Look what we found under the window….Corrosion

[c1tice]

Look what we found while installing a new GFC500 in my 1981 M20K. My mechanic says we caught it in time and needs a good sanding and treatment. This Mooney sat on the ramp in FL for a few years before I bought it 2 years ago. Might I suggest a look behind the panels and under the windows during the next PPI to check for leaks and corrosion, which I did not do but will next time. This is why our birds need to be in a hanger, in my opinion. Also going to replace that water holding insulation. I would like to see your corrosion photos too so we know what to look for. 

[N201MKTurbo]

There is a service bulletin about that. I’m surprised it wasn’t checked years ago.

[chriscalandro]

A cover would have prevented that. 

[Mooneymite]

1 hour ago, N201MKTurbo said:

There is a service bulletin about that. I’m surprised it wasn’t checked years ago.

 

Excellent reason the inspection portion of SB 208B should be completed periodically and certainly as part of every PPI.

You never know until you look.

[PT20J]

Given that amount of surface corrosion, I would really want to pull the tension bolts and do the full inspection called out in the SB were it mine. And, of course the insulation needs to be replaced with the newer foam insulation. 

After cleaning up the corrosion, It would be best to repaint the tubes with epoxy primer like the factory started doing on later models. It's much better protection than the zinc chromate.

Skip

 

[StevenL757]

22 minutes ago, PT20J said:

Given that amount of surface corrosion, I would really want to pull the tension bolts and do the full inspection called out in the SB were it mine. And, of course the insulation needs to be replaced with the newer foam insulation. 

After cleaning up the corrosion, It would be best to repaint the tubes with epoxy primer like the factory started doing on later models. It's much better protection than the zinc chromate.

Absolutely agree.  I can’t imagine that much corrosion would be confined only to the areas shown, but sincerely hope it’s able to be fully-remediated.

[A64Pilot]

When I bought mine I only checked under the pilot side window as I’ve read it’s the worst spot, I didn’t find corrosion. That SB was never complied with on mine as I believe it has the fiberglass insulation.

A cover certainly will help but often the temp changes in a humid climate will cause condensation inside a covered airplane, the condensation occurs inside of the skin, I’m sure we have all seen wet floors even inside of a hangar when the weather suddenly warms up and the cold floor causes condensation.

I think if you live in a humid area to really deal with it you need to dehumidify the hangar, without a dehumidifier humidity in my hangar at times was 80% maybe higher, a dehumidifier keeps it in the 50’s%.

However I did have one corroded tube about 3” or so under the panel that made no sense to me, then figured out it was inline with the vent and based on the leading edge paint on my airplane it spent some time in rain, then the isolated corrosion made sense, the vent was blowing water on it, or that’s my theory anyway.

I believe we are only allowed 10% depth of the thickness of the tube for corrosion, which isn’t much at all, 2.5 thou for a .025 tube for instance, so be very careful on clean-up.

Coming from Crop dusters that are always wet and the entire fuselage is tubing, I’ve had very good luck with rust convertor primer which takes the iron oxide and chemically converts it and does stop rust from coming back, prior to using it, it seemed often the rust would re-occur especially in clusters. Rust it seems you have to get every bit or it comes back and it’s not always possible to get every bit.

And by all means top coat with epoxy, zinc chromate had its day, but epoxy is much better, much tougher to remove too though.

[Guest]

6 hours ago, c1tice said:

Look what we found while installing a new GFC500 in my 1981 M20K. My mechanic says we caught it in time and needs a good sanding and treatment. This Mooney sat on the ramp in FL for a few years before I bought it 2 years ago. Might I suggest a look behind the panels and under the windows during the next PPI to check for leaks and corrosion, which I did not do but will next time. This is why our birds need to be in a hanger, in my opinion. Also going to replace that water holding insulation. I would like to see your corrosion photos too so we know what to look for. 

There looks to be a deep pit in the tube by the oxygen outlet.

[Guest]

Mooney is kind enough to provide corrosion limits in the SB

[RoundTwo]

I need to bookmark this thread and refer certain sellers who tell me a PPI is a waste of my money because their plane doesn’t have any corrosion. 

[A64Pilot]

18 hours ago, bluehighwayflyer said:

All airplanes have corrosion.  It is just a question of degree.  

And Corrosion is often the death knell. I believe there is a K model at the local Junkyard that’s there from Corrosion that’s newer than my J model. Flying colors airparts.

People who tie down in Fl have to know the deal, especially near the coast. I had one guy get upset with me telling me that hangar rates are so expensive in S Fl that it cheaper to tie down and just scrap the airplane in a few years, then buy another.

