RV inline fuel filter

[Notatestpilot]

Anyone install and have used this filter in their RV?(please see attached photo.)
Like to know if there’s any issues, essentially your review.
Thanks

 

[geezer]

Do you have a gascolator? They are expensive, but have about a century of incremental improvement.

They have the following advantages:

Filter at the top
Transparent lower container on most models, to see the water or debris, some are metal, must be drained to see what is there, or, not there
Integral drain to remove contaminants
Outlet at the top to the engine, will not pass water until filled


The filter you depicted is opaque, how do you know if it is full of water? Clogged with debris? How do you drain it periodically? If it clogs, your gas flow is stopped, even though you have plenty of gas, OK in a car, not in a plane.

Years ago, before I became a pilot, I bought an inline filter for my first new car, clear chamber, mounted vertical, it had a drain screw to remove water, and could be dis assembled to blow air through the filter element to remove debris. One of the gas stations I used had occasional problems, and this filter kept my carb clean.
It functioned much as an aircraft gascolator.























;

 

[Dan Thomas]

I think the OP is referring to a Recreational Vehicle (motorhome) rather than an RV-8 or whatever.

 

[Notatestpilot]

Nope!
My RV6....thanks.

 

[nauga]

Are you proposing using this on the feed from each tank? Or a single in the main feed? Bypass? My first reaction was that if the screen gets blocked or even partially blocked you'll have no fuel or restricted flow. At least it doesn't look like it has an element that will swell up and block if it swallows water, as some are prone to.

Nauga,
who prefers a gascolator

 

[Dan Thomas]

Nope!
My RV6....thanks.

Don't use it. As Nauga says, you can't monitor it or drain it before flight.

 

[kmacht]

They are common on the sonex line of aircraft. A gascolator doesn’t work with the aerocarb because the aerocarb needs to be the lowest point in the fuel system with a straight downward sloping line from the tank or else vapor bubbles cause the engine to stumble. These in line filters are the only thing that works in the limited space available and are what the factory uses instead of a gascolator now. Standard practice is to replace them every annual. There is also a tank finger strainer before the fuel gets to the filter. Some have also used the ones with a clear housing that can be inspected before flight but they are not made as well. The sonex is a pure gravity fed system so if you have a fuel pump on your RV then your experience may be different. If a gascolator works in the standard RV setup I also wouldn’t recommend deviating from it unless there is a really good reason.

 

[Dana]

Transparent lower container on most models, to see the water or debris, some are metal, must be drained to see what is there, or, not there
Integral drain to remove contaminants
Outlet at the top to the engine, will not pass water until filled

I don't think anybody makes a clear bowl gascolator for airplanes any more, might have been an AD to replace the glass with a metal tube? Only glass ones I've seen in recent years are for small engines and antique cars, with no drain.

 

[geezer]

Our 1960 Cessna 150, and 1962 172 had glass, and I think our next one did too, but later ones had metal. Always drained some fluid on preflight. One required 2 people, as the drain was cable remote from the oil filler hatch, drained under the cowling, lazy check, drain until sure that the puddle was gas, no beads of water.

 

[donjohnston]

Velocity's run these. While not exactly the same, they appear similar.

#6 40 Micron Maintainable Fuel Filter - AIRFLOW PERFORMANCE

FUEL FILTERS MANUAL 40 Micron Filter Element

airflowperformance.com

Has worked fine for me. I cleaned about once a month until I stopped seeing fiberglass dust in it. That took about a year.

I haven't seen a gascolator on a Velocity in at least 20 years.

 

[tsts4]

99.9% of the US built RV-10s, myself included, run a similar inline fuel filter with no gascolater.

 

[FORANE]

Interesting so many use this sort of filter. I'm a big fan of experimental but apart from a few aforementioned specific use cases, why divert from the well trodden path in such a critical component?

 

[kyleb]

Interesting so many use this sort of filter. I'm a big fan of experimental but apart from a few aforementioned specific use cases, why divert from the well trodden path in such a critical component?

In the rv’s, you’re gonna find any water in the fuel when you sump the tanks. Beyond that, gascolators are a really good way to add heat to your fuel and cause hard hot start and other warm fuel problems.

I have a gascolator on my carb’d RV-6 but have an inline filter on the RV-10, which is fuel injected.

 

[Daleandee]

They are common on the sonex line of aircraft. A gascolator doesn’t work with the aerocarb because the aerocarb needs to be the lowest point in the fuel system with a straight downward sloping line from the tank or else vapor bubbles cause the engine to stumble. These in line filters are the only thing that works in the limited space available and are what the factory uses instead of a gascolator now. Standard practice is to replace them every annual. There is also a tank finger strainer before the fuel gets to the filter. Some have also used the ones with a clear housing that can be inspected before flight but they are not made as well. The sonex is a pure gravity fed system so if you have a fuel pump on your RV then your experience may be different. If a gascolator works in the standard RV setup I also wouldn’t recommend deviating from it unless there is a really good reason.

