Over the past three decades, or so, I have heard of cessna fuel bladders being sucked up to the filler cap. But since the invention of new style vented fuel caps, I haven’t heard of this much. Imagine my surprise when I returned from a three hour flight and tried to refuel my right tank and found my bladder staring at me in the filler neck.
We have an older 182L (68’) with long range tanks. We put the Monarch fuel caps on the plane when we bought it back in 2006. We also replaced both bladders in 06’ and 07’. Through the years we struggled with the common problems having to do with the Monarch caps; bad O-rings, cap bottoming out on the tab in the filler neck, venting fuel out the top of the wing ect. But that was all in the early days.
For the last few years everything had settled down and we really haven’t had any fuel issues until about six months ago when our R/H FFC bladder started to leak when more than 30 gallons was put in. This was right in time for our annual. At annual we traced the tell-tell blue stains and determined that our leak was in fact emanating from the bladder and not a loose clamp or nipple. So we pulled the bladder out and found the hole located where the tank would rest up ageist the rear spar. A few days later we installed a new bladder, hoses, clamps drains, and removed and retapped the entire bay. Filler er’ up and no leaks so good to go. Since the annual, we have put around 35 hours on the plane with no evens but the oil change.
Needless to say I am a little mystified with the situation. I have changed half a dozen cessna bladders through the years and and am at a loss for how this might have happened. Tomorrow I will be able to de-fuel the plane and start looking/fixing the situation. To my mind, I would have to of had two separate issues. The first would be a plugged check valve or vent line under the left wing (old Cessna so only one vent). The second would be a defective diaphragm in my R/H gas cap.
Looking for anyone who may have had a similar situation and what you found. Also any other imput or advise is welcome. Thanks!

Yep.

I measured the location of the vent per the service bulletin, and it was slightly too high behind the cuff.

I moved it down to the recommended location, and it happened again a few flights later.

So I moved it down 1/4" (just outside the recommended location) and have not had a problem since.

My arm was getting tired trying to get the tank clips reattached with a cow checker sleeve on. I'm glad it was fixed.

Good luck.

Thanks for the reply Lesuther,
I gather from your post; the only thing you found wrong was the vent line out of position? Were you running with vented fuel caps at the time?
I have been through the Cessna Pilots Association paper regarding the vent line placement. I have always followed the vent line advise and have never had a problem. Maybe it slipped out of position.
JJ

So I moved it down 1/4" (just outside the recommended location) and have not had a problem since.

Curious if it is low enough to pick up ice at the lower position. If so, it wouldn't be any better than my trouble free snorkle vent out the top of the cabin.

I'm sure it could be exposed to ice, meteorites, aliens, or other things I'll never fly in proximity to for any intentional duration.

After working on the plane the past couple of days, I am as mystified as ever. My original suspension was that I would find a blocked vent line from a mud dauber, wasp, or other critter. But after removing the line and inspecting it as well as the section through the bladder tank and check valve, nothing was found. So I moved on to the inter-tank vent line. Nothing there either, air moves back and forth with ease.
The only problem I found was with the Monarch cap that was on the same bladder tank that collapsed. The little diaphragm valve seems to have taken a set. The cap will allow air to escape but not enter the tank. I placed a call to Hartwig to see if there was a fix for the diaphragm. There isn’t. So I’m looking for opinions on switching caps to a better design. Are the Cesssna vented caps the best option out there? And can they be disassembled and worked on if the need ever arises down the road?

Good find.

I'll check mine now to see if I had the same issue. Perhaps I've just been pressurizing enough to overcome the lack of proper cap venting. Less than ideal. I just blew on mine, and heard the baffles rattle, and assumed they were fine.

Mine appear to be Cessna caps and cannot be disassembled except by drilling the rivets. Might be worth it for me to check though if they might be blocked.