intake air filter choices

john smith wrote:
Dick wrote:

After using a lawn tractors slightly oiled, green foam filter on my
experimental with C-85, a fellow remarked that it was much too thick (about
1") as I replaced it.

Just wondering what non-certified (read cheap G) alternatives that others
are using. Seems like most guys use a pleated paper-like filter...

Thanks Dick



Foam filters have a history of coming apart, getting sucked into the
carburetor, and causing blockages which results in the engine stopping.
Makes for interesting emergency landing explanations.

We've been using the Brackett foam filters on our training
airplanes for 14 years (and 13 airplanes, five or six at any one time,
hundreds of hours per year per airplane) and have had no trouble
whatever. The filters work well enough that the engines reach TBO with
the compression still in the high 70s, even though we do a lot of
training off dirt strips, and are cheap to replace. It's not an oil in
the Brackett filter, its a glycerine or silicone goop of some sort.
Can't try to wash and re-oil it. It needs to be replaced yearly in any
case to prevent decaying foam getting into the intake.
There have been a couple of ADs against the Bracketts: one
involved the rear screen (aluminum) vibrating and flexing then breaking
and entering the engine; it was superceded by a steel-screened frame.
The other was to do with the filter frame/airbox gasket on some models
getting sucked in; another revision fixed that.
Every time we get another airplane it gets a Brackett.

Dan