Re: Alert! Alert!

Michael Huffman <mikehuffman@...>

As a longtime homebuilder, A&P, and DAR, I echo what Jim Patillo says about checking/replacing fuel filters often. It would be nice (sorta) if the automotive/motorcycle/ultralight fuel filters had an internal bypass to allow fuel to flow if they were plugged, but I've not been able to find any that have that feature. Without that, the only way to know the filter is open is to check it or replace it frequently.

When I certificate existing an "ultralight-type vehicles" that has already been flown for some time and are being certificated as experimental light-sport aircraft (ELSA), I insist that the owner replace the fuel filter (since they are cheap anyway). In my ELSA repairman courses, I also recommend the owner do the same thing at each annual, or more frequently.

Of course, when a plugged filter is encountered, the other question is, "Why is it plugged?" Is there contamination in the tank that needs to be cleaned out? Is some sealant material becoming dislodged? Is the fiberglass disentegrating? It bears examining the plugged filter to try and find out.

A couple of other things regarding filters bear mentioning:
a.. There have been reports that some paper-element automotive filters do not stand up well to aviation fuel. Unfortunately I cannot narrow down that statement any further.
b.. I have seen the cylindrical glass filters installed upside down (so the flow is in the wrong direction). If that is the case, the filter element can come loose inside the glass cylinder and block the output port (which is really the input).
Take it for what it's worth--free advice!!

Mike Huffman

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