A1Skinner wrote:

gear wrote:I know of three aircraft here in the Winnipeg area (where the Cap guy is located) where they've had issues of fuel siphoning out in mid flight. The gasket gets compressed and that's when the siphon starts. We were on a long flight a few years ago and we lost 15 gallons in the air. Landed with approx. 2 gallons. I call them killer caps, same as the original cessna ones. All of those guys ripped them out and put the second generation raised caps in. If you talk to the cap guy about this, he just tells you to flip the gasket around and it will be good to go. Kinda hard to do in mid flight and fuel is pissing out,....

Garth

Garth, the caps that siphon so bad are the original caps? Or the raised Cessna caps?
David

The caps that I have experience with siphoning are the Monarch caps that are being discussed in this thread.

Ok. Thanks.

I believe this is the type of Cessna cap that has the water issue:

(the hinge of the cover goes forward)

Note the entire cap is below the wing surface.
Note the small AN fitting about halfway up the neck. This attaches to a tiny convoluted tube that snakes around the bladder to drain the bowl.
This is the ONLY bowl drain, and is usually plugged to some extent. If you look shortly after the rain, the bowl is full. The next day it may be empty. You may never know the bowl was full.

I got tired of poking safety wire in to try to clear the drain, so changed the caps.

I recommend changing these to ANY of the flush caps.aps are annoy

Monarchs:
Thoughts on the flap: 1. some people leave the flaps off. 2. the flaps can go in several ways, some work better for filling. Think it through.
3. flaps are annoying, but offer some safety, easy to learn to cope with.

Siphoning: visually check the gasket, and be sure chain is not in way to damage the gasket, when putting the cap in place. Not hard to do.

My first thought to avoid any issues with fueling out of cans with the Monarch caps was to remove the flapper. I can't believe they would have a siphoning problem from the cap vents if this was done- the monarch paperwork says the flapper is just to prevent siphoning in the event of the cap being left off. However, if the flapper is removed then the installation is not per the STC. I might call them and ask about this.
Regarding the flap-jack-cover style caps, as on the early 180's, it looks to me like the aft side of the "bowl" is lower than the neck when the airplane is in a three-point (taildragger) attitude. So while water might collect in the bowl, it shouldn't go into the tank when parked unless the tail is elevated.

My cousins '54 180 needed new bladders this fall so we added the caps since the old ones had to come off anyway. It was a good time to do this mod because there was not an extra charge from the A&P. So far he really likes them and they work great.

Our issue has been with the new venting system, we moved it from the top of the cabin to behind the left strut. We have been adjusting it but it still wants to drain the left tank first.

Trust me hotrod, after 25 years, the flaps are not a problem. The only problem I've had was when I let a line boy put the cap back on and he ripped the chain loose so it fell in the tank. I finally fished it out after 15 years. The only reason it fell in was because I wasn't paying attention and pushed the flap down with the next fill with the gas nozzle and it was like falling through a trap door.

180Marty wrote: Trust me hotrod, after 25 years, the flaps are not a problem........

Do you fuel with cans? That's the problem I foresee, I've tried to pour gas into my old Toyota pickup from cans & had to fight with a flapper similar to that on the Monarchs.

Monarchs are no problem with cans. The flapper is not like the itty bitty one in your Toyota filler.

Its a no-brainer mod if you're outside in rain country. If you're in a dry hangar then you might not need them.

hotrod150 wrote:Regarding the flap-jack-cover style caps, as on the early 180's, it looks to me like the aft side of the "bowl" is lower than the neck when the airplane is in a three-point (taildragger) attitude. So while water might collect in the bowl, it shouldn't go into the tank when parked unless the tail is elevated.

Don't believe it. ANY water retaine in that "bowl" will find its way into your tank via capillary action, creeping up the filler neck, and into the tank. A REALLY good gasket on your cap may prevent same to a degree, and for a while.

But if you park outside EVER and it rains.....OSH for example, you're very apt to get some water in your tanks. I had this problem with my 170 till I installed the Monarch kit for that.....never got a drop of water out of it after.

For those talking about fueling from cans, you are using some sort of filtration device, right? Please say you're using a Mr Funnel at the least....... If so, the funnel will poke down through the flapper. Takes a bit of getting the hang of it, but no problem.

MTV

hotrod, here's my high dollar fueling setup. Also, the only way I can see a siphon problem is if the plastic threads were made wrong and bottom out before the rubber gasket contacts the rim of the inlet.

180marty, that is a sweet set up. Where did you get the funnel and does it have a filter?

