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I've used the Ultrawingwalk to do patches on mine and it works great. It's also locally removable if you get a screw leaking or something, and can then patch back over it with the same stuff.

With the recent discussion of wet wings, and Mooney wet wings at that, I was curious what the real world experience has been with wet wings. My aircraft had almost a quarter century on the wet wing sealant before I started to see leaks. I wound up having the tanks stripped and resealed at the 25 year mark not because I had to, but rather I was planning on having the aircraft painted and wanted to get this squared away before repaint (and to "reset the clock" as it were). There's still a part of me that knows that I did a reseal more prematurely than I could have, and I suspect that I could have gotten another 5 years as is, and with a quality patch job maybe even more... Here is the worst of the seeps/leaks under wing at year 24...for life in a caustic environment, this is pretty solid performance in my mind! I flew like this for 2 years, and when the tanks were resealed, the area was cleaned and today you can't even see where the leaks were...no damage to the underlying paint from the leak.

Pulling off the inspection panels I saw no previous patches, surprising considering the age. Will try to patch it but will stick with the wet tank and get on the schedule at Ft. Lauderdale for a strip and reseal. It just looks too good as it is. Thanks for everyone’s input!

Has anyone ever noticed a big difference when they opened tanks to patch or reseal with regards to the top wing sealant and the bottom wing sealant? It seems there are two possible reasons that sealant covered in fuel would help protect sealant...better thermal regulation with the large volume of fluid that could absorb heat, and keeping the sealant wet to keep it from drying out. If the offered theory is that fuel is so damaging to the sealant, then it seems to reason that keeping tanks empty would be better...but I've never heard anyone suggest this... Not sure if any studies have been done on either theory, or if keeping wet tanks full is just an OWT/tradition for "best practice" rather than actual science??

I had my 2000 Bravo resealed by Weep no More in 2019 since it had gone through multiple patch jobs, was leaking minimally, but I wanted to get it painted, think the cost was $11k, no leaks since, I kept the tanks filled to the brim whenever I can, the sealant dries out when the tanks sit empty in high ambient temp, brittle sealant cracks under hard landings on old and hard donuts, I put the Bravo on jacks whenever I do not fly it for more than a week, short bodies were almost 900 lb lighter than a long body fully fueled, donuts still the same

Tri-Flow is recommended for some of the Mooney lube points, so something worth having on hand. It also includes Teflon, and probably works well for the Bendix gear. Again, that is a patch, and eventually you will get tired of climbing out and lubing the starter, and one day it may not work anymore.

Mine went 44 years on the original seal. Just patched two minor seeps this year's annual. No leaks since patch, but question 2 didn't have that option.

@Vance Harral Thanks. Good to know it's only a $10,000 problem; I thought I'd read in a post that one of the other sealing guys was running $7K-$8K per side! Thankfully, I've spent less than $1000 on the two patch/repairs over the last 7 years. Don't have any blue/brown stains to clean up. I'm pretty happy continuing with this strategy until it isn't! With as old as my sealant is (54 years??), G100UL is a HUGE concern for me...it may result in my current strategy ending. Which will piss me off, greatly...and, no doubt, I'll be told, "it wasn't G100UL it was your old sealant!"

No criticism of your strategy, we also paid $1-2K for patches every few years, for the last 20 years, and it served us well. That said, your estimate for a reseal is pessimistic by more than $5K. After about 50 years of original sealant plus patches, we decided to bite the bullet, and have an appointment with Don Maxwell at the beginning of February for a full strip and reseal on our M20F with 64 gallon tanks (roughly the same vintage as yours, I recall). The contracted price is $9600 for both sides. 7 year warranty, for what that's worth. The $9600 quote doesn't include travel costs. Round trip from Denver to Longview in the Mooney will put about 8 hours on the airplane, but it's hard to say whether that should be included in the accounting or not, as we like to fly and would likely have gone somewhere else instead. Short-notice round trip airfare from Longview home, then back for pickup, adds about $750 (anyone traveling from northeast Texas to Denver around the end of January, and/or in the other direction around end of February?) I don't know whether to feel better or worse that we scheduled this reseal right before the recent news about G100UL and Mooney tanks. No G100UL in Colorado for now, but it's obviously a strategic concern. We're unconvinced bladders are a better bet on that front, and slightly prefer wet wings for other reasons as well. The other alternative was to do nothing, but we had reached a point where we were concerned the airplane might spring a significant leak that would make it difficult to deliver it even to a shop that would patch it. You also just get tired of looking at the ugly blue/brown stains after a while. Even when it's not a safety of flight issue, it starts to feel like you're neglecting the airplane and creating a major sticking point for sale somewhere down the road.

Nope. Never found anyone in SOCAL willing to do the work. Was lucky to have my first mechanic patch them. I had an appointment with weep no more last Oct but missed it due to a mechanical issue enroute to MN. Plane ended up stuck in AZ for a month waiting on parts.

