In line fuel filter

[Elkonastick 10]

Hi everyone,

 I just had my conditional and found only three things needing looked at. One of my ignition coils (EA81 soob) has a broken mount screw, glass inline fuel filter under panel and a section of fuel line that looked questionable. He doesn't like the glass inline filters, can't say I do either. Screw replacement will be easy peasy. But filter and fuel line I'd like some advice from you guys with way more experience than me.

I have a plastic inline paper filter just upstream of header tank also. The glass filter is after the fuel shut off valve under the panel. My question is this. Is the second filter after valve needed? Wouldn't the filter at header tank be sufficient? It seems the filter after the shut off valve is just two more places a Leak could develope, and it'd be right on my legs! 

Unless the concensise is two filters are needed I'd like to eliminate the second filter. If it is needed I'd like to get rid of the glass and move it out from under panel. Also is the plastic paper type filter a good choice? Any drawbacks to them? Better alternative?

There is a section of fuel line under panel that at first "squeeze" seemed like rubber line that had gotten hard. Upon closer inspection it doesn't look like run of the mill rubber line. No writing on it, seems to have a hard plastic outer layer? It may be just hard rubber line needing replaced, but it doesn't look like any rubber line I've seen. Is there a special "hard shell" line out there that would of been chosen for the section under the panel that has better strength? 

Thank you all for any advice!

Darin

[1avidflyer 1983]

Unless you were to have the two filters side by side, I can't see the point of having two unless the first one had larger mesh and the second one was just for catching small stuff.  For a while when I was worried about junk coming out of the tanks, I had two filters controlled by separate valves.  I would take off with both on, in flight I turned the one off.  The thought was, if the one plugged up in flight, the second one could come on line and I would still get fuel.  When I rebuilt the plane, I didn't reinstall the second valve and filter.  By rights, you should have finger strainers in the tank outlets, the header tank behind the seat acts as a gascolator which should trap dirt and water, and lastly the filter near the panel if you have one.  How many more should you need?  I'm using a glass filter in the Avid now.  Seems fine.  Some say the paper filters can trap water and plug.   Probably true.  I used to use them and never had problems with them, but maybe I was just lucky to never get any water going through them.   JImChuk 

[akflyer 1427]

I have had issues with a paper filter plugging off with water when it looked clean on first glance.  I won't use a paper filter in my systems anymore.  Only the electric boost pump saved my bacon by being able to keep enough fuel flowing to get back to the lake.

 

Glass filters got a bad wrap when cub drivers stuff one in and glass bowl on the gascolator breaks sending gas onto a hot exhaust system.  I am torn on this one as it seems to me that we have tanks right above our heads that are more likely to split and cover us in gas than a little filter under the dash.  I don't have a glass bowl on my short wing death trap for the reasons mentioned above but I think it more of a feel good thing than anything else.  Chances are, if you hit hard enough to break the glass filter under the dash, that will be the least of your worries.

 

Edited 16 Sep 2019 by akflyer

[Elkonastick 10]

Thanks for the input guys, I do appreciate your insight. I've heard the water issue with the paper filters before. The AP said the o-ring on the glass filters is prone to failure? 

What is a good replacement for the plastic paper filter? I know I'm probably asking a Ford, Chevy, Dodge type question but even a top of the line filter is a small expense considering the outcome of a failure from going cheap.

Searching the interweb seems like I'm chasing my tail trying to decide on a good quality screen type filter, micron size, etc. 

Thank you again

[akflyer 1427]

Thanks for the input guys, I do appreciate your insight. I've heard the water issue with the paper filters before. The AP said the o-ring on the glass filters is prone to failure? 

What is a good replacement for the plastic paper filter? I know I'm probably asking a Ford, Chevy, Dodge type question but even a top of the line filter is a small expense considering the outcome of a failure from going cheap.

Searching the interweb seems like I'm chasing my tail trying to decide on a good quality screen type filter, micron size, etc. 

Thank you again

about as prone to failure as the orings in the engine, the Curtis drain valves, fuel shut off valves etc.  Can he quantify his opinion on the oring failures?? or is it just his opinion.  If he is squawking about this, I would be apt to find a different AP to deal with.

