how common are persistent fuel tank leaks?

[ReidVaitor]

When you mention- I have a good Mooney and Cirrus shop I've worked with for years but I haven't begun the process of trying to decide how to get a pre-purchase inspection done on an e-ab airplane

If you?re going to get a prebuy on a RV than you need a qualified RV person doing your inspection, not a cirrus or any other aircraft shop.
If you?re serious about pursuing this, I would encouraged you to pay someone like Vic Syracuse to do that inspection. No offense but none of us have seen the Plane and your description of the history points to the tanks only. I have 700 hours on my plane, no leaks, no maintenance other than my condition inspection. What I?ve read I wouldn?t be happy if my plane was anything near what you described. Why a A&P needs to work on a plane is my first red flag. I would never have anyone touch my plane unless I had no choice, hence my thought that there may be more to this plane than the leaking tanks ( we all agree That may be normal for QB)
In the end don?t settle for anyone but a really experience RV inpspector. If you want to see first hand what I mean- check out the Eaa webinars. Vic did two both pretty much covering the same things that he has seen in inspections. Unless one knows what to look for You are not going to get the respective inspection completed correctly. If all is well (or not) than nothing we tell you will change that fact. Keep on mind you can use anyone other than Vic but I was impressed with his webinar and his name came up this week so I threw him out as an example.
, but it needs to be a qualified RV inspector not some RV folks that built a plane two hangars down from you.
Best of success.

[philip_g]

Here are the log entries that stand out

https://imgur.com/a/Tdr4LwO


Maybe they're minor leaks as you guys say.

Here's a good compression from 2017, the last in the engine log.

https://imgur.com/a/G7z44A3

I thought it was more recent than that, but 79/80 seems a bit suspicious for a mid time engine to me.

[ReidVaitor]

818- is that 30/80 on first cylinder? I don’t see where that was resolved..
Actually I see marvel was used for a stuck valve, which is fine, but nothing to show it resolved the issue with a retest

[philip_g]

Originally Posted by ReidVaitor

818- is that 30/80 on first cylinder? I don’t see where that was resolved..
Actually I see marvel was used for a stuck valve, which is fine, but nothing to show it resolved the issue with a retest

I don't either, but it was 2015 a d approx 300 hours ago, maybe he staked the valve or something. More recent compressions are good. Early this year they were suspiciously good

Here's the page with the whole low compression entry, I clipped it when I screen capped it

https://imgur.com/a/n3m9uGO

He said he'd recheck the compression in 25 hours on the 818 e try and either never did or never made an entry in the engine log

[titanhank]

Originally Posted by Mark33

I did a preemptive strike on my quick-build -7 tanks and sent them off to Paul at Weep No More. He opened up the rear baffles, completely stripped out all of the pro-seal, and re-sealed everything with his special sealant. I?m still in the building process so I haven?t tested the tanks out yet, but I have full confidence that my tanks will be leak free for the life of the airplane. It?s a little bit pricey to have this done, but I guess peace of mind has a certain value.

I need to send him my right tank. Could you elaborate on the cost?

[Mark33]

Originally Posted by titanhank

I need to send him my right tank. Could you elaborate on the cost?

I hate to speak for Paul because his prices may have changed, but he charged me $1200/tank.

[philip_g]

Originally Posted by Mark33

I hate to speak for Paul because his prices may have changed, but he charged me $1200/tank.

That seems pretty reasonable.. too bad it's not really an option for me without repainting the wing

[Mark33]

Originally Posted by philip_g

That seems pretty reasonable.. too bad it's not really an option for me without repainting the wing

Why would you have to repaint the wing(s)? Worst case should/would require the tank(s) to be repainted, but probably not. He may be able to do it without any, or at least minimal paint repair required.

[9GT]

Those log entries state the leaks were fixed with epoxy/cabosil mix. This is NOT how you fix leaking rivets on aluminum fuel tanks. It may fix them for a little while, but that rivet will end up leaking again.

[wilddog]

Paul takes the back off the tanks and that means removing the rivets along the back row. I sent him the paint code and he touched up the new rivets. If you want near perfect paint, tanks will have to be repainted. Otherwise ok from 20?.
Unless you are close enough to deliver your tanks to Paul, shipping to and from is substantial. Paul?s work and business practices are tops.