Fuel Tank Poll

[mooniac15u]

Just now, teejayevans said:

Lets see, we have water, avgas AND whatever additives they use these days, don't know if EU fuel has different additives than USA.

It's just hydrocarbons and tetraethyl lead.

[AH-1 Cobra Pilot]

Nothing is ever 100% pure.  Your avgas contains trace amounts, (or more), of water; we all know that.  It also contains very small amounts of acids, salts, etc.  Over time, these can build up on surfaces inside your tank, react with the water, and very slowly do damage.

BTW, do you know the FDA limits on rodent feces in your corn flakes?  Do you want to know?

[mooniac15u]

6 minutes ago, teejayevans said:

The pictures in his other thread about the refit shows the corrosion on the bottom, which makes me think it was water resting on the bottom.

After looking at those pictures and rereading his comment here it seems that it was filiform corrosion which is a very specific process that occurs in a small space between metal and an organic coating layer.  I believe it starts with water getting into the crevice and probably requires some kind of electrolyte to initiate.  In this case it was probably forming under the sealant.

[mooniac15u]

Just now, Hyett6420 said:

Yes it was.  The sealant was bubbling nicely allowing the fuel to escape.  

That sounds like it could be pretty tough to spot under a layer of sealant.  Do you happen to have any pictures of what it looked like in those areas before the sealant was removed?  On surface coatings like paint it is easy to spot the wormlike lines.  I wonder if there is a similar characteristic look when it's under tank sealant.

[MooneyMitch]

Since we're in the fuel tank discussion mode, I will speak up again regarding fuel tank repair and complete strip and reseal.

Advanced Aircraft Setvice, Troutdale, Oregon is an MSC. Greg Lehman is the person to speak with.

I've been through one complete reseal on a 1965 E and 2 repairs on a1994 R.  Perfect results each time.

Based on other business transactions and tank issues with Greg, Advanced, in my experiences, is an honest, efficient and top quality business.

[mooniac15u]

Just now, Hyett6420 said:

@mooniac15u just for you.  And this is what aeroskill do with a condition report.  Literally good enough for uneducated idiots like me.  nice rings to show me where to look    

Thanks!!  That's very visible.  It helps a lot to know what to look for.  I can't quite tell from the photo, is the sealant missing or just bubbled up in those locations?

[aviatoreb]

Ugh - it brings back unhappy memories to see a tank reseal trigger an expensive corrosion fix.  That is exactly what happened to me last year.  I had one spar cap with "slightly" beyond speck corrosion that required a spar cap to be replaced - boy that was a major distraction - and expensive.  But happily behind me.  Luckily it was on one wing on one spar cap and apparently a spot corrosion attack - and I had the rest of the plane re-inspected inside and out before I proceeded with an expensive fix.  Tanks are resealed now too.  Thanks to the guys at weepnomore.

[MooneyMitch]

I should clarify that Advanced is an option for anyone.  Yes, of course Paul Beck.  Advanced may be a closer option for Western US folks. 

[Ron McBride]

1 hour ago, MooneyMitch said:

Since we're in the fuel tank discussion mode, I will speak up again regarding fuel tank repair and complete strip and reseal.

Advanced Aircraft Setvice, Troutdale, Oregon is an MSC. Greg Lehman is the person to speak with.

I've been through one complete reseal on a 1965 E and 2 repairs on a1994 R.  Perfect results each time.

Based on other business transactions and tank issues with Greg, Advanced, in my experiences, is an honest, efficient and top quality business.

Greg did my tanks August of 2015 for me.  They do not leak.  They were done on time, on budget per the quote.   Greg will also help you connect with airline flights.

I had done a couple of patches in my F. My sealant was original 1969.  It was still solid, just weak in a couple of areas.   I have experience in looking for roof leaks and repairing them, the procedures are similar.   I would not try to do a complete strip and reseal on my own, with or without supervision.

Ron

[aviatoreb]

23 minutes ago, Hyett6420 said:

I'll go out on a limb here and say that in my opinion it is the corrosion that cause the leaks as it bubbles the sealant and then the fuel escapes.  I'm not an engineer but it seems logical to me.  I don't think the fuel leaks and then the corrosion starts, that doesn't make logical sense. So if you are having leak issues I would hazard a guess that you also have corrosion.  One of the other aircraft at Aeroskill has this problem. Slight leaks, large corrosion on the spar cap. 

In my case - I did not yet have a leak.  I was planning on getting my airplane painted because the paint was old and tired - and the tanks had never been resealed on a 1981 airplane so I figured I had better get tanks resealed first.  Actually I am glad I did because the big job of replacing a spar cap wrecks the paint. SO I am glad that was done before paint.

[mooniac15u]

1 hour ago, Hyett6420 said:

@mooniac15u just for you.  And this is what aeroskill do with a condition report.  Literally good enough for uneducated idiots like me.  nice rings to show me where to look    

As I look closer at this, and the photos in the refit thread, all of the corrosion appears to originate at metal seams and spread outward.  I wonder if water was getting in through the seams from the other side via capillary action rather than originating in the tank.

[aviatoreb]

15 minutes ago, bluehighwayflyer said:

^ This. Keep your powder dry, boys, and your airplane by keeping her in a hangar and never intentionally introducing water.  In over 10 years I have never washed mine.

And I haven't taken a shower in over 10 years either.

[thinwing]

And even my own dog will approach me!

[Guest]

Would it be cruel to say that my brand P is factory primed and has bladders?

Clarence

[MB65E]

37 years on original tanks. 

16 years on a Wet Wing Logistics full Reseal. 

1 rivet on the left tank is starting to get moist again. 

The Aeroseal product sold by the AeroTrim guys, anyone know what it is? I've heard locktite thinned works well With suction on the tank. 

I wouldn't object to a dime size goober of proseal on the rivet!! Ha!

-Matt

[Mooneymite]

On 2/2/2017 at 11:26 PM, M20Doc said:

Would it be cruel to say that my brand P is factory primed and has bladders?

Clarence

But, if corrosion was attacking a spar under the bladder, would you catch it early enough to fix it before it was major?

[Guest]

2 hours ago, Mooneymite said:

But, if corrosion was attacking a spar under the bladder, would you catch it early enough to fix it before it was major?

Not any sooner than in a Mooney, however Comanches aren't generally known for corrosion issues.

Clarence