Finding out TBO

Download the Maintenance Manual (Line) here:

https://www.rotax-owner.com/en/support-topmenu/engine-manuals#912-series-engines

See Chapter 05-10-00, Time Limits.  There is a table of TBOs by engine type and serial number on pages 4 & 5 of that chapter.

There's lots of other good maintenance info in there too, so definitely have a look.

TBO in some cases depends on whether or not certain service procedures were performed.

And your engine may have a unique configuration and that will affect the applicable service bulletins.

To get detailed information on your engine, post the serial number here and I can look it up.

The first thing you need to know in order to determine a checklist of potentially applicable service bulletins is the date of manufacture. Armed with that data you can use our service bulletin search engine to generate a list using the "By Engine Type" search option, and filling in a date range starting with the month and year of your engine production date. NOTE: a serial number search option is provided - but due to the structure of the various bulletins, that is not going to generate a complete list - Engine Type combined with date range is the most effective way to get a list specific to your engine.

Thanks for the response.  I fear I'll be opening a can of worms, but it must be done.  The Serial number is 3792952

3792952 was produced 26-June-1991.

Engine Type: ROTAX 912 UL

Model Number: 309120010

26-June-1991 means that the engine is way past its TBO, and it predates the electronic engine database, so I cannot pull up any detailed configuration info for you there. You can however still search for a full list of all applicable service bulletins over the years - and then check the engine logbook to see if they were all complied with.