FAB By-pass

So I am finally getting around to installing the FAB by-pass kit that Vans put out last year. My kit is in the mail so I have not yet looked at the instructions, but in the pictures of Doug doing his install for the new engine and others I have seen it seems the door is being installed on the bottom of the glass scoop.

I thought part of the reason for it was to bypass the filter if it became plugged? The way my FAB works (0-320 with carb) is the filter has a plate on the bottom of it between the filter and the FAB box. So if the door flips up due to the inlet being plugged that's fine, but if the filter itself is plugged then the door won't help.

Is the thinking that it is not possible to block the entire circular filter element?

Andy,
I just finished installing mine and if the filter is clogged then it will bypass. If the carb ventury is iced then the bypass will not help.
It is for the inlet or filter being blocked only.

Hope this helps!

FAB bypass door

Andy,
The bypass door is INSIDE the ring of the air filter. If the air filter plugs with snow/ice, the bypass door will open due to the suction generated by the engine. Otherwise, the magnet keeps it closed. But, even with the bypass door, you should pull carb heat ON when flying in ice/snow so that the door never has to open, the air filter never gets covered with ice/snow, and so that you don't develop a carb ice problem. Will you know if your air filter is plugged and the door is open? Maybe not. Do you care? Well, I do because the bypass door is there as an emergency backup and it is unfiltered air... not really intended for normal operations.
Mark Andrews
p.s. I try to avoid flying in snow/ice.

RV9 plans for FAB not like the others.

Andy, you're right...
On the 9A plans there IS a metal plate on the bottom of the air filter that holds it in place, unlike the others that I've seen where the fiberglass shell of the airbox presses against the bottom of the air filter.

So, I don't know where the bypass would go either... maybe a door on the top between the carb and the inside edge of the filter? I thought I saw this done on someone's website somewhere.

-Clay

more glass work

I finished my bypass a few weeks ago. You cut a hole in the fiberglass bottom then lay up a lip between the fiberglass and the bottom al plate. That way when the door opens it's outside air coming it. The ploblem is that it will not be heated air, probably a bit warmer because of where it's coming from, but not heated.

The O-360 FAB and the O-320 are different. The O-360 uses the bottom of the fiberglass to seal the filter while the O-320 has a metal plate to seal the bottom of the filter. There are two different by-pass types. The one for the O-360 FAB uses the fiberglass and one for the O-320 mounts on the metal plate below the K&N filter.

Ken

0-320 Carb Filter Bypass

Cam, Andy & Clay,

Does the the new cable actuated filter bypass apply to the o-320 carb airbox? If so, did you guys install it, or did you stay with the magnet?