Lower Spar Corrosion - in fuel tank

[aviatoreb]

2 minutes ago, carusoam said:

Erik,

Thanks for taking the time to cover so many details.

Best regards,

-a-

:-)  You get out to 39N and check out my new interior?

Paint is postponed until April 24 to fit that shop's schedule.  Which is fine with me - I don't mind flying a scruffy airplane for a few months.

[DXB]

@aviatoreb wow that's quite the painful saga - glad you're almost on the other side of it!  I think I saw your bird opened up while it was down at Airmods. They certainly seem to have a special expertise when it comes to heavy duty air frame work.  Going forward I think I'm gonna keep rotating mine through them or Weber every couple of years.  I've finally found a non-MSC mechanic who I will trust for reasonably priced, routine work on the non-Mooney specific stuff now after two pricey annuals at top MSCs.  But he can't replace them entirely.

[aviatoreb]

Just now, DXB said:

@aviatoreb wow that's quite the painful saga - glad you're almost on the other side of it!  I think I saw your bird opened up while it was down at Airmods. They certainly seem to have a special expertise when it comes to heavy duty air frame work.  Going forward I think I'm gonna keep rotating mine through them or Weber every couple of years.  I've finally found a non-MSC mechanic who I will trust for reasonably priced, routine work on the non-Mooney specific stuff now after two pricey annuals at top MSCs.  But he can't replace them entirely.

It was painful!  Doh....  For now on - I too will be doing a weber/airmods rotation for my annuals.

Having flown down here yesterday, popping up through clouds, running my tks (just in case), sitting on my lovely new leather interior, I was feeling quite fine.  On flight aware.

Only the repaint is waiting now - due to start on April 24.

[cnoe]

Many of us feel sick for Paul's situation. He just sold his beloved C stepping up to a nice 252. After some significant avionics upgrades the tank issue pops up, which now turns into a possible airframe issue. From the one picture it doesn't look that bad but we're not the experts and I know Paul will fix it properly.

My question is this... once your tanks are stripped and resealed by a top shop that specializes in such work is it reasonable to assume that such a problem can be dismissed on your plane (as long as you keep the tanks free of water)?

This might be a valid reason for a premium on planes that have had this work completed in the recent past.


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[Sabremech]

This is the exact reason I will be stripping the sealant off of the spar in both tanks before committing to painting my airplane. 

David

[aviatoreb]

1 hour ago, Sabremech said:

This is the exact reason I will be stripping the sealant off of the spar in both tanks before committing to painting my airplane. 

David

Apparently that was my plan before painting - only I didn't realize it ahead of time that it was my plan!

[gsxrpilot]

I started another thread asking for a ride to LASAR to look at a wing.  I'll update this thread to keep the story all in one place.

I flew the plane back from ELA to my home base at HYI. And we're looking at options for a repair. Brian Kendrick is now helping me to find a DER who can prescribe the requirements for a repair.  I still believe that a relatively small spar cap splice will be all that is required. If a DER will agree, that's what we'll do and then finish sealing up the tank. I have not stripped the Left tank and therefore don't know if there is any like corrosion on that side. But by all indications, the one small spot of corrosion in the right wing wouldn't seem to indicate anything about the left wing.  If there were several spots, then I'd be more likely to assume that the spots might continue to the other wing. At this point, I have no plans to strip the left tank.

I am talking with LASAR about the 252 wing they have for sale. Of course if I get a DER approved repair, I won't need the wing. But if the DER requires an entirely new spar cap, then the wing is probably a better option.  The $50K question is of course, do you strip the tanks in the salvage wing, and what are the chances that corrosion is found there? It would be a shame to buy the wing, ship it across the country, only to have the same problem. Maybe if I committed to buy the wing, put the funds in escrow, pending a strip of both tanks, full inspection, and reseal. And if clean, I take the wing? Just a few things that have to be worked out.

I will say, I'm glad to have her back in my hangar where there are many more options and resources. 

[Yetti]

What did Mooney say?   I would be doing what Piloto said to do.   Have we measured the depth of the pitting?