Did you ever have the tanks stripped and resealed? Are you still on original base sealant? Seems like part of the issue that's uncovered with wet wings is that at a certain point you can just patch and kick the can down the road, but sealant surely has a finite life span. At a certain point it seems that the solution is a strip and reseal rather than patching, I think. Perhaps that time frame is 30 years? More? Good luck with the bladders; I hope the install goes smoothly!

I didn't really know how to answer this. Near as I can tell from the lack of log book entries, my tanks have the original sealant from 54 years ago. I have no idea how many time the tanks may have been patched before I purchased my plane roughly 7 years ago (nothing I saw in the logs but, who knows). I have had NO leaks in the left tank. I started to get a small seep in the right tank after about 2 years of ownership. I had it patched. About three years ago the right tank developed another seep (different place) and I had it patched. No problems since then. At this rate, I have no issue with continuing to patch vs. a $15,000+ reseal.

The intent was to see how long on average does the Mooney wet wing last before needing sealant maintenance; and for standard tank maintenance (either reseal or patch) how long before seeing further issues that need to be addressed? i.e. if Mooney wet wings are failing 3 years off the line vs 30. Things like a leaking gasket from a fuel sender that's over-tightened aren't sealant related and don't reflect sealant compromise. So I wouldn't count that as sealant failure, If that makes sense.

That AOPA Baron except for a bladder leak in a 50 year old patched bladder that leaked at the patch, some before G100UL, seems to being doing just fine. I'm betting it has a lot of nitrile in it too. Now with a new bladder we can watch.

I’ve patched several tanks, every time I patched the materials used were identical to the original sealant. A patch therefore shouldn’t be any weaker or more susceptible to solvent attack than the rest of the tank, if anything as it’s new sealant it ought to be better? If a patch worked for a significant time with any fuel, it should work for any fuel if you change fuels? Every issue with patches I’ve seen were basically from inadequate prep, whether from not digging out enough of the old, or making sure the old was completely clean (I was patching turbine tanks and Jet is oily), or old out of date sealant. If your sealant is old it may not ever cure correctly, cold temps can cause the same thing, if your mixing from cans it may be prudent to mix a test batch the day before, and keep some from your patch so you can be sure it cures completely.

Did you remove all the old sealant and put in new? Or did you just patch leaks?

Not worth it to me to see my hanger truss in m paint. I wouldn't pay 5 grand for it. You had a big patch of your wing done so Based on your self described OCD Iit appears you are in. Enjoy your reflections. Scott

I think it’s important for every one to know their limitations. I know that if I do it I will mess up somewhere, and that defect, while probably invisible for everyone else, will bother me every single time. OCD, I guess… so I’ll let someone else mess it up, and then *I* won’t notice it! More seriously though, just applying a protectant won’t do it for my plane. The difference between the patch that the guy buffed out professionally and the rest of the paint is quite clear. The reflections are way more obvious. So the fading, oxidation, and dirt have to come out before any other coating will be applied. And I’m not doing it for the reasons mentioned above. Here is a picture showing the difference. Notice how easily you can see the hangar truss reflecting in the polished area, but not in the surrounding parts

I have this experience with more than one Lycoming. Shooting lube into the bendix gear works, but is quickly a patch and not a repair. Generally, I think that confirm the problem is the Bendix gear and not truly the starter itself. You can choose to remove the starter and rebuild the Bendix gear portion. If your labor is low cost (owner assist options) this is a viable option. If you are paying full cost for labor, then it is probably penny wise and pound foolish to just rebuild the Bendix Gear. Example of the repair:

Hello Andrei, See if you can get a test patch done from the guy who travels. Have him explain his process then you can make a decision based off of seeing and hearing the processes of both. David

Okay, I've narrowed things down to two choices. One option is to go to a guy who is highly recommended in Green Bay. Works in his own large heated hangar, it is a well-established business which mostly does bizjets but wants to get more customers by penetrating into the smaller planes market. Recommended by my mechanic. But it is quite expensive -- 5 AMU for doing the whole plane with some fancy ceramic coating which should last 5 years +. This guy seemed to know what he is doing, he explained to me all the details of what he would do, did a test patch which came out very nice, etc. The other choice is a mobile guy recommended by the mechanics at Poplar Grove. He travels for these jobs in his C150, and works in your own hangar. I don't know what kind of polishing he would do, and what kind of ceramic coating he uses. The Poplar Grove people said they had seen some of his work and that it was good, but that's all I know. 1.5-1.8 AMU. Since my hangar is not heated it'll have to wait until April or May. What would you guys choose? Really could use some help deciding... Thanks.

I think it all depends on the age of the original sealant. Problem with patching is trying to find the leak, remove bad material and prep, and then patch. If more sealant is placed over old sealant then when that material contracts sometimes it puts more tension on the bad sealant and makes a leak worse. But you can't beat the efficiency of a wet wing...with a bladder you give up fuel capacity and give up useful load. And bladder material also has a finite lifespan as well. Most estimates I've seen say a bladder should last 20+ years...which is similar to well applied sealant that is care for by hangar/leaving fuel in the tank. So the big question is the overall condition and age of your sealant. By the time you hit 25-30 years, it's probably a good time to start thinking of a reseal if you develop significant leaks. There are a few shops who take the time to locate leaks, and prep/patch correctly. But in the hands of someone not experienced, you may kick the can down the road to more issues in the future and given it's more labor than product you typically spend at least an AMU or so for patch work.

