Fuel Filter

Yes - there was a fuel return line but as it doesn't have a filter on it, I omitted it from my list of fittings.

I also had fuel metering (L/hr) system - it was located on the main delivery line only.

Jim Isaacs wrote:

I can’t seem to find any flow rate specs for your fuel filters online, nor any data that describes what size microns they will filter. The one I have been using has that data listed on the Aircraft Spruce website. That’s how I determined it meets the Rotax 912 IM requirement for the 0.1mm minimum micron screening, and the flow rate requirements for my particular fuel system as determined by me during the flow test (my filter meets the 150% of max continuous power flow rate and exceeds the IM micron requirement). How did you determine this without the data, or did you find that data? Thanks!

Finding specifications on these gauze filters is like finding "hens teeth". The manufacturers' seem to be reluctant to divulge micron/media area/etc. Sometimes cross checking with suppliers in diffrent countries resulted in a specification.

I went down another route -

For the most part these filters are specified as prefilter for diesel engines eg Hengst H 102 WK are specified for Mercedes 300D ( & wide range of other MB diesels). Crude I know but if they can accommodate the flow rate for a 3L diesel they will do the same for a 1352 cc petrol engine. From aging (poor) memory CAT & Cummins recommend the Baldwin filters in the same role. So flow rate will not be an issue.

As for micron - similar logic - diesel engines do not tolerate, for very long,  contaminants in their fuel, before expensive repairs are required ergo filtrations is likely to be acceptable for a petrol engine.

Added to the above - most ground based engines do not get a "pre-flight" inspection, filters are checked at the service interval - deduction- there is sufficient media/gauze area, to accommodate significant contamination, before fuel flow is interrupted/reduced.

Note: As previously stated these filters are used by many European small aircraft manufacturers' - I used them for about 11 years - ergo they must be doing the job/good.

Sean,

No offense intended but an aircraft fuel filter needs to have the micron screening capacity to capture the contamination/debris as specified by Rotax in their Installation Manual. In practice this means ensuring the filter you install meets Rotax micron filtering requirements. Your system filters may be fine for a ground based engine, however I would suggest, despite your experience, that you are taking an unnecessary risk. 

Jim Isaacs wrote:

Sean,

No offense intended but an aircraft fuel filter needs to have the micron screening capacity to capture the contamination/debris as specified by Rotax in their Installation Manual. In practice this means ensuring the filter you install meets Rotax micron filtering requirements. Your system filters may be fine for a ground based engine, however I would suggest, despite your experience, that you are taking an unnecessary risk. 

Very good - I like your sense of humour.

I like experimental/home built, precisely because the owner/pilot can make their own decisions, as to component suitability.

I have been using these filters for close to 950 flight hrs over an 11 year period. This experince? PLUS the use of the very same filters by ATEC aircraft and many other European small aircraft makers, gives me confidence in their suitability.

The nominal micron claim, of any filter, will only reflect the smallest size of particle to be captured - it does not tell you the capacity of the filter to accommodate/hold contaminants and still continue to allow sufficient fuel to sustain normal engine function - this is usually considered to be a factor of filter media surface area.

I am comfortable using automotive parts/materials (where appropriate), while ensuring the continued reliable/safe performance, of my aircraft (so far so good?).