912is Fuel Filter

What Rotax is explaining is that you should replace the filter within the first 100 hours of the aircraft's operation. This is necessary due to the possibility of contamination in the fuel system from the assembly process. Often, new aircraft can have contaminants such as silicone, swarf, and other manufacturing residues in their fuel tanks. Therefore, it's a good practice to replace the filter within the initial 100 hours of operation to address any potential issues related to contamination.

What they are saying is the filter should be replaced after the first 100 hours on a new aircraft, new engine, rebuilt engine, or reworked fuel system.  The reason for this is that any fine debris left in the engine or fuel system as a result of assembly would be captured by the fine filter in the first 100 hours. After that, the system is likely flushed and clean except for particles that may come in with fuel.   The fuel system includes engine parts such as the fuel rails, fuel pressure regulator, and fuel pumps, plus the airframe components such as the fuel lines, selector valve and fuel tanks.  

After the first 100 hour filter change you can switch to a 200 hour interval unless these systems have been worked on in a way that may have introduced any debris.  All that said, a lot of folks just change this filter at every annual inspection.  

I change my 912iS filters every 100 hrs. or the annual. If someone only flew 25 hours that year I don't usually bother. 

Roger is definitely doing the right thing. The filter must be changed every 100 hours. The filter in the photo was removed from a 915iS in 170 hours and was over 80% clogged. Fuel pressure was dropping below 2.5 bar (36 psi).