Quickdraw1 wrote:180marty, that is a sweet set up. Where did you get the funnel and does it have a filter?

It's a Mr. Funnel. Web site: http://www.mrfunnel.com/Mr._Funnel/Models.html

Wal Mart sells em, or many of the online pilot shops sell them as well.

They aren't perfect, but they're the most available, and cheap, and work.

MTV

does it have a filter?

If you look close, you can see a stand pipe deal in the middle. It has a metal screen that is coated with something that repells water. I filled it full of water once and it didn't let any pass through.

Mister Funnel, eh? First thought was of the "Mr Fusion" on the Back to the Future Deloeran.
Never seen them at my local Walmarts, but then again I never looked. MTV, how much is "cheap"?
Marty, which size is yours (they have four)? It'd be nice to have one big enough that I don't need the spout on the gas cans, and could just pour it right outa the mouth of the can.

hotrod150 wrote:Mister Funnel, eh? First thought was of the "Mr Fusion" on the Back to the Future Deloeran.
Never seen them at my local Walmarts, but then again I never looked. MTV, how much is "cheap"?
Marty, which size is yours (they have four)? It'd be nice to have one big enough that I don't need the spout on the gas cans, and could just pour it right outa the mouth of the can.

They come in a couple different sizes. Here's a link to Skygeek's price: http://www.skygeek.com/mr-funnel-f3c-fa ... fgodsHoA-A

A lot cheaper than a forced landing after water in your fuel system.....

MTV

gear wrote:I know of three aircraft here in the Winnipeg area (where the Cap guy is located) where they've had issues of fuel siphoning out in mid flight. The gasket gets compressed and that's when the siphon starts. We were on a long flight a few years ago and we lost 15 gallons in the air. Landed with approx. 2 gallons. I call them killer caps, same as the original cessna ones. All of those guys ripped them out and put the second generation raised caps in. If you talk to the cap guy about this, he just tells you to flip the gasket around and it will be good to go. Kinda hard to do in mid flight and fuel is pissing out,....

Garth

So, interesting thing today. Last week I noticed some stains after of my right Monarch cap. So I cleaned the brownish stains so I could check it. It was obvious something had ran down the wing from the cap. No blue dye. So, I flew for a few hours and it was fine. Then I refueled and flew home. When I got there, there was blue dye all over the top of my wing. When I fuel, I usually bring it up halfway into the cup above the flapper valve. I don't know if this is correct or not for the Monarchs...I've never read one way or another. I've fueled my previous plane this way and this one for a total of 4 years with no problem. But now this one side seems to be siphoning out. Any thoughts? I'm guessing it is just the amount in the cup because my fuel burns are still right on with my JPI. So if this is the case, do I just not fill into the cup? Or do I flip the gasket? Or get a new gasket?

Thanks!

I think mine was about that full the last time I flew and no stain that I could see and my gaskets are ancient. In theory, the gasket should keep any fuel above the flapper from leaking but maybe not. Is it possible your chain interfered some way? If it isn't too hard to flip the gasket, maybe try that(I've never done that) . Also, check the screws that are in the perimeter further out from the cap that hold the bladder to the cap plates

Thanks for the comments Marty. I've had them leak from around the screws a tiny bit but this isn't that. (A quarter turn on those screws fixed that seepage.) This is definitely coming from under the cap at one spot. The dye made it rally clear.

Yeah, I agree. The gasket should keep any fuel in the cup from leaking out...and has for the last year with this plane and for three years on my other 205. These caps are older than those on my old plane so that's why I was wondering about the gasket. But, after getting home and reading this thread again, I'm going to go out and examine the chain and connect point to see if something is interfering.

It looks like the gasket flip should be easy enough. I'm going to do some troubleshooting when I get home in a few days.

Thanks!


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So I ran out to the airport today to inspect the cap and to fly it...first at the current level and then with it filled as I normally do, which is with a half inch to an inch of fuel in the cup above the flapper. The flights were only 15 minutes or so.

As expected, the wing was still clean after the first flight. I then fueled it and flew back to my home airport. Back at the hangar, the wing was still clean, but after I got the ladder out to look at the cap area, I could see just a very thin trace of fuel starting to track out from under the cap. Nowhere near the volume that must have come out the day before to make the mess I found, but it was also an hour and a half flight. So I don't know. I think I'll just keep an eye on it and pay attention to how the chain is laying in the cup when I put it back on. I think I'll also get a spare gasket to carry with me just in case I need it, especially where we are getting ready to leave for Alaska in a few weeks.

Normal refuel level.

Thin trace of fuel.






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