Screen on Fuel Vent

On the -8 the vent is just the 1/4" tube cut off at an angle. I bought a bulk head fitting that is cut to be a vent but this does not work on the -8 due to the double floor, there is no way to tighten up the nut. I was making a screen to go over the opening of the tube and I wondered if this was more harm than good. If there was no screen a bug could clog the hole, but it also could just go all the way to the tank and not clog the vent. I am thinking the screen will act like a collector, now smaller bugs will stick between the screen openings, after going through a few bugs you would get an obstruction. Now if icing were encountered to me the screen would collect even more ice than if there were no screen.

Anyone flying with a screen on the fuel vent on the -8 have any issues with bug guts collecting on the screen? I you don't have a screen do you get debris in your tanks?

Pictured are my screen in the works (I will smooth the JB weld once set up) on the vent tube and a shot of the AN fitting I bought that I can't use, or at least I can't find a way to make it work on the eight. I am using a garden hose screen that is stainless steel; it has a more open mesh than some of the brass screens I have seen.

This is my screen in the works, I am using JB weld for this prototype.



This is the AN fitting vent, the screen is very fine mesh not in the direct wind stream.



Cheers

Which direction ?

Mike, isn't the vent supposed to face into the wind to slightly pressurize the vent return line. I think some folks also drill a very small hole in the back side just in case the front screen side might ice or clog.

Bill S

My vent is just like that (on a 6). I get lots of bugs on the airplane but have had no problems with the screen covered vent in 10 years.

Interconnect.

I don't know about the 8, but on my 9 there is two vents, one for each tank. I interconnected the two lines at the top, under the panel, so if one would clog up, during flight, both tanks still vent through the other one. Obviously a clogged vent would be cleaned before the next flight.

I did drill the holes to, to avoid the vents to ice up, but now I am wondering if this is not making things worce, because the pressure is now less, if not all gone?

Regards, Tonny.

Bonaco Inc

Bonaco Inc. has a fuel vent fitting with a screen installed. Bought a pair for my 7A. http://www.bonacoinc.com/index.htm did not see them on their site but give them a call and they will know what you?re talking about.
Squeak

screens on vent lines

I'd be more concerned about mud dauber (sp?) wasps building nests in unscreened vent lines than bugs covering the screened openings in flight. However the hole drilled on the aft side of the an fitting sounds like a good idea to mitigate the screen clogging risk. I know of 2 RVers who had BOTH unscreened vent lines plugged by wasp nests. One made a forced landing, the other discovered it when he opened the tanks to inspect fuel levels and was greeted by a rush of air.

Doug
RV6

I have the Bonaco

Squeak said:

Bonaco Inc. has a fuel vent fitting with a screen installed. Bought a pair for my 7A. http://www.bonacoinc.com/index.htm did not see them on their site but give them a call and they will know what you?re talking about.
Squeak

Click to expand...

The Bonaco fitting is the lower picture in my post that started this thread. I did not realize when I bought the fitting that it just does not work well with the RV-8 since it has a two layer floor where the vent exits the cockpit. I would have to open up the interior floor so that I could tighten down the bulkhead fitting. The plans for the RV-8 call for running the tube to the outside of the aircraft and make a bend and then cutting off at an angle perpendicular to the wind.

Cheers

Screen it down South

Here in Florida we have many mud daubers and I know of a tiger that had to make a forced landing do to one in his fuel vent. I stretched a couple layers of nylon stockings over the hole and finished it off with small zip ties that matched the paint color. You can select your mesh size depending on how tight you stretch it. You can easily remove and replace them and there have not been any bug build ups.

I have noticed a loss of fuel pressure at high altitudes that I did not seem to have before the screens. I now have to turn on the fuel pump about every 10 to 15 minutes when flying at 10,000 feet. On a long eastbound cross country, I will take them off if I think about it.

They are very durable, I am still using the same ones for over two years.

Cover it when parked.

I'm not flying my -8 yet, but...

I used to have a plane that had forward facing fuel cap vents. I would always cover the vents with a piece of rubber fuel line hose with a screw stuck in the end and an orange streamer hanging off to prevent mud daubers or others from taking up residence in them. On every preflight and every time I refueled, I would remove the caps to visually check the fuel levels and would blow through the vents to ensure they were not clogged. I never noticed a problem with them actually plugging while in flight.

I know a professional pilot who used to have the same kind of plane that I had. After attending a fly-in in the southeast in 1999, he departed back to the west and overnighted somewhere along the way. The next day, continuing on to his destination, he lost fuel flow and the engine quit. There was a hard landing with serious injuries. It was found that a caterpillar was stuck in one of the fuel vents. The last time I talked to him a couple of years ago, he had still not returned to work due to a double vision problem.

When I get mine flying, I will cover the vent anytime it is parked.

Wow thanks for all the input
SmilinJack

Coming up on 10 years and about 1,000 hours on my -8 with no screens on the fuel vents.

The YP is hangared, but when I'm out and about I have plastic caps for the fuel vents with the "Remove before Flight" reminder on 'em.

No problems. Apparently all the big cloggy bugs here in Maine go right for the windscreen...

I made the vets for my -6A out of bulkhead fitting I turned down and cut at an angle. Rather than pro-seal on a small screen I pressed in the couple of the last-chance screens from a carborator inlet seat. They are in there tight and I don't expect them to move. This gives more surface area than a small screen, we'll see how they hold up over time.

I was concerned about wasps too, and incorporated an idea from an earlier poster, but don't recall whose it was. Bend a piece of .032 lockwire about an inch long, basically doubling it back on itself. Insert this into the fitting you cut off for the vent. The middle (point of the bend) won't fit inside and the size of the wire effectively allows the vent to function but decreases the opening (by making it two parts) so no bugs can fit inside. My has been in place for a couple of years, will not fall out, and the vent works fine. No cost, no fuss, looks better that gooping on a screen and it works!

fuel vents

I don't have screens on my vents, BUT I stick pipe cleaners in both vents and the fuel pump overflow line when it is parked. I've never seen a bug on either vent or the fuel pump vent. Dirt daubers will clog the vents during the summer months in the south if they are left open though. I've had two friends make forced landings with injuries because of clogged fuel vents. Pipe cleaners work very well......I use red ones because they are easy to see.