This was posted by Jet Driven and shows why no amount of testing of ANY fuel will cover all the possible issues that result in leaks. "We do patch wing tank fuel leaks occasionally. You'd be surprised the crap we see. People use non-approved sealants, or they dont mix the approved sealant properly. They dont prep the work, they dont find the leak, they smear it with their gloved fingers. We recently fixed a wing tank that the client paid amost 3K to a well known east coast MSC. The sealant was light gray and it was gooey like putty, it was the wrong stuff, not mixed right, or both. The tank was leaking again after half a year. We've got a 177 Cardinal in our shop right now actually, it was leaking from the outboard corner of the wing tank, the owner is working with us on this, he pulled the top cover off, was sealed with orange RTV and it was gooey and smearing off because it's not supposed to be there, the end board corner of the tank had at least two different kinds of crap smeared all over it, and it was leaking underneath that. After spending the better part of two days, stripping and scraping and stripping and scraping, it's cleaned up enough where we can probably put sealant on it now. Point being, sometimes properly and accurately fixing a wet tank Mooney leak can get very expensive. One client just paid nearly 30 grand to get his 100 gallon tanks stripped and resealed. Prayer is not a strategy. I'm not saying take your plane to O&N and have bladders put in it, but I would say that if the plane has bladders and they're not leaking, that is one $20-$30,000 repair job you're probably not gonna have to ever worry about.

They aren't quite the bad. The OSHA limit for Carbon Monoxide exposure if 50 PPM for 8 hours per day. A rule of thumb for 24 hour exposure (no rest/recovery) is 1/10th, so 5 PPM. American Council of Governmental Industrial Hygienists (consensus) standard is 25 PPM for 8 hours. Short term limit (15 minutes) is 200 PPM. That said, I know of a warehouse with poorly tuned propane forklifts that was running over 240 PPM, at sea level. And most standards take into account normal workplace altitudes, but we fly above those. I would not be concerned with 5 PPM in the cockpit, but would have it addressed once I was on the ground. 25 would trigger to me do something now. This is my WAG from some 40 years doing occupational health and safety and it not intended to direct your response. The problem with the Dead Stop is that the color change is subtle. And most people mount them out of line of sight. So even if it did change color, you probably would not notice. When Aviation Consumer tested. here is what they said. "Having seen these in dozens of aircraft, nary a one darkened, we assumed they were nothing more than a feel-good gimmick, albeit a cheap one. Thats hardly the case, however. When exposed to CO in our test device, the Dead Stop turned noticeably darker after about five minutes of exposure at around 125 PPM, a low to mid-level of CO. At 500 and above, the patch darkens fast enough to watch, turning pitch black." Sorry, but 5 minutes at 125 PPM, IMO, is too slow for a change you might not see across the cockpit. Pitch black at 500 PPM, at altitude, you may not ever see as you will be marginally functional. The level where CO is considered Immediately Dangerous to Life and Health is 1200 PPM. At half that at altitude, you WILL be impaired.

Bladders add 37-40 pounds, but they effectively end the risk of future fuel leaks. Plenty of airplanes on here lamenting fuel leaks, but none lamenting bladders leaking. Theyre made of really thick rubber, about 3/16". and theyre durable. We just did a set of fuel bladders for a PA30 Twin Comanche. The bladders in these are very thin and flexible. About 1/32" thick. But guess what, 3 of the 4 were original 1969. One was leaking a little, so we did the whole set. I had the 10 gallon add on kit added to my plane a couple years ago. This requires removing the outboard bladder and gluing a nipple onto it to connect to the new bladder. Still supple, still great condition. It was installed in 1992. So I guess were good for a while. We do patch wing tank fuel leaks occasionally. You'd be surprised the crap we see. People use non-approved sealants, or they dont mix the approved sealant properly. They dont prep the work, they dont find the leak, they smear it with their gloved fingers. We recently fixed a wing tank that the client paid amost 3K to a well known east coast MSC. The sealant was light gray and it was gooey like putty, it was the wrong stuff, not mixed right, or both. The tank was leaking again after half a year. We've got a 177 Cardinal in our shop right now actually, it was leaking from the outboard corner of the wing tank, the owner is working with us on this, he pulled the top cover off, was sealed with orange RTV and it was gooey and smearing off because it's not supposed to be there, the end board corner of the tank had at least two different kinds of crap smeared all over it, and it was leaking underneath that. After spending the better part of two days, stripping and scraping and stripping and scraping, it's cleaned up enough where we can probably put sealant on it now. Point being, sometimes properly and accurately fixing a wet tank Mooney leak can get very expensive. One client just paid nearly 30 grand to get his 100 gallon tanks stripped and resealed. Prayer is not a strategy. I'm not saying take your plane to O&N and have bladders put in it, but I would say that if the plane has bladders and they're not leaking, that is one $20-$30,000 repair job you're probably not gonna have to ever worry about.