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how common are persistent fuel tank leaks?

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philip_g

Well Known Member
maybe a stupid question, but I'm looking at the logs on a completed and flying 10 that is for sale, and it seems like every year or two since new, the builder has had to chase fuel leaks in both wing tanks. coming from mooneys, that's usually a sign that the tank seals are failing and need to be redone to the tune of about 15k. on the mooney, once they're redone they're good for a couple decades and don't leak usually unless something like a gasket at the base of the tank where the fuel senders sit fails. most puzzling is pretty recently an a&p went in and patched some for them in the left tank this year, the left seems the most troublesome for them.

I guess I'm asking if the tanks just weren't sealed well during construction, or if it's just something that happens periodically and that is just a minor annoyance to be dealt with. and if it is abnormal, is it a major hassle or even possible to at some point just remove the tanks and completely reseal them or is it something that you have to take the plane to someone like weep no more in MN like you would a mooney that has the tools to get in there and seal them in place?
 
philip_g said:
maybe a stupid question, but I'm looking at the logs on a completed and flying 10 that is for sale, and it seems like every year or two since new, the builder has had to chase fuel leaks in both wing tanks. coming from mooneys, that's usually a sign that the tank seals are failing and need to be redone to the tune of about 15k. on the mooney, once they're redone they're good for a couple decades and don't leak usually unless something like a gasket at the base of the tank where the fuel senders sit fails. most puzzling is pretty recently an a&p went in and patched some for them in the left tank this year, the left seems the most troublesome for them.

I guess I'm asking if the tanks just weren't sealed well during construction, or if it's just something that happens periodically and that is just a minor annoyance to be dealt with. and if it is abnormal, is it a major hassle or even possible to at some point just remove the tanks and completely reseal them or is it something that you have to take the plane to someone like weep no more in MN like you would a mooney that has the tools to get in there and seal them in place?
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I suspect your assumption about the tank build quality is accurate. No it isn?t normal.

1. If the tanks has defects, are there other issues with the build you havent found yet? I would do an extremely detailed pre-buy by somebody very familiar will the typical issues.

2. The tanks can be fixed. Cutting a hole in the back baffle so that you can re-applying proseal correctly. You then will have to seal your new access panel. You can also see the weeping rivets with a little green loctite and a small vacuum, but that will trash your paint job.


It?s doable, is the rest of the aircraft in a quality state that you want to go through the expense and effort with the tanks?
 
If slow build tanks, it depends on how they were built.

There is a lot of bad advice on this forum about easier ways to build the tanks. If the builder disregarded the bad advice and followed the instructions, they probably won't leak.

The problem is that the tanks will hold pressure and paint blisters won't show up for a a few years later.
 
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Thanks for the insight Bob, I guess you kind of read into my thoughts and concerns without me having to say them.

I haven't seen the plane yet, I have to fly down to see it about 3 hours each way, so I'm just reviewing the logs. The builder appears to have kept and flown the airplane 1k hours in 10 years and kept pretty detailed logs so that's a good sign. But my concerns are the same as yours I think.

It's priced I believe fairly low.


It's listed by a broker, while still registered to the builder. I'm not sure if maybe the builder passed away or something along those lines but that's odd to me. Builder repairs the entire life of the airframe and recent a&p repairs could indicate that's the case, unfortunately. Also the plane is adsb out and hasn't flown in 6 months according to flight aware.


Doesn't appear to be a vaf member, not a deal breaker but a real bummer.


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. I'd want a good borescope done, the history indicates low compression on one jug and a suspected sticky valve some time ago and now magically at the last condition inspection probably done at the request of the broker the compression looks really good across the board. Builder ran a quart of MMO in the sump at every change. Not sure how I feel about that.
 
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N941WR said:
If slow build tanks, it depends on how they were built.

There is a lot of bad advice on this forum about easier ways to build the tanks. If the builder disregarded the bad advice and followed the instructions, they probably won't leak.

The problem is that the tanks will hold pressure and paint blisters won't show up for a a few years later.
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Can't tell if it was a QB or a sb from the logs. Wonder if vans would be able to tell me from the serial number.
If memory serves the plane first flew in 09 so they've had lots of time to show up.

Guess I'm a bit twitchy about leaky tanks from owning mooneys where it's kind of a big deal to have them stripped and resealed, I mean, it's not really a tank it's the wing on the Mooney so kind of a different beast as near as I can tell.
 
