What filters are being used?

Hello!!

What filter are you referring to?

There are two filters used in the Rotax 912iS fuel system. The coarse filter (50-70 microns) and the fine fuel filter (8-12 microns)

For the coarse filter, we suggest using a gascolator with the filter installed. The one from AND-AIR GAS375 is the best and can be seen in this link here - https://www.andair.co.uk/product/gascolator-gas375/

In regards to the fine fuel filter, we suggest the one from Rotax as it's designed to be used with 912iS (Part number 874-060).

My Aircraft came with the fine filter being a UFI 31.510.00 filter. I have done 750 hrs with these filters, changed every 100 hr. I used these for years before "Rotax" branded their "own" filter.I see no reason to change to the Rotax one which is 10 times the price. The Service Instruction when introducing the "Rotax filter" was "optional".

There is nothing "special" about a Rotax engine or the fuel that is used, I suspect that any good brand EFI fine filter will be fine.

Now I have looked it appears that the Rotax one is a Bosch 0 450 905 021 8 micron one rebranded.

Same dimensions same connections same micron rating...expressed differently as 6+/-2 =8micron.

The most important thing is the filter specifications. If you want to take your time to save some money and search out this filter, then it's up to you. The responsibility of the fuel system design falls upon the builder/manufacture as long as all the specifications of the engine are met. Rotax provides this filter just to make things easier for the builder, so they don't have to go out and search for one.