 

[Allen Sutphin 705]

I used the Purolator glass filter for years, never had a problem. I did have mine safety wired though to keep everything tight. Changed the screen every year at inspection.

[SuberAvid 617]

As I have mentioned before, I have my glass filters above the header tank where I can easily see them, so I know when fuel is flowing.  And they saved my bacon once when I had water leak around my gas cap vent and I was able to see it coming in through the glass filter.  I am a believer in them for that reason.  I also have a second filter before the flow sensor because that takes a finer filter.  So maybe I am over doing it but I have the finger screens, the glass filters, the finer filter at the fuel flow sensor and then a couple more that screw into the backup electric fuel pumps (left in place from when I had the Subaru and these were the primary fuel pumps).  Yeah, I know, and you thought two was to many....

[Yamma-Fox 403]

Ive asked this question here in the group before and through their advice have found myself in the camp of less filters.  Especially ones in the gravity feed side where it takes just the littlest blockage to stop the "trickle down".

I believe the finger strainers and the  header tank (as a) gascolator will do fine in that secton and am planning a simple plastic cased plastic mesh filter after the fuel pump and before the fuel pressure guage and carbs:

https://www.amazon.com/gp/aw/d/B00K24I1Y6/ref=ox_sc_act_image_1?smid=AQFP6DEPUVK7X&psc=1

Edited 1 Oct 2019 by Yamma-Fox

[Yamma-Fox 403]

Anyone have objections to a filter like the one in my last post?  Seems like a good compromise with plastic instead of glass case and also not bieng paper mesh.  It looks like it would take a ton of "crap" to block it up..  especially with a 4psi fuel pump pushing through it.

Edited 1 Oct 2019 by Yamma-Fox

[1avidflyer 1983]

I like the looks of that plastic case/ mesh inside filter.  Seems like the best of both worlds.  And I agree on not having filters on the gravity feed of the header tank.  Had one off field landing because of it, good thing there was no damage.  Did give my neighbor a surprise though.  JImChuk

[Fly-n-Low 181]

I have two glass screens from my tanks to the header where I can see them. Then two smaller filters, one per carb, under the cowl.

I really don't like my on and off valve as it is not an aircraft part. I did replace the cheap primer with one from a Piper. Much better!

Edited 1 Oct 2019 by Fly-n-Low

[Turbo 162]

Geez, whatever you do, don't put a filter upstream of the header tank/gascolator!!  The whole point of a gascolator is to trap any water that might get into your fuel tank via thermal respiration.  A filter upstream of the gascolator will eventually fill with water, and the water's high surface tension will stop the flow of fuel.  This happened to Leni, and I have validated this phenomenon in my lab (garage).  Leni's butt was saved by a powerful aux fuel pump. However, too much fuel pressure can overpower the float-bowl needle valve and disable the fuel-pressure regulation the carb's float bowl is supposed to provide.  One fuel filter, downstream of the header tank, but upstream of the diaphragm fuel pump is all you need.

[Yamma-Fox 403]

And I'm putting the one filter after the fuel pump(s) as opposed to before it.  Let the finger strainers and header-gascolator take care of the pump filtering.

Just seems better to push pressure through a filter rather than suck through it.  Especially if it were to partially clog.

I'm also tapping the fuel pressure guage after the filter to be able to see (from the drivers seat) if it ever is getting clogged.

[flywise 169]

I used the andair cleanable inline filter. Over time it's cheaper than single use versions. It filters 62 Microns with very little pressure drop (Rotax specs maximum 100 micron filter)

 

https://www.aircraftspruce.ca/catalog/eppages/pump05-12560.php

 

[Allen Sutphin 705]

And I'm putting the one filter after the fuel pump(s) as opposed to before it.  Let the finger strainers and header-gascolator take care of the pump filtering.

Just seems better to push pressure through a filter rather than suck through it.  Especially if it were to partially clog.

I'm also tapping the fuel pressure guage after the filter to be able to see (from the drivers seat) if it ever is getting clogged.

All automobiles now pretty much put their pumps in the tank. They learned that it is easier to push fuel than to suck it to the engine. And they usually push it thru a filter, too.