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Unable to reach 2000hrs TBO on P2002-JF

in 912 / 914 Technical Questions 13 years ago

  • Re: Unable to reach 2000hrs TBO on P2002-JF

    by » 13 years ago

    I hope we are talking about a Rotax 912ULS or UL here? It could be a poor oil. You should be using a semi synthetic for 100LL and a full synthetic for auto fuel.

    I would like to know what the engine rpm is and not the prop. The engine should be getting 5500-5600 rpm WOT flat and level.

    Let's start here before we try to do anything else.

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

      
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  • Re: Unable to reach 2000hrs TBO on P2002-JF

    by » 13 years ago

    Hi Roger and Alistair
    These are 912 S2 certified engines with prop geabox reduction ratio of 2,43 :1
    Oil we got is AeroShell Sport Plus4 semi-synthetic multigrade 10W-40
    Fuel we're using is auto-fuel (98 unleaded). You're saying that full synthetic is recommended in our case. On the oil can this is written that this oil is suitable for engines using Avgas or unleaded fuel.

    The symptoms that each engine had was that on the static run they where not reaching minimum prop rpm's of 2000rpm. This is very difficult to get a feedback from the engine-shop about the damage.

    Many thanks
    Thierry
      
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  • Re: Unable to reach 2000hrs TBO on P2002-JF

    by » 13 years ago

    Hi Thierry,

    If you use auto fuel you can use either full or semi synthetic. If you use 100LL you need to use a semi synthetic. A full synthetic will not suspend the lead and it will fall out of the oil and collect in different areas of the engine.
    You are fine using Aero Shell Sport Plus 4 for either fuel.

    You keep saying you only get 2000 rpm out of the prop, does that mean your Rotax 912 engine rpm is only getting 4860 rpm? I would like to know the engine rpm not the prop rpm or at least if we are talking about the same thing. You said to that this was a static rpm so I take it this means an on the ground only full rpm run up? If you are truly running only 4860 rpm static rpm then you need to flatten the prop pitch about 2 degrees so when you are in the air you get 2264 rpm (5500 engine rpm) at wide open throttle at your normal cruise altitude. If you really have a low rpm prop pitch setting that would explain why you can't get to 2000 hr overhaul. You are overloading this engine way too much and it causes excessive wear.

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

      
    Report

  • Re: Unable to reach 2000hrs TBO on P2002-JF

    by » 13 years ago

    Dear Roger
    Many thanks for the info about the oil.
    4860engine rpm (2000rpm prop rpm) is what we need according the P2002's AFM at the initial T/O run. Usually we got 5100rpm. At best rate of climb we got 5050rpm in average, depends on weight. Cruise climb is normally 70kias on P2002. This gives 5100rpm and it seems to be too slow on the long run at WOT. This engine is equipped with a 2 blades wooden prop. Not long ago we decided to take 80kias for Cruise climb and with this we got 5225rpm (very poor ROC in the Alps). Hope it will solve the problem. Our guess is that the eng/prop combination is bad on this type of aeroplane.
      
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  • Re: Unable to reach 2000hrs TBO on P2002-JF

    by » 13 years ago

    Hi Thierry,

    WOW the Alps, that could put a little different spin on things as far as density altitude and HP goes.
    I was born just 100 miles from the Alps in Oberammergau, Germany (Munchen area)in 1953. My dad was US Army.
    Back to the problem.
    What is the elevation of the field? What size is the prop? (i.e. 64", 66", 68" or 70")
    If you are getting 5250 in a climb off the field you may be fine, but if you are saying that once you level off and are flying flat and level and are only getting 5250 WOT engine rpm then that is a problem, although here is where the a high density altitude can play a part. Just make sure you get at least 5500 engine rpm (2264-2304 prop rpm) at a flat and level WOT. Anything under the 2264 for WOT level flight is too low especially if you are flying at a high density altitude and trying to push your engine.

    If you are getting over 5500 WOT flat and level in cruise then maybe we need to take a look at your maint. program. Things like having the carbs out of sync for very long periods can cause excessive wear. How often do you change oil, plugs? I hope you are following the Rotax Line Maint manual? We have Tecnam's here and I have some at my field and they have absolutely no problems and can easily see the 2000 hr TBO and then some if they wanted.

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

      
    Report
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