M20c rear window replacement

[M20Bdriver]

Anyone ever replace a left or right rear window on a early Mooney M20A, B or C?

[cctsurf]

I'd be curious on this too, 'cause mine are getting fairly hazy.  Also, where is the best place to get the replacement windows?

[M20Bdriver]

Vantage Plane Plastics has early Mooney replacement windows in clear, green or gray tint.

[carusoam]

Get the vantage.

They sell the drill. 

Use the old window as a guide... some trimming may be required...

Lots of old sealant to be cleaned.

Use the new sealant, not silicone.

Select proper window color, the old was actually green in color.  New is a solar gray.  Clear, only if flying in the dark is normal... way to hot inside even in NJ...

Study up on plastic interior bits, cleaning, painting, covering... you have to remove and replace.  Not every part survives the exercise...

 

65C experience...

Best regards,

-a-

[RLCarter]

Never replaced one but like all things Mooney, just a bunch of screws. I would definitely get a plexiglass drill bit for that many holes and use the correct sealant as mentioned above

[Wildhorsesracing]

I replaced mine last year during it's annual because they were pretty hazy.  No drilling needed for the side windows, just the windshield.   My A&P used Bostik 1100 FS for a sealant, it was easy to apply and easy to clean up afterwards.  You will need to trim the windows to fit but it's easy to do with a file, leave some room around the edges for expansion.   I got mine from LP Aero, great quality and I opted for the clear ones.

[takair]

I replaced all my windows a few years ago.  Mine were Great Lakes Aero.  They were not bad, but required some trimming.  Have the right drill bits and the right saw.  If trimming is required a bandsaw with fine teeth is good to have.  I did make one mistake.  I went with clear and even here in New England I notice a big difference in solar heating.  If I did it again I would go with grey.  I had green before, but did not like how it washed out some colors.  I have ended up tinting the rear windows, but have not found a satisfactory tint for the pilot windows (I used the Gila static tint discussed in other threads). Anyway, don’t underestimate the power of the subtle factory tint.

[RobF15E]

I just replaced all of mine with the thicker IR solar grey from LP Aero.  I had an STC one piece sloped windshield from SWTA from 20 years ago.  It took a couple of months for LP Aero to get the approval to make the windshield form me.  The folks there were really helpful as I had some small issues with the glass not having the perfect curve.  I didn't have to do much trimming to the side windows, but a ton to the windshield.  I used my router table and a carbide trimming bit in a rip fence.  It cuts very cleanly.  Now my router table is integrated with a full size Jet table saw, so it isn't going to move or bounce around.  I also used a belt sander for fine tuning the edges.  With a 36 grit belt, it will remove material pretty quickly.  Measure twice, cut a little, measure twice more, cut a little less.....  Don't leave any sharp edges, bevel everything including the screw holes.  Cracks start easily from sharp edges.  I used a countersink to bevel both sides of the screw holes - just a little on the back side, more on the front where the dimpled sheet metal is.  Also drill the holes slightly oversize to allow for less than perfect measuring and thermal expansion of the screws.  Last tip, if you have stubborn caulk/sealant to remove, don't use a wire or nylon bristle bush in a drill.  It will remove the caulk well, but it will also remove the dimpled sheet metal, leaving you a hole that is now too large with no dimple...  Don't ask how I know.....  Don't be afraid of the solar grey tint - it isn't really tint the way we think of it.  What I got from LP Aero looks like 97% light transmissivity.  I have not flown the plane yet, still putting it back together from a lot of work this annual, so I can't comment on the thicker glass or the IR reduction.  Having someone help hold the glass in place while you are drilling is a big help.  I didn't want to end up damaging my sheet metal holes (any more than I already did), so I made a couple of drill guides that worked really well.  I bought some aluminum stand offs on Amazon that had the right sized hole in the center for my pilot bit (1/8) I then ground down the end to make it look like the taper on a flat head screw.  I then was able to lock it into a needle nose vice grip and put it in the countersunk hole and drill through the plexi.  This ensured the pilot hole was centered.  I followed that up with the final sixed drill bit with the plexi on my garage.  Then countersunk and beveled.  I also made a countersink doing the same thing, except I went a step further and epoxied the ground end of the stand off to a #6 beveled washer,  That helped keep the guide perpendicular to the glass.

Separate tip.  Get some zip lock baggies, 1 for each window.  Get a permeant marker.  Put a number on each aluminum tab and on the airframe so you can keep them in the right order.  Make certain that the number you put on the sheet metal is far enough away from the caulk that when you use the nylon brush I told you not to use, you don't clean the number right off the aluminum....  I hate learning the hard way....  You have to put the tabs back in the original spots because of the little holes in you trim.  they are all different.  No automated machines built these planes.  All done by hand.

I also thought I would be cool and rabbit the edges of the thicker windows so they would be flush fitting like some of the really sweet homebuilts I have seen.  Don't.  Not only is it time consuming and difficult on curved plexi, my sheet metal had beveled edges which kept my rabbited edges from being flush fitting anyway..