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That's not what Van's says

rleffler said:
I suspect your assumption about the tank build quality is accurate. No it isn’t normal.
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When I thought that Van's might repair my Quick build tanks that have leaked incessantly due to poor quality work-manship, Sterling Langrell wrote this in an email to me:

"I did receive the pictures and have been looking over them and discussed this with my boss. The location of the leaking rivets is a place we have seen from time to time as it is a location that can potentially get some foot traffic being right next to the wing walk area, sitting or walking on sealed rivets can cause the seal to fail. Given that this is a second hand kit paired with the age of it I am not able to offer a "warrantee" repair on this tank.

We have had similar leaks on our factory 10 caused by people stepping and sitting on this area. We have had luck with sanding the paint away and applying a thin dime size dollop of tank sealant on the exterior. There will be a small amount of buildup on the outside but the tank sealant can be painted and is not very noticeable in the end"
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So fuel tanks leaks on the top rivets should be expected. You be the judge if you want to repair rivet leaks with a "dollop" of tank sealant. BTW, the original builder of my plane told me that the QB tanks leaked "like a sieve" from the very beginning. I have no reason to dis-believe him after the stories I've read from other QB builders.

-Marc
 
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Preemptive strike on fuel tanks

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.
 
philip_g said:
...
Guess I'm a bit twitchy about leaky tanks from owning mooneys where it's kind of a big deal to have them stripped and resealed, I mean, it's not really a tank it's the wing on the Mooney so kind of a different beast as near as I can tell.
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The good thing about an RV is the tanks are just bolted and screwed in, similar to a Cherokee. However, there is a good chance the paint will get messed up.

One solution is to turn off the fuel, drain the tank, put a vacuum on the tank via the vent line, and put some green wicking loctite on it. That may seal leaking rivets.

Plummit said:
...
BTW, the original builder of my plane told me that the QB tanks leaked "like a sieve" from the very beginning. I have no reason to dis-believe him after the stories I've read from other QB builders.

-Marc
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Why didn't the original builder pressure test the tanks and fix the leaks before putting them in service, is what I would want to know.
 
10 tank leaks

Just because there are persistant tank leaks being repaired, I wouldn't automatically assume the rest of the build is questionable. It depends of which rivets were leaking.

The RV-10 tanks are the only ones in the fleet (I think) that have stiffeners on the inboard bay. It doesn't matter if they were built perfectly, because if you sit or step on them enough, you WILL break the seal on the end rivets on the stiffeners. **Ask me how I know:mad:. **

There are four stiffeners in the inboard bay. The forward is significant because it is the tank attach point. The third back from the front is a J-channel that runs the length of the tank. It is the unsupported end of the J-channel and the other two that are the problem. They are attached to the skin only and will flex everytime you put any pressure on them. Eventually, you will break loose the proseal on the end rivets of these stiffeners. Green locktite will not keep these from leaking- been there, done that. The only thing that will is NEVER allow anyone to step forward of the wing spar- good luck with that.

It would have be nice if Vans had connected these three stiffener ends to the rib but that is another story.

**(I've had both tanks off at least once to repair these leaks and the last time I made a modification that tied them to the rib- one year later--no leaks)
 
It?s the small things

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.
 
Compression?

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
 
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ReidVaitor said:
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
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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
 
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Mark33 said:
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.
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I need to send him my right tank. Could you elaborate on the cost?
 
philip_g said:
That seems pretty reasonable.. too bad it's not really an option for me without repainting the wing
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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.
 
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.
 
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.
 
wilddog said:
......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.
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I used Yellow freight and shipped from south Texas and it only cost me a little over $100 each way. To get this good price you have to use their online/self help feature and delivered the package yourself to their nearest terminal dock. It?s WAY more expensive if you call them and have them set everything up for you.
 
wilddog said:
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.
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Paul did one of our Mooney's. Wilmar is a 4 hour flight
 
Mark33 said:
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.
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I assumed with blending there would be a good portion of it needing paint.
 
philip_g said:
I assumed with blending there would be a good portion of it needing paint.
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I?d give Paul a call and talk to him about your concerns and then make your decision from there. Paul is a top-notch guy and I?m sure he?d do everything possible to minimize any damage to the paint.
 
Mark33 said:
I’d give Paul a call and talk to him about your concerns and then make your decision from there. Paul is a top-notch guy and I’m sure he’d do everything possible to minimize any damage to the paint.
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Since I haven't seen the plane yet I can't even really speak intelligently to it, I can't visualize how it goes together or where it has been leaking from. If he has been fixing leaking rivets improperly that might explain why it's been an ongoing problem.
I might fly my Cirrus down Monday night and see it, debating if it's worth the money it will cost me to fly there and back still. I can't go commercial and save the money unfortunately. I'm hoping if I see it I can see some staining and see exactly where it's been weeping

If Paul charges 3k or so and not 15k like the Mooney I'm less concerned about it but still concerned about the plane overall
 
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