Side Windows

[FlyRye]

I have a 62 M20C where the windows doesn't have a good seal and draws some moisture in.

Can I remove, clean and reinstall them or do I have to replace with new? If I can reuse them, what is the recommended seal? Can I use 3M windo-weld, Ribbon Seal?

Has anyone done these without the help of a shop or A&P? Any tips?

Thanks, 

Ryan

[N201MKTurbo]

I've never heard of anybody doing a reseal but I don't see any reason not to if your windows are in good shape. 

Remove the interior panels then mark all the mounting tabs so you can put them back in the same place. Take pictures of the tabs so you can put them back in the same place. Remove all the screws and gently pry the plexiglass and skin apart from inside using an ATS skin wedge. When the window is out carefully clean all the old sealant off of the window with a plastic scraper  and your fingernail. You won't be able to use solvent on the window you can try soap and water for the last little bits. Clean all the sealant off of the skin with a plastic scraper and then MEK for the final cleaning. Don't use dish soap to clean the plexiglass it will leave a film that will keep the sealant from sticking use dishwasher soap it is much stronger and doesn't leave a film behind. 

Apply sealant to both the skin and the window. Using a gloved finger work the sealant into both surfaces. Add another bead if needed and put the window back in and tighten all the hardware before the sealant starts to cure. Use the B2 sealant so you don't have to rush. Let the extruded sealant cure overnight and you can cut the extruded bead free with a plastic scraper and peal it off, if you wipe it off before it cures it will be a lot more difficult to clean up.

As for the sealant I don't remember the exact number but it is a polysolfide sealant like tank sealant.

[TTaylor]

N201MKTurbo's advice is good.   Some factors to consider are the age of the windows and the thickness.  Plexiglass gets brittle as it ages and with exposure to sunlight.  If the windows are old or the plane has been stored outside they are likely brittle now.  In addition the original windows were 0.125 inches in thickness which crack easily when older.

If you have old and/or sunlight exposed 0.125 inch windows with old sealant the chances of getting them out without breaking is very low.   New windows are called green plexiglass because the plexi is still soft and are much easier to bend and work with without cracking.  Replacing windows is a great deal of work, when it is all said and done the cost of new windows, if yours are old, is money well spent.  Plus you could upgrade to solar grey while you are at it.

 

[carusoam]

Going through all the effort and leaving in the old plastic will probably be a learning experience.

1) you will learn that new Windows don't cost very much.

2) acrylic is pretty brittle in it's new state.  Worse with age.

3) special drills and counter-sinks are available to drill holes in acrylic.  Available from the window supplier for a few bucks...

4) it is easy to use the old windows as a template.

5) improper sealing and old insulation has been known to ruin steal tubes in Mooneys.

6) having a good cover is a nice first layer of protection for keeping rain from running in.

Welcome aboard,

-a-

[Htwjr]

I have a '67 C and I replaced all of the side windows a few months ago.  If your windows are old or cloudy I would not want to do all of the work without replacing with new and I also have doubts about not cracking the old ones.  I was able to remove mine in one piece but they did have some cracks around the screw holes.  I used solar grey for the front two and dark tint for the rear and I really like the way it looks,  from inside and out.  Mine had the old green tint which was cloudy and crazed.  You can use the old ones as a rough template for the outside dimensions but not for the holes.  I used a belt sander to get then to fit then held them inside while someone drilled holes from outside the plane.  We then countersunk the holes to fit flush with the skin which has countersunk holes for the screws.  Be sure to buy the drill bits and countersink bit that is made for acrylic.  I did not think it was too bad of a job.  I have not replaced the interior plastic panels yet as I am in the process of repairing and painting them. 

[jrwilson]

On my C, the Windows were good but the sealant was bad and a bit of extra pressure by the wife on entry caused the sealant to let go.  The A & P removed all the side windows, we cleaned the old seal off (time consuming) and resealed them.  

Windows were fine for the next ten years I owned it.

Edited January 7, 2017 by jrwilson

[DonMuncy]

I replaced my side windows, and considering the effort, sealant costs and price of new "glass", I would lean toward new, if you can afford it. I used a sealant from "Flame master" if my memory is working right. If someone doesn't step in with the correct name for it, I could go back and look it up. I would be careful to use the best sealant available. I have heard horror stories about rusted structural tubes from leaking windows.  

[cliffy]

IIRC as I haven't taken the time to look it up, there is a service bulletin to remove the interior and squirt a water hose on the outside of the windows to look for leaks. I think it's an annual repeat. I know I know not for us pt 91 flyers.  But, this is where rusty tubes come from.That's why a good PPI should include removing the interior to check the tubes under the side windows. 

[bradp]

I just did this project myself last summer. I'm really pleased with the result.

Depending on when the windows were last replaced, they will become brittle. I was really careful to try to save my old windows for trimming and "just in case" but I was not able to remove the rear ones despite best effort without cracking them.

The price of the basic side windows is very reasonable (less than a set of spark plugs) if you go with the original thickness and no special tints or coatings. Prices rise steeply if you get fancy materials. Since I was doing all the labor, I went with fancy stuff in my budget. I don't notice that the slightly thicker glass is quieter, but I did do the UV - IR coating which makes a huge difference for heat inside and I think it was worth it.

If you ware able to get the windows out, then I'd recommend reconditioning with micro mesh to take out some of the hazing.

If you are paying someone else to do that much labor (15-20hrs I'd imagine), more for refurbish, just get new windows.

A leaky window would be a do not pass go, inspect ASAP as that is the primary cause of tubular frame corrosion (sb-208).

The sealant is fuel access door panel sealant cs3330-b2. Hard to find retail. Available at Avial or another wholesale distributor. Unfortunately also available through sky geek retail. Don't expect it to show up for 2-4 weeks if you use sky geek. Also check the expiration date.

It's a heated hangar or summer project. Winter temps if you live in winter climate will prevent curing of the sealant. The number of tubes is exactly what the MM calls for.

You can use isopropyl alcohol on acrylic without damaging it. Isopropyl also removes the old sealant.

Don't forget to check the integrity of the wing root seals while you have the interior out. A leaky wing root is in very close proximity to your very valuable wing spar.

PM me if you'd like more details or have questions.


Sent from my iPhone using Tapatalk

[FlyRye]

Thank you all for your response.

The windows themselves seem to be in good shape. I just don't want the leaks to lead to a bigger issue, which I imagine is the inevitable. 

Considering the time it may take to clean, assuming I don't break them during removal, it might be worth buying new ones.

Thanks again for everyone's input!

Ryan

[Guest]

On January 8, 2017 at 1:52 AM, FlyRye said:

Thank you all for your response.

The windows themselves seem to be in good shape. I just don't want the leaks to lead to a bigger issue, which I imagine is the inevitable. 

Considering the time it may take to clean, assuming I don't break them during removal, it might be worth buying new ones.

Thanks again for everyone's input!

Ryan

Ryan,

Here is Mooney SB M20-208b, it calls for inspection of the steel tubular structure, replacement of cabin insulation and re-sealing of the windows.

http://www.mooney.com/en/sb/M20-208B.pdf

Clarence