But I suspect they usually sell them

[1980Mooney]

That looks pretty serious and there are probably other deep areas upon close examination. But the good news is it is repairable. Unfortunately the skin of the fuselage aluminum skin will need to be removed in order to cut and weld full circumference (or weld doublers if allowed). This YouTube shows it opened up.   At least with the aluminum skin there is the possibility of repair with the composite shell of the Ultra I doubt it would be repairable. 

 

[tony]

On 1/28/2023 at 8:54 AM, c1tice said:

Look what we found while installing a new GFC500 in my 1981 M20K. My mechanic says we caught it in time and needs a good sanding and treatment. This Mooney sat on the ramp in FL for a few years before I bought it 2 years ago. Might I suggest a look behind the panels and under the windows during the next PPI to check for leaks and corrosion, which I did not do but will next time. This is why our birds need to be in a hanger, in my opinion. Also going to replace that water holding insulation. I would like to see your corrosion photos too so we know what to look for. 

I wish you wouldn't post things like this.. The factory will see it and turn it into a Service Bulletin, then the FAA will freak out and turn in into a fix before flight AD......

 

but you found it during an annual didnt ya?

[1980Mooney]

3 minutes ago, tony said:

I wish you wouldn't post things like this.. The factory will see it and turn it into a Service Bulletin, then the FAA will freak out and turn in into a fix before flight AD......

 

but you found it during an annual didnt ya?

The first line of his post says "Look what we found while installing a new GFC500". You don't usually pull side panels during an Annual.  But the Avionics shop will pull the pilot side panel to run new wiring.

And SB M20-208B was issued in 1989 - it is a well known problem that every Mooney should be inspected for and logged and should be checked during a Per Purchase Inspection.

SBM20-208B.pdf (mooney.com)

[chriscalandro]

On 1/29/2023 at 1:26 PM, A64Pilot said:

And Corrosion is often the death knell. I believe there is a K model at the local Junkyard that’s there from Corrosion that’s newer than my J model. Flying colors airparts.

People who tie down in Fl have to know the deal, especially near the coast. I had one guy get upset with me telling me that hangar rates are so expensive in S Fl that it cheaper to tie down and just scrap the airplane in a few years, then buy another.

But I suspect they usually sell them

If you’re airplane is tied down in Florida and it’s properly cleaned and maintained it’s not a problem. 

[tony]

4 minutes ago, 1980Mooney said:

The first line of his post says "Look what we found while installing a new GFC500". You don't usually pull side panels during an Annual.  But the Avionics shop will pull the pilot side panel to run new wiring.

And SB M20-208B was issued in 1989 - it is a well known problem that every Mooney should be inspected for and logged and should be checked during a Per Purchase Inspection.

SBM20-208B.pdf (mooney.com)

this was a joke to make fun of AD 2023-02-04

[chriscalandro]

18 minutes ago, tony said:

I wish you wouldn't post things like this.. The factory will see it and turn it into a Service Bulletin, then the FAA will freak out and turn in into a fix before flight AD......

 

but you found it during an annual didnt ya?

Then if you try to fix it yourself they will tell you the replacement tubing you used isn’t authorized and only tubing sourced from them is acceptable. 

[ArtVandelay]

In addition to corrosion protection, another preventive measure is to make sure your windows are properly sealed.

[1980Mooney]

1 hour ago, tony said:

this was a joke to make fun of AD 2023-02-04

I didn’t have my coffee this morning…

I can only imagine that the OP is sick right now….all excited to launch into an expensive avionics upgrade which has probably been derailed in the middle of the job. All the wiring needs to be detached from the tubulars. Sanding, painting, perhaps stripping exterior aluminum and welding. Additional cost - and replace all the glass fiber insulation. And how was this missed in the pre buy? - either by examining the logs and/or pulling panels. 

[A64Pilot]

On 2/2/2023 at 11:21 AM, chriscalandro said:

If you’re airplane is tied down in Florida and it’s properly cleaned and maintained it’s not a problem. 

Yeah, maybe if you maintain it like the US Navy, maybe. But their aircraft are manufactured knowing that they will live in a Corrosive environment, Corrosion is why the Naval Apache never made it, it wasn’t manufacturers with the idea of being put in a corrosive environment.

Neither was a Mooney.

But That’s not what I see with most aircraft tied down, you can never say 100% with anything, but you can determine averages.

I would be very, very careful buying an airplane that was tied out much, especially in Florida, and yes you go down to South Fl and you see it, even with newer high buck airplanes.

‘I live in Fl and can say if you are buying an aircraft in Fl, first check where it’s been stored, save yourself some grief, and if everything looks good, really dig into it, which is invasive and some may not allow it, so walk.