I just wanted to put in my 00.02 to say that my particular gravity fed aircraft with a Marvel Schebler carb has a gascolator ...

 

[kmacht]

I just wanted to put in my 00.02 to say that my particular gravity fed aircraft with a Marvel Schebler carb has a gascolator ...

My comments were specific to the aerocarb. A marvel Schebler carb has a float bowl that allows for any air bubbles to not interupt the engine. The aerocarb has no float bowl so any interruption in fuel flow, even a small vapor bubble interrupts the engine and makes it stumble. I don’t recommend it for an RV but that is why many Sonex use that inline filter instead of a gascolator.

 

[Daleandee]

My comments were specific to the aerocarb. A marvel Schebler carb has a float bowl that allows for any air bubbles to not interupt the engine. The aerocarb has no float bowl so any interruption in fuel flow, even a small vapor bubble interrupts the engine and makes it stumble. I don’t recommend it for an RV but that is why many Sonex use that inline filter instead of a gascolator.

I'm aware of the difference between a slide carb & a float bowl carb. I tinkered & flew an aerocarb for ~200 hours. I don't have any intention of ever flying behind another one. I have reasons for that but mostly because of the hesitation and stumbles that are caused when using them. Here's an example:

Engine stumbles during take-off

The aerocarb is the reason some Sonex aircraft have ditched the gascolator. I'm not certain that's a great idea ...

 

[Dana]

Another issue is that the VW derived engines which power most Sonexes won't windmill due to the small prop and thus won't automatically restart when fuel is restored... one more reason you don't want it to "stumble".

 

[Dan Thomas]

I don't think anybody makes a clear bowl gascolator for airplanes any more, might have been an AD to replace the glass with a metal tube? Only glass ones I've seen in recent years are for small engines and antique cars, with no drain.

I have one. It came off my Jodel. That glass cylinder was 1/4" thick but I still didn't trust it. The head was cast zinc, so the total weight was not airplane-friendly. They were meant for tractors of the 1930s and '40s. I machined an aluminum gasolator for the airplane.



The brass screen came from a reusable coffee filter. The bowl bolt was stainless.

 

[455 Bravo Uniform]

Nice!

Any concern with SS bolt into aluminum threads? Galling? Galvanic corrosion? Or is there a threaded fitting in the top?

I know enough to be cautious, but that’s about it.

 

[Dan Thomas]

Any concern with SS bolt into aluminum threads? Galling? Galvanic corrosion? Or is there a threaded fitting in the top?

Some say there is, but I have seen stainless sheet riveted to aluminum, chiefly as firewall sheet to aluminum fuselage. After many decades it's still there in every airplane I've worked on. I've also seen stainless fuel fittings used in aluminum bulkhead fittings in large-aircraft tanks. Then, of course, there are the many stainless exhaust systems bolted to aluminum cylinder heads. Sometimes the flange gaskets are stainless, too. In Lycomings, the spark plug threads are a stainless Helicoil in that aluminum head.

Galling is a problem, but usually with stainless threads into stainless threads. We used Nickel Anti-seize there.

The bolt threads were tapped directly into the aluminum head in my gascolator.

The Cessna 180/185 and oldest 182s have stabilizer trim jackscrews. These had, originally, steel screws that ran in steel tubular nuts, all in an aluminum housing. Corrosion was a big problem, especially with airplanes on floats, and especially in salt water. The galvanic action between the aluminum and steel was no doubt a factor. These parts are obscenely expensive from Cessna, so McFarlane came out with stainless screw and nut and stainless chain, and the original aluminum housing is used in the rebuild. The kit comes with a new stainless chain, too. Much better than the old steel chain.



One part that McFarlane doesn't have is the mounting bracket. Cessna calls it a "hinge." It's the item pointed to in the picture here. About the size of a golf ball.

Before I retired six years ago they wanted, if I remember right, seven thousand bucks for one. There are left and right in each airplane. Two jacks. That hinge is probably just 7075T-6 or similar, and could be made with a lathe and mill, but if it fails you lose trim control. If they both break you crash. Monstrous liability.

 

[Spring Ford]

Any concern with SS bolt into aluminum threads?

There is - if you have a boat on the ocean.

Commonly used and the recommendation often seems to be remove bolt and re-apply anti-seize every year.

No one seems to bother. And they sometimes snap off on attempted removal.

On an aircraft, I think it will probably last a long time.