[gsxrpilot]

1 hour ago, Yetti said:

What did Mooney say?   I would be doing what Piloto said to do.   Have we measured the depth of the pitting?

Mooney hasn't responded yet. And no, the depth hasn't been measured yet. 

[Zwaustin]

6 minutes ago, gsxrpilot said:

Mooney hasn't responded yet. And no, the depth hasn't been measured yet. 

PM me your email.... I'll send you some corrosion pics that I found when scoping a friends plane at annual with my endoscope a few weeks ago. They will make you feel better about what you have assuming you confirmed there is nothing deeper in the wings and the spot posted above was all there was. His started with a tiny spot which is what lead us to dig further and we found quite the motherload where a mirror can not get to. Once you see the pics you'll know what I mean. In helping him out on this issue it seemed that Airframe Components does a lot of wing and spar repairs so they may be worth a call, From reading on MS Airmods does them too. 

[PTK]

I'm curious how corrosion happens inside the fuel tank. Is it good old dihydrogen monoxide sitting at the bottom of the tank? Regular fuel sumping should avoid this I hope?! I sump tanks regularly and have never seen any water. Safe to assume no corrosion?!

[gsxrpilot]

Just now, PTK said:

I'm curious how corrosion happens inside the fuel tank. Is it good old dihydrogen monoxide sitting at the bottom of the tank? Regular fuel sumping should avoid this I hope?!

Good question.  This spot happens to be in the top most section of the right tank. In other words, the furthest out board section. If the tanks are not kept full, that section might have seen periods of dry.  But then the corrosion was completely covered by the original tank sealant. So based on that, fuel or no fuel shouldn't make a difference. And there's no way for water to sit in that location.

[PTK]

14 minutes ago, gsxrpilot said:

Good question.  This spot happens to be in the top most section of the right tank. In other words, the furthest out board section. If the tanks are not kept full, that section might have seen periods of dry.  But then the corrosion was completely covered by the original tank sealant. So based on that, fuel or no fuel shouldn't make a difference. And there's no way for water to sit in that location.

Interesting. Could it be it started in tanks left less than full in the past and then was covered by sealant? Or maybe water was trapped under old sealant?

[gsxrpilot]

8 minutes ago, PTK said:

Could it be it started by tanks left less than full in the past and it started and then was covered by sealant in the past? Or maybe water was trapped under old sealant?

Very well could have.

[Yetti]

Curious if the plane has been repainted.  Stripping agent that worked itself down from the outside?

[aviatoreb]

3 hours ago, gsxrpilot said:

I started another thread asking for a ride to LASAR to look at a wing.  I'll update this thread to keep the story all in one place.

I flew the plane back from ELA to my home base at HYI. And we're looking at options for a repair. Brian Kendrick is now helping me to find a DER who can prescribe the requirements for a repair.  I still believe that a relatively small spar cap splice will be all that is required. If a DER will agree, that's what we'll do and then finish sealing up the tank. I have not stripped the Left tank and therefore don't know if there is any like corrosion on that side. But by all indications, the one small spot of corrosion in the right wing wouldn't seem to indicate anything about the left wing.  If there were several spots, then I'd be more likely to assume that the spots might continue to the other wing. At this point, I have no plans to strip the left tank.

I am talking with LASAR about the 252 wing they have for sale. Of course if I get a DER approved repair, I won't need the wing. But if the DER requires an entirely new spar cap, then the wing is probably a better option.  The $50K question is of course, do you strip the tanks in the salvage wing, and what are the chances that corrosion is found there? It would be a shame to buy the wing, ship it across the country, only to have the same problem. Maybe if I committed to buy the wing, put the funds in escrow, pending a strip of both tanks, full inspection, and reseal. And if clean, I take the wing? Just a few things that have to be worked out.

I will say, I'm glad to have her back in my hangar where there are many more options and resources. 

I can't remember for sure, but I thought that wing was stripped?  I was looking at it about a year ago.

[mike_elliott]

Just now, Hyett6420 said:

it was negligence

Now that's how you get the attention of a lawyer

 

[carusoam]

Ideas related to corrosion...