[jkgyr52]

Twelve years ago I bought a 78 J model that had lived in a hangar for > 20 yrs @ Lake Havasu City (HII), in a hot dry desert environment. Light surface corrosion was on all tubes (including aft of the firewall) and the one below the window (aft) @ the right side passenger seat had to be cut out and a new tube was welded by a FAA certified welder. The log books never indicated it living in the corrosion zone. I surmised that when the monsoon rains in Arizona occurred, it was very hot and the metal building "sweated", thus making the hangar very humid. Perhaps it sat outside in the rain prior to living in Arizona.

I have owned a E, G, J, and 4 K models over ~ 40 yrs and on every one I removed the entire interior (for refurbishing) and performed the 208BSB. Six of the airplanes had the old style insulation with evidence of moisture,. The E model was junked because too many tubes were ruined. In the early years no IA suggested removing interior as part of the PPI.

Jeff

 

[carusoam]

Note…

1) Corrosion is a problem for all metal planes… 

2) Oddly, The video about Mooney corrosion was put together by a guy who sells planes for a living…

3) Surface corrosion is the easy to see part…

4) When corrosion progresses… it can pick up speed, and dig deeply into the tube structure…

5) Replacing tubes are pretty straight forwards…

6) Replacing aluminum spars gets more complex…

7) Remember… there are two surfaces to a tube… the inner surface is much harder to see…

8) The sad remainders of the original insulation are kind of a weird reminder of what wasn’T finished properly…

9) There were three things that were known causes of this challenge…. 
 

• Leaking window seals allowing rain water to enter the cabin…
• The original insulation was good at keeping any water that entered the plane from drying out…
• paint scratches and wear exposing the surface…
• some of the tubes are open ended to allow water to drain out…

When you find corrosion… get on it.

Much easier to stop it early, than to find it accelerating at the next annual…. It doesn’t get better with time…

10) There are methods to ascertain the tube’s health… measuring the depth of any damage is easy for the visible side…

When you see an abandoned plane, uncared for… it is really extra important to be on the look out for corrosion and it’s sources… it only takes a couple of years of exposure to the elements to see tubes rotted all the way through…

Window seals are at a high risk of leaking… they get really hot in the summer, and have a tendency to break down over decades…

If your plane has to live outside… get it a cover.

PP thoughts only, not a mechanic… 

Best regards,

-a-

[jlunseth]

13 hours ago, jkgyr52 said:

 

I have owned a E, G, J, and 4 K models over ~ 40 yrs and on every one I removed the entire interior (for refurbishing) and performed the 208BSB. Six of the airplanes had the old style insulation with evidence of moisture,. The E model was junked because too many tubes were ruined. In the early years no IA suggested removing interior as part of the PPI.

Jeff

 

Same here. No panels removed when I bought mine and we found corrosion on some of the tubes caused by the insulation. It was a wool or wool-type insulation that would hold moisture and the edges were up against the tubes. Wish I had known. The repairs were done by Willmar Aviation when Bruce Jaeger owned it and have not been a problem since.

[M20F]

Covers and hangers don’t stop corrosion, corrosion-x stops corrosion. 

[DCarlton]

10 hours ago, carusoam said:

Note…

1) Corrosion is a problem for all metal planes… 

2) Oddly, The video about Mooney corrosion was put together by a guy who sells planes for a living…

3) Surface corrosion is the easy to see part…

4) When corrosion progresses… it can pick up speed, and dig deeply into the tube structure…

5) Replacing tubes are pretty straight forwards…

6) Replacing aluminum spars gets more complex…

7) Remember… there are two surfaces to a tube… the inner surface is much harder to see…

8) The sad remainders of the original insulation are kind of a weird reminder of what wasn’T finished properly…

9) There were three things that were known causes of this challenge…. 
 

• Leaking window seals allowing rain water to enter the cabin…
• The original insulation was good at keeping any water that entered the plane from drying out…
• paint scratches and wear exposing the surface…
• some of the tubes are open ended to allow water to drain out…

When you find corrosion… get on it.

Much easier to stop it early, than to find it accelerating at the next annual…. It doesn’t get better with time…

10) There are methods to ascertain the tube’s health… measuring the depth of any damage is easy for the visible side…

When you see an abandoned plane, uncared for… it is really extra important to be on the look out for corrosion and it’s sources… it only takes a couple of years of exposure to the elements to see tubes rotted all the way through…

Window seals are at a high risk of leaking… they get really hot in the summer, and have a tendency to break down over decades…

If your plane has to live outside… get it a cover.

PP thoughts only, not a mechanic… 

Best regards,

-a-

Skywagons seems to move a lot of M20s; he's had some nice ones.  I would like to have seen a close up of the tubes that were cut out in that airplane.  

Posts like this convince me over and over again to keep flying the same Mooney I've been flying for 20 years.  Always wondered how hard it would be to convince a seller to let you do a really thorough PPI, to include removing the interior, particularly when the market is hot.