you use 100LL 30% of the time or more it is 600 hrs. Lead gums up the clutch and it needs to come apart to be cleaned of lead deposits. It can get bad enough that the lead fouls the clutch to a point it won't function any longer.

    If you have a 1500 hr. TBO engine it is 600 hrs. regardless of fuel type

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

      
    Report

  • Re: 912 ULS Checking of propeller gearbox

    by » 8 years ago


    If you have a 1500 hr. TBO engine it is 600 hrs. regardless of fuel type


    Hi Roger,
    Is this correct?

    As I understood it a non slipper gearbox was a 600hr interval.
    The gearbox inspection interval on a 912ULS (100hp) with a slipper was 1000hr but with an interim inspection of the slipper if using leaded fuel. I didn't think the engine TBO made any difference.
      
    Report

  • Re: 912 ULS Checking of propeller gearbox

    by » 8 years ago

    Hi Conrad,

    I was told this by Kodiak the America's distributor.
    The inspection of 600 hrs. is without the overload clutch or with the overload clutch and using 100LL more than 30% of the time.
    It is still 600 hrs. for a 1500 hr. TBO engine.

    To my knowledge the engines that couldn't (without great expense) extend past 1500 hr. TBO did not have the gearbox inspection extended.

    I'm sure Rob will chime in here tomorrow when he's back at work.

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

      
    Report

  • Re: 912 ULS Checking of propeller gearbox

    by » 8 years ago

    First lets clarify that SB-912-041 is refers to a TBO increase so it should not be confused with the Maintenance schedule.

    The latest maintenance schedule calls for:
    1) Both 80hp & 100hp engines have 600 hour OVERLOAD CLUTCH inspection if you are using more than 30% avgas (this is not a complete gearbox inspection, only a test of the clutch break-away force. But, if it fails the test you may as well do a complete gearbox inspection. It is not a bad thing to take the gearbox off and inspect it at 600hrs. if you have a big heavy prop and have a low idle you will save money by doing this maintenance)
    2)100hp engines only have a 1000hr gearbox inspection. 80hp engines do not have to do this inspection.
    3)100hp engines WITHOUT a clutch have 600hr inspection. this is to check for wear and correct disc spring pressure (In my opinion as it is not possible to perform a Friction-torque test when the clutch is not installed)
      
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  • Re: 912 ULS Checking of propeller gearbox

    by » 8 years ago

    Thanks Rob, that is exactly how I understood it. The service intervals on the gearbox are the same irrespective of TBO (except where the TBO is reached when a gearbox service is required anyway)

    Non slipper all engines 600Hr

    Slipper 912 (80hp) 2000Hr (or TBO if sooner).
    Slipper 912S/ULS (100hp) & 914 (115Hp) 1000Hr

    Slipper using leaded fuel needs an additional interim inspection on the slipper clutch at 600Hrs

    Rob out of interest do you carry out the slipping torque in situ with the engine/gearbox installed in the airframe - seems a lot of load to put through the airframe (particularity on the 912iS engine). I always strip the slipper out of the box to check it.
      
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