Keep in mind oxidation does not require water.  

Oxidation is often aided or initiated by the presence of water.

Once it begins, oxidation has a tendency to spread pretty quickly.

Keeping oxygen away from the metal would be better than keeping water away.  Proper coatings are usually what works.

Some metals oxidize nicer than others.  When the volume of the oxide is much larger than the volume of the initial metal, the oxide tends to sluff off, exposing fresh surfaces to oxidize.

Sealants are intended to keep fuel from evaporating or passing through.  Their ability to keep oxygen from passing through or moisture is not readily known.

this all happens at the molecular level.  

- Keep the O2 molecules from getting alignined with the Al molecules would help.

- Keep the O2 molecules from getting near the Al molecules would be better.

- Keep the criminal partner of oxidation away. Water in all forms is not helpful to Mooney ownership.

- Properly clean up any oxidation that starts. Oxidation rates increase as it spreads.

-know that there are two types of oxidation one that spreads on the surface and one that dives into the structure of the metal itself.  It is the type of metal and the process that made the parts that define the type of oxidation that is going to happen.  Spar parts are often victimized by this intragranular type of corrosion.  

- Molecules combine into grains. Grains combine into parts.  This is where the 'intragranular' descriptor comes from.

Finding the corrosion should bring a smile (sort of). It is the beginning of getting the problem fixed.  Catching it sooner, is better than catching it later. Definitely, don't wait a year for the next Annual to happen to decide a course of action.

The source of this post comes from ancient memories of materials engineering classes.

Hoping this can spread some light on how oxidation occurs, spreads, and increases over time.

Keep dry, Keep coated, and if oxidation starts, get it stopped...

Best regards,

-a-

 

 

[Cyril Gibb]

5 hours ago, carusoam said:

Keep in mind oxidation does not require water.  

I'm not sure if I understand the terminology correctly.  If we're talking about corrosion, I thought that all forms of corrosion, including intergranular, required an electrolyte to begin. For us, that would primarily be water.  If we keep water away through either a perfect coating (unlikely) or a water displacement treatment (CorrosionX or equivalent), wouldn't that eliminate the potential for corrosion?

[Bravoman]

Corrosion very much like socialism. Starts small and insidious and must be eradicated:)

[aviatoreb]

8 minutes ago, Bravoman said:

Corrosion very much like socialism. Starts small and insidious and must be eradicated:)

We need a not like button on this forum.

seriously weren't we just talking about corrosion?  If it was just a joke or your brand of politics I wasn't in the mood.

Edited February 12, 2017 by aviatoreb

[Piloto]

11 hours ago, gsxrpilot said:

Mooney hasn't responded yet. And no, the depth hasn't been measured yet. 

It does not take that long to look at the picture, and then there is the liability issue. It will help on an assessment to clean the area well and take another picture. Unlike on a rubber band balsa plane on a Mooney changing the wing is not trivial. There is a lot of gear and flight controls linkage and wiring to deal with. Not to mention handling a one piece wing without getting it ding. 

José

[Andy95W]

1 hour ago, Bravoman said:

Corrosion very much like socialism. Starts small and insidious and must be eradicated:)

 

1 hour ago, aviatoreb said:

We need a not like button on this forum.

seriously weren't we just talking about corrosion?  If it was just a joke or your brand of politics I wasn't in the mood.

Please move your political discussions to the "Rants and Raves" section of the website.  Thank you.

[rpcc]

Andy95w and aviatoreb - read his comment again, you can see his it was said with humor.  Perhaps you two need a special politically correct forum so you are not offended.  

[carusoam]

Welcome on your first post, RPCC.

I think you are making a comment to some people that have some corrosion challenges.  Expensive challenges that are not readily open to not so helpful comments.

in some cases the humor doesn't get understood by everybody.  It is helpful in this case to drop a sign...

Fortunately 99% of MS is still a politically correct venue.  We lose too many good people when they get offended.

i'm sure somewhere in the Mooney World Socialism is a good thing.  The Mooney world covers a lot of distance... Why get tangled up in this...?

Best regards,

-a-

Edited February 13, 2017 by carusoam