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Dry to the touch- not sure if its old. Bottom side of wet wing on 1979 Skywagon
How big of a deal to fix?
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Dry to the touch- not sure if its old. Bottom side of wet wing on 1979 Skywagon
How big of a deal to fix?
What's the owner/seller got to say about the stain? History of leak-leaks more with full fuel load above-in flight (rough air?) or sitting? Stuff like that.
Edit: Watch out for "they all do it".
Gary
Last edited by BC12D-4-85; 03-11-2023 at 01:09 AM.
It probably hasn’t been addressed, or the mechanic would have cleaned up the fuel stains. As Gary noted on your other thread, ask a mechanic who works on these fuel systems.
From this pilots perspective, NO fuel leaks are acceptable, and need to be fixed.
MTV
Isn’t it the same “fuel system” as any wet wing cessna? Aren’t virtually all single piston
Cessna’s since 1979 wet wing? If so- wouldn’t basically any GA mx shop be familiar with this fuel system?
Nope, because not all shops work on all aircraft types, for one thing. And not all mechanics are widely experienced. You’re assuming every mechanic has a broad and comprehensive experience base. Not necessarily the case.Originally Posted by Cardiff Kook
And, some shops “specialize” on one or another type, and even specific repairs.
MTV
There are a number of wet wing specialists around the country but this should not be beyond most shops/mechanics. It will be a lot of work to address correctly but not a technically difficult job. I've frankly had more trouble in getting the top access panels to seal up than lower rivet leaks.
My approach for rivet leaks is to access the inside as much needed (don't be shy), clean all sealant from around the leaking rivet tail from about the mid way point between any adjoining rivets. I am a believer in re-setting the rivet with a gun/bar to be sure it is not starting to work. It seems to prevent a recurring leak (especially in Mooney's). Clean it some more and apply the sealant exactly per the instructions and create the environment needed per the instructions. Temp range important for mast sealants and cure time really needs to be followed for full cure before fueling.
Some sealants have adhesion primers available that are not generally in the manual, they are really toxic but really work well. The worst part of the job is the removal and clean-up. getting all the sealant chunks and flakes out of the tank sucks, an air siphon vacuum is a life saver and are not expensive. The aft edge requires long arms mounted to young bodies and a lot of the job is by feel but it is doable.
The pic looks like the neighbor rivet might be getting some color as well. You would likely find there is fuel under the paint around the rivet head, until the paint cracks it doesn't leak much. Like anything else on a plane, wet wings can give trouble but it isn't a regular sort of event here in the shop.
Just more free advice that may be not worth the price.
Ken
Great catch!! I had to go back to the picture as I only saw the really bad one.
There is a fuel stain on all three rivets in that row when I expanded the photo. Could there be an aft spar issue causing a twist or movement to create the leaks?
Serious hypothetical thought there from me on very limited knowledge- but wanting to learn.
I don't know where you've been me lad, but I see you won first Prize!
Crap. I see the bigger stain now. Amazing I didnt even notice in person
I’d bet what can be cleaned off already has been. Some stains are permanent.
The "halo" stain circling the rivets may be permanent. What does the owner/seller have to say about this issue? Most anything can be fixed for the right price.
Gary
I rubbed on it for a few seconds with my finger- it was on there and i couldnt get it to smudge. May have been under paint?
I will call to get more details.
When I mentioned it he said it had appeared “sometime in the last year.” He didnt think it was a big deal to address so the conversation moved on.
Ok. You know what to do next.
Gary
That might be an indication of the care/attention that plane has received. Or not. But a fuel leak like that needs to be fixed.
MTV
Here is what the Cessna service manual has to say on leaks
Leak can be fixed but that stain will be there till you repaint it. If I had to build a story like a detective I would guess that the leak is a decade old and the owner just lived with it. Would make me wonder what else he lived with or how long he let the oilchanges slide. It's all reciprocal and a planes real condition is only as good as the owner/maintainers anal tendencies. Of course supply and demand dictate what we have to work with.
My guess is the owner never saw a drip. If it ain’t broke, don’t fix it.
ak49flyer liked this post
Reasonable to ask seller to fix it? I told him anything having to do with airworthiness i want fixed. Seems gray as to whether its airworthiness issue per cessna manual if its not actually dripping.
If he doesn't fix it, you should. I'm not a mechanic, but I wouldn't let that slide on an inspection. One thing about leaks: They rarely fix themselves, and they often get worse. The fact that a neighbor rivet also has stains also suggests this may be bigger than you think.
MTV
Perfectly safe and legal to operate as-is, per Cessna and the FAA. Current owner probably doesn’t make mountains out of molehills and uses the airplane for the tool that it is. Should it be fixed? Sure, at some convenient point. Should it be an issue at the sale? Not if everything else checks out, and/or price is right. Of all the things I’d be concerned about on a 180/185 purchase, this is way down the list…
Yeah,common issue and probably not going to spring a major leak but it does have some paint damage. Pricing accordingly would be appropriate.
You really need to find a shop that can do the repair and ask what the price is going to be. It could be several grand, you want to take that into account if you plan to buy. It would not be a sale stopper for me by any means because you know about it and it can be fixed. I would keep digging hard before you commit. DENNY
Cardiff, I did some reading about wet wing repair. Here’s an article that may help you understand the tanks better. Scroll down for the tank story.
https://www.tennesseeaircraft.net/20...-more-is-less/
This link may give some insight into integral fuel tank leaks. The second video of the Mooney leaks puts the Op's problem into perspective.
https://nslaerospace.com/aviation-fu...to-the-basics/
"That's not a leak THIS is a leak"
The above posts bring up a good point. Drain the tank and take a look inside. Do you have previous attempts to fix it with some tank seal? that would suggest a much bigger project down the road. DENNY
I've not worked on a wet wing 185. Is there an access panel above the area of those leaky rivets? If so, it should be relatively easy to open that panel to clean off and apply some sealant to those leaky rivets. I see two leaky rivets which at one time made a big mess which has been cleaned off. Notice there is a large stained area of paint covering most of your photo. Look above that top rivet. See the light stain in the paint.