Anyway, I am not an expert on window installation, just sharing the mistakes I made and the few things that went well.  Follow at you own risk.  I'll see if I can find my homemade drill guides and take a picture.  Oh yeah, plexiglass drill bits only.  Regular drill bits will bit a pull through to fast.  no, I didn't make that mistake.... this time..  ;-)

[MARZ]

One addition to the above - Don't lay your old window on the new to use the holes in the old as a pattern.  It won't work. 

Not impossible to do alone but a helper makes it so much easier........

Put the new window in the plane - mark a hole, drill it, install it back in the plane with one screw as an anchor - mark the next and drill - lather rinse repeat until you get the window secure enough to mark all the remaining holes.  

 

PS - if your wondering if the thicker windows are worth it - yes, yes they are.

PPS - go with the gray - you won't be disappointed. 

[RobF15E]

I am adding pictures of the 2 drill guides I made.  on Amazon I ordered Round Spacer, Aluminum, Plain Finish, #4 Screw Size, 3/16" OD, 0.115" ID, 11/16" Length, Made in US (Pack of 25) They sell less than 25 but I had other uses for them.  The long one has one end ground down for #6 screw and the other for #8.  The shorter one is a #6 countersunk washer epoxied to the spacer.  I had to drill out the hole in the washer since I was using it in the #8 holes.  Drill the hole before you glue it.  I agree with drill one hole put a screw in.  The biggest area I had some trouble with was along the top, because the skin was not fitting close to the glass so it left a couple of holes higher than they should have been.  I drilled the pilot holes with the glass in place, then removed it and drilled the holes to size and countersunk the holes in the garage.

[Sean S]

The thicker windows may be worth it, but they add labor time as all of the retaining clips need to be modified to accommodate the new dimension. I did the door window on my 75F with thicker gray tint. Like the tint, would not do thicker again due to the added labor hours. I was able to back drill from the old window to the new with no problem to pick up all the holes. Still needed to trim more from the perimeter of the window as they are intentionally made big to allow for the variance of being hand built. YMMV. 

[TTaylor]

With window thickness you have three options, 1/8, 3/16, 1/4.  The original was 1/8".  I went with 1/4 and would not recommend it for side windows. The 1/4" is much stiffer and makes installation more difficult and weighs twice as much as the original.  If I was doing it again I would use the 3/16" for the side windows and 1/4" for the front.  The solar grey is great. You can see the results in my photo album.   It is not a difficult process, but takes time and patience.

I did deviate from standard and used Dow 795 sealant. It has held up well and you can pick colors to match your windows or paint.  It is modern sealant used for Windows in skyscrapers.

[Greg Ellis]

A few years ago I replaced the rear 4 windows on my 1963 C model.  It was not very difficult to do and really did not take too much time.  Paul Beck from Weep No More gave me a lot of advice on how to do this and helped me out tremendously.  As did Willmar Air Services.  (My plane was in Minnesota having the tanks resealed when it was discovered that the windows needed to be replaced).  It has been mentioned in various responses but I thought I would go through my experience with the replacements. 

Some simple equipment was needed to do this project.

1)      Phillips head screwdriver

2)      Denatured Alcohol

3)      Various cloths and wipes for clean up

4)      Sharpie pen

5)      Flamemaster CS 3330B-2 sealant (1 tube for each window and possibly 2 for the pilot’s side)

6)      Caulking gun

7)      Spare piece of window or plexiglass (cut to form a sharp scraper)

8)      New windows from source of your choice

Start the process by removing the interior pieces which is easily accomplished by simply removing the interior screws.  Once you have removed the interior pieces you will see metal clips that hold each window in place.  If it has not been done already, number these metal clips with a marker.  They have to go back in the same order and same spot as they were removed.  These clips not only hold the window in place but they will apply pressure to the sealant to make sure it spreads evenly between the window and the airframe.  Remove each clip and depending on how old the sealant is on the windows, the window can be pushed in from the outside.  Clean the sealant off the frame with a solvent.  I found that denatured alcohol worked very well and actually dissolved the old sealant.

Trial fit your new window and with any luck no trimming will be needed as was my case.  If you need to trim then special trimming bits can be purchased specifically made for these types of windows.  Once the window fits properly, mix the tube of sealant.  I did this by hand.  It was the most labor intensive part of the whole project.  Follow the instructions on the sealant tube.  It takes a lot of mixing to get the product mixed (about 70 pumps of the handle!!! After 4 windows I was exhausted).  I then used a simple, cheap, Home Depot caulking gun to dispense the material.  Dispense the sealant onto the airframe.  Be sure to use all the sealant in one tube for each window.  Press the window into place then replace the metal clips in their proper order.  The clips will help express out a lot of excess sealant.  After all clips are in place you can use the denatured alcohol to clean off any that may have dripped onto the upholstery, etc…  Replace the interior upholstery.  I waited 24 hours for the material to cure then I used the sharpened plexiglass scraper to make a smooth cut around the outside of each window to remove the sealant.  And you are done.

I cannot stress enough the importance of using a whole tube of sealant for each window.  When the windows are fitted, you will notice that in some areas there is a larger gap between the window and the airframe and skin of the airplane.  If these larger gaps are not completely filled they will leak.  The excess sealant fills in the larger gaps for a nice, tight seal.