can you tell if this is corrosion?

[rbridges]

this is the floor behind the back seats and the baggage compartment.  I pushed the rear seats forward to take a look at the area.  Without removing the back seats, I can't really get back there well.  I can scratch the area with my fingernail, and it's pretty rough feeling.  Didn't have time to mess with it tonight.  I have dropped the belly pan in the past and looked around.  I have never seen any corrosion underneath the plane.  Is it some sort of galvanic issue where the seat is attached? Just for reference, the maroon is the seat back, the bottom of the pic is where the baggage compartment begins.  Leave it alone? sand it? burn my plane?  Any recommendations are appreciated.  

[Yetti]

Yes it is corrosion.  Looks like it was there last person to have the seat out.  see where seat rod scratched the top of the black stuff.  No not galvanic from the seat rail, there is some over away from the rail. Could take everything out and clean it up and shoot it with some primer.  Maybe a soda got spilled or some water leaked in.

[rbridges]

3 minutes ago, Yetti said:

Yes it is corrosion.  Looks like it was there last person to have the seat out.  see where seat rod scratched the top of the black stuff.  No not galvanic from the seat rail, there is some over away from the rail. Could take everything out and clean it up and shoot it with some primer.  Maybe a soda got spilled or some water leaked in.

ugh.  Do you think it should be easy to treat?

[takair]

I agree with Yetti, likely some sort of drink spilled and went down the seat.  I don't think that pan is much of a structure, it is more of a enclosure.  Note the non-structural close outs adjacent to it.  It would be important to be sure it did not get into the underlying structure and most importantly the spar.  I would gain access to inspect in detail. Hopefully it is just the sheetmetal and you should be able to clean and prime.  My guess is that you will be fine after a little elbow grease.

[rbridges]

I sent an email to Joey Cole, and he actually answered it on a Sunday night.  That is some good customer service.  He agreed with you guys, but he did mention possible galvanic corrosion; he says he sees it a lot in that same spot.  He also asked for pics of the spar and more pics when the seat and bracket is removed.

Dumb question, can't you see the top of the spar with the rear seat removed?

[Andy95W]

Yes, the main spar is basically the front edge of the back seat. 

I would actually be more concerned about the stub spar (the rear spar) that is the aft attach point of the landing gear legs and corresponds roughly to the forward floor edge of the baggage compartment. You can see the top edge of it with the back seat out.  

[rbridges]

2 minutes ago, N1395W said:

Yes, the main spar is basically the front edge of the back seat. 

I would actually be more concerned about the stub spar (the rear spar) that is the aft attach point of the landing gear legs and corresponds roughly to the forward floor edge of the baggage compartment. You can see the top edge of it with the back seat out.  

great.  My IA said he'd look at it tomorrow.  I'm curious to see what's underneath when the seat is gone.  Right now, we plan to sand and spray with zinc chromate primer if everything looks good.  I'm shooting pics to Joey Cole just to verify.  

[bradp]

When you're done cleaning it up do this ... foil tape generously to protect from future spills. Inspect annually.


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[eman1200]

I sent an email to Joey Cole, and he actually answered it on a Sunday night.  That is some good customer service.

I had a very similar experience with Joey. Emailed him a few basic questions and he called me several times until everything was answered. Hope to use his services one day.

[rbridges]

Just now, eman1200 said:

 

I had a very similar experience with Joey. Emailed him a few basic questions and he called me several times until everything was answered. Hope to use his services one day.

 

After finding this, I think I'm going to have him do my next annual.  I think I need a fresh set of eyes on my plane.

[jetdriven]

Are we talking about the black stuff on the floor? Are we  sure that's not just old glued down carpet residue?

[rbridges]

15 minutes ago, jetdriven said:

Are we talking about the black stuff on the floor? Are we  sure that's not just old glued down carpet residue?

it's underneath the seats.  Would there have been adhesive there originally?  I guess we could verify that with some type of acetone.

[jwilcoxon78]

15 hours ago, rbridges said:

I sent an email to Joey Cole, and he actually answered it on a Sunday night.  That is some good customer service.  He agreed with you guys, but he did mention possible galvanic corrosion; he says he sees it a lot in that same spot.  He also asked for pics of the spar and more pics when the seat and bracket is removed.

Dumb question, can't you see the top of the spar with the rear seat removed?

Joey addressed somewhat the same issue on mine during the prebuy.  Pretty non-invasive to clean up and treat.  I don't see it as being a big deal.