Dry to the touch- not sure if its old. Bottom side of wet wing on 1979 Skywagon
How big of a deal to fix?
Can you post a picture of the top of the wing in this area? This will suggest how to open the tank for repairs. I wouldn't let this keep me from the plane if all else meets your requirements.
NX1PA
Pete,
The only access is to remove the access port surrounding the filler neck. Not very close to this, you’ll want a long, thin arm.
THE 1985 185 I picked up new passed white fibers, which were caught in the screen and the injectors. We searched those tanks a dozen times looking for…..something, with no success. Long reach, big angles, and dark. Eventually, the stuff stopped passing.
Years later, I met a guy who worked at Cessna in those days. Asked him the question: what was the stuff. He said they used white cotton rags to apply and smooth the tank sealer. Apparently, someone fudged their rag count. It was impossible to see even that in that tank, and some very good mechanics tried, as did I.
I hope to never have to muck about in one of those tanks again.
If you’re working in one of those tanks, account for all your rags.
MTV
Last edited by mvivion; 03-13-2023 at 12:58 PM.
Here are a couple of pic's of a wet wing. You can see the oval access panels in the top skin. When I bought my 180K with wet wing, the guy said they had to drill and remove the top skin to really do a good job of resealing. I think the wet wing design is great for being simple compared to a bladder if the sealant works. That's a big "if".
They had to replace a wing!
Seems a great place to install more access panels on the back side. Extra goop to seal the screw holes.When I bought my 180K with wet wing, the guy said they had to drill and remove the top skin to really do a good job of resealing.
Yes, it the lower ones will probably leak every 5 years, but like many parts you would remove, clean really well, put new sealant on and reattach.
My guess as a non-A/P is that getting approval for that, even using Cessna parts, would take an act of congress these days.
I don't know where you've been me lad, but I see you won first Prize!
The back wall of the tank is the rear wing spar so probably don't want to change that. Here is one more pic that shows how the newer 182's have access panels for each wing bay on the under side that my 180K does not have. In reality it wouldn't be a big deal to make more access holes in the older wet wings on the bottom side assuming the doublers maintain the strength of the original wing skin.Seems a great place to install more access panels on the back side.
I bought several new 180 and 185s in the middle 70s. Each of them had those white fibers on the fuel strainer screen on the first inspection only. Never to return and never found them elsewhere.
NX1PA
I did not say it well. Top skin, over the aft area of the tank was my thought. Essentially behind the original ones near the rear spar. Makes it easier to reach, inspect, repair...The back wall of the tank is the rear wing spar so probably don't want to change that. Here is one more pic that shows how the newer 182's have access panels for each wing bay on the under side that my 180K does not have. In reality it wouldn't be a big deal to make more access holes in the older wet wings on the bottom side assuming the doublers maintain the strength of the original wing skin.
I don't know where you've been me lad, but I see you won first Prize!
I thought of that after I responded. It does seem a fore and aft access cover for each bay, both on top and bottom, of the wing would make sealing so much easier and better than drilling and removing the top wing skin.I did not say it well. Top skin, over the aft area of the tank was my thought.
They chose to replace the wing. I think his summary about maintenance costs on old airframes is interesting. I also found his comment about well-applied sealants lasting for 40 years is worth considering. How old is that 185?
Sometimes the old stuff serves us better. Bladders are easy enough to replace. And flexible so not compromised by airframe flex, plus less prone to rupture if a wing gets bent. I considered using a bladder in my Cub wings. I still think it may be a good project to try.
I've heard a lot of reports of leaking wet wings on later model Cessna's.
One later model 182 on my airport has had the tank(s) resealed more than once.
Makes me glad the early 180's like mine had bladders--
yeah, they go bad, but are if not easy at least relatively straight-forward to replace.
Cessna Skywagon-- accept no substitute!
I've seen the lower skins of a C-185 move or drum some in flight. Heavy fuel and on floats. Not sure why, but the floats tend to change the airframe's vibration nodes so the wings get a focus. If there's movement of the lower skin I suppose the rivets can get stressed.
For example locally there's a couple of Cessna's with the winter's 30#/sq ft total snow load. The wings are twisted aft behind the strut with the ailerons bent down, and the lower skins on the C-150's are well wrinkled around the rivets.
Gary
This one went on for the first 150 - 200 hours, then stopped. The gent I spoke with was pretty sure someone left an entire rag in one tank. He said a little "fuzz" was "normal", but not that long.
I got really good at landing out somewhere, pulling the top cowl, finding the plugged injector, removing, cleaning and replacing, then continuing with the flight. I have no idea how many times I did that, but it was a lot.
Our mechanics tried really hard and long to find the source of that stuff with no luck. They drained fuel, and got in there with light and mirrors, but all you could see in there was black mung. I spent a few hours searching, and trying to probe suspicious "lumps" in the sealant, with no luck. It is REALLY hard to reach all parts of those big flat tanks.
MTV
Last edited by mvivion; 03-13-2023 at 01:04 PM.
So.... Did you buy it?
A solid rivet properly driven in the correct size hole will seal without needing a sealant. I would expose the shop heads in that row and hit them again with a gun and bucking bar…they may have just been under-driven. Do not apply sealant until you leak check them. After you are sure that the rivets sealed, then you can pro seal the shop heads/seams, and wait 24hrs at room temp (70) to cure. If you think these are hard to get to, wait until you get to change a flap rail.
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