I am new to this forum and have one question:

When is it necessary to purge the engine oil system? I am working on an Rotax 912 engine, previously bought, and need to do some Service Bulletins. The SBs does not ask for purging, however a friend of mine said this needs to be done after each maintenance.

Can someone help me out on this one with an answer? 

Thank you!



  • Re: Oil purging

    by » 10 months ago

    First off, read the various ROTAX maintenance manuals (Operators, Installation, Line, and Major) for guidance at:  https://www.rotax-owner.com/en/support-topmenu/engine-manuals#912-series-engines

    The basic guidance is that any time you open up certain portions of the engine's oil system a PURGE may be necessary.  Opening up the oil system has the potential to introduce unwanted air into the oil lines thus interfering with the oil pump's ability to provide (suck/blow) oil flow throughout the engine.

    Having said that, I have found that the above guidance is appropriately conservative.  For example, I have an RV-12 (912 ULS) with a mid-mounted oil tank.  I can safely disconnect the oil input and output lines at the top of the tank to clean the oil tank without having to then perform a PURGE -- my actions have introduced no extra air into the oil lines.  Your aircraft's engine installation may be different -- so be careful.

    ps -- Don't confuse PURGING with BURPING.  PURGING is a more complicated maintenance procedure that requires an air source, pipe caps, etc. and is required only occasionally.  BURPING is a regular occurance that is used to assist in accurately determining the quantity of oil in the engine.

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