[thinwing]

4 hours ago, jetdriven said:

Are we talking about the black stuff on the floor? Are we  sure that's not just old glued down carpet residue?

That's exactly what I was thinking...aluminum corrosion is white powdered...

[rbridges]

10 minutes ago, thinwing said:

That's exactly what I was thinking...aluminum corrosion is white powdered...

that would be nice.  keeping my fingers crossed.

[Marauder]

that would be nice.  keeping my fingers crossed.

There was a lot of duct tape used on mine that left both a off white and black residue. The black stuff was goo that had picked up dirt.

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[rbridges]

it was pretty crusty feeling to my fingernail, but I really couldn't get to it well.  I may try a toothbrush with some acetone to see if it removes a spot of it.

[thinwing]

Or Mek/lacquer thinner before you start scraping/sanding

[rbridges]

took the rear seat bottoms out.  I'm not really sure what to make of it.  Mineral Spirits lightened it but didn't remove it.  I think some areas may be old hardened adhesive, but I think the seat belt attachment may be actual oxidation.  What would you recommend to sand the aluminum in that area?  

[rbridges]

 

I did notice some corrosion on the rear seat mount.  Weird. Why would that area show rust when I'm not really seeing it anywhere else?

[XXX]

4 minutes ago, rbridges said:

 

I did notice some corrosion on the rear seat mount.  Weird. Why would that area show rust when I'm not really seeing it anywhere else?

It is funny that you posted this. Just this weekend while vacuuming my cargo area, I noticed my rear seat bottom was not attached on the left side. I decided to take it out and have a look and found a very similar looking residue. It is sticky and probably an old soda spill from the previous owner.  Lots of duct tape too like Marauder found on his. I didn't see any indication of corrosion.

One thing I did notice that seemed odd was how the restraints were attached. The inner restraints are attached with one bolt and a 3/4 sleeve in between. The outer restraints look like yours, but there are no washers or spacers, just the bolt and castle nut with the belt free to slide about an inch (picture the above picture without the washers). This doesn't look correct to me. I feel like there should be a spacer on each of the outboard restraint attach points similar to the inner attach point. Does a anyone remember seeing a spacer here or are the washers how Mooney did it?

 

 

[Cyril Gibb]

On mine, the belt metal component rides on a short metal sleeve between two washers to allow it freedom without touching the shank of the bolt directly.  Also, it appears that the excessive number of washers on the too long bolt is causing the bolt shank to bend, even with casual use..  Not good in the case of a sudden load. (crash)

[rbridges]

Just now, Cyril Gibb said:

On mine, the belt metal component rides on a short metal sleeve between two washers to allow it freedom without touching the shank of the bolt directly.  Also, it appears that the excessive number of washers on the too long bolt is causing the bolt shank to bend, even with casual use..  Not good in the case of a sudden load. (crash)

I think that's an illusion from the reflection.  I have a C model. No one uses the back seats.  

[XXX]

4 minutes ago, Cyril Gibb said:

On mine, the belt metal component rides on a short metal sleeve between two washers to allow it freedom without touching the shank of the bolt directly.  Also, it appears that the excessive number of washers on the too long bolt is causing the bolt shank to bend, even with casual use..  Not good in the case of a sudden load. (crash)

Wow, that's what is so awesome about Mooneyspace. Ask a question and not even ten minutes later you get an answer. Thanks Cyril! 

So yes, there should be a sleeve on each outer attach point. Just as I thought. I didn't like the idea of the clasp riding on the shank which is how it is set up now. 

[Marauder]

took the rear seat bottoms out.  I'm not really sure what to make of it.  Mineral Spirits lightened it but didn't remove it.  I think some areas may be old hardened adhesive, but I think the seat belt attachment may be actual oxidation.  What would you recommend to sand the aluminum in that area?  

Each of those panels had duct tape on them. What I am seeing is the duct tape has been removed and what you are left with is the glue residue that collected dust.

Maybe one of the mechanics can chime in but I believe those panels are supposed to be sealed. I sealed mine by removing the cloth duct tape and replacing them with metal waterproof duct tape.

Take a look at this picture Bruce Jaeger sent me. You can see the cloth duct tape on the seam across the front and around one of the panels on the left. All of mine looked like that and the cloth duct tape had deteriorated. I opened each of the panels, looked inside, saw no corrosion and gave them a shot of Boeshield and then sealed them.




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