fbpx

 

In the 912 Operator's Manual it says that an engine cooling run for 2 minutes should be performed. We now have a Tecnam P2004 Bravo, P92 Echo mk.II, and a P2006T. Each manual has a different recommendation for cooling.

P2004 Bravo: 3000 rpm for 2 min

P92 Echo mk.II: 2900 rpm for 1 min

P2006T: Idle rpm for 1 min

Are there certain temperatures we should be looking for? Our shortest taxi back would be at least 1-2 minutes at a minimum so I would expect that after a decent and landing, plus the taxi, that any excess heat should have been dissipated. Does anyone here do anything different?

Thanks!

  • Re: Engine Cooling Before Shutdown

    by » 4 months ago


    Given that Rotax 9's ignition/combustion is optimised for flight rpms I sagest that ground operating rpms should always be kept to a minimum. Your taxi run "at least 1-2 minutes "plus shut down procedures conducted by all careful pilots, probably another 2 minutes and parking, engine inlets into prevailing wind, should be sufficient.


  • Re: Engine Cooling Before Shutdown

    by » 4 months ago


    Sean said,

    "I sagest that ground operating rpms should always be kept to a minimum. Your taxi run "at least 1-2 minutes "plus shut down procedures conducted by all careful pilots, probably another 2 minutes and parking, engine inlets into prevailing wind, should be sufficient."

     

    I agree with Sean.

    Ground taxi and engine shutdown procedures should be plenty.


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


  • Re: Engine Cooling Before Shutdown

    by » 4 months ago


    I agree with Sean and Roger - the taxi to hanger time is plenty of "cool down"...  

    I saw a study done by the folks at Tornado Alley Turbos with heavily instrumented engines.  It showed that ground running did NOT cool the engine down at all.  In fact, every engine they tested saw increased heat after ground runs.  Even the turbocharged and turbo-normalized engines saw their turbo oil temps RISE du ring the 1-minute "cool down" stated in the manuals.  I believe Cirrus actually changed their manuals after studying the TAT data.


  • Re: Engine Cooling Before Shutdown

    by » 4 months ago


    James N Parker wrote:

    I agree with Sean and Roger - the taxi to hanger time is plenty of "cool down"...  

    I saw a study done by the folks at Tornado Alley Turbos with heavily instrumented engines.  It showed that ground running did NOT cool the engine down at all.  In fact, every engine they tested saw increased heat after ground runs.  Even the turbocharged and turbo-normalized engines saw their turbo oil temps RISE du ring the 1-minute "cool down" stated in the manuals.  I believe Cirrus actually changed their manuals after studying the TAT data.

    For turbo'd engines, the main point isn't a cool down, but a spin down of the turbo before its oil supply gets shut off. Modern turbo cars fix this problem but aviation doesn't get "modern" anything.


  • Re: Engine Cooling Before Shutdown

    by » 4 months ago


    In fact, just the opposite.  A turbocharger's rotational speed falls immediately when exhaust gas flow is reduced, due to aerodynamic drag on the compressor; there is no practical need for a spin-down period.  However, there is benefit to maintaining oil flow for some time while at a low power setting (and low exhaust gas flow) to pull heat out of the turbo's bearing assembly.  This prevents oil coking that can occur if oil flow stops while the turbo is still extremely hot.

    See the first two pages of this report for an explanation.


You do not have permissions to reply to this topic.