One piece back window M20F

[CajunMooneyguy]

Do I have to have an STC to put a one piece back window in my 67 M20F? It doesn't really fall into the "major modification" category. Not structural, doesn't effect performance etc.... Maybe just a logbook entry? And is there a source for buying the plastic or will flat wrap Lexan do?

[TTaylor]

Not sure on the paperwork required yet, still in the planning stages. You will need the parts from Mooney for the change (about $248 about two months ago). The glass you can get from any of the plastic companies that make parts for Mooney's. Just order for a late Model F and Serial number with the one piece windows.

[Marauder]

Not sure on the paperwork required yet, still in the planning stages. You will need the parts from Mooney for the change (about $248 about two months ago). The glass you can get from any of the plastic companies that make parts for Mooney's. Just order for a late Model F and Serial number with the one piece windows.

Speaking of the Mooney factory, does anyone know how much capability they still have? Are they just supplying parts from an inventory or can they still fabricate components?

[Marauder]

That is good to know and hear. With the fleet aging, there is only so much that can be gotten through the salvage path.

[CajunMooneyguy]

Does anybody know what those parts look like? Specifications on them? If its a simple doubler I'm sure I can make my own parts "equal to or better than". Any idea what the windows cost? Is there a vertical steel tubing member behind the interior plastic panel?

[TTaylor]

The parts are a 90 degree bent angle of aluminum equal to the length of the window.  

 

Windows prices can be found here:

 

http://www.glapinc.com/Mooney/M20FG/m20f-1976.htm

 

Unless you have a very loose mechanic, buying the parts is much cheaper than the work involved to convince your mechanic and FAA your part is equal to originals.  The $248 price I quoted was for both parts (right and left) including shipping.  My mechanic is much happier that I bought the parts and any paper work will be much easier.  The value of your plane is tied to the details of the documentation.  Besides you are supporting Mooney and keeping them alive with your purchase.

[FloridaMan]

I think the one piece helps with the appearance. Here's my M20F:

 

[Marauder]

What cowl is that? Lo Presti?

[DaV8or]

I think the one piece helps with the appearance. Here's my M20F:

 

 

Actually, the cowl and windshield helps a whole lot more!!

[DaV8or]

What cowl is that? Lo Presti?

 

Yep.

[CajunMooneyguy]

Yep. You absolutely right. I thought that price was "each" and didn't realize it was so long. Money well spent! Thanks to all!

[hmasing]

Picked up my M20F last summer, and am interested in doing this to replace the two heavily glazed original back windows with one piece.

Can anyone who's done this help me figure out the steps involved?

Thanks!

[TTaylor]

1. You will need the stringer from the 1976 F for each side.

2. Remove the old windows.

3. Cut out the support between the windows.

4. Install the new stringers tying the three supports together.

5. Install the new windows.

My photo album has some photos from the process.

[TTaylor]

I did a search on the old thread.  

Parts Left Side  340285-007  Right Side  340285-008.

Plan ahead and get flush rivets on hand.

I recommend Solar Gray 3/16" for the replacement windows (LP Aero). I put in 1/4", but I would not go that thick again.

 

 

[Marauder]

I did a search on the old thread.  
Parts Left Side  340285-007  Right Side  340285-008.
Plan ahead and get flush rivets on hand.
I recommend Solar Gray 3/16" for the replacement windows (LP Aero). I put in 1/4", but I would not go that thick again.
 
 

Tim - are those part numbers for the stringers and are they available from Mooney?

Also, was the extra work involved in the 1/4” the reason you wouldn’t do it again? I talk to the two primary manufacturers of the glass and they said they could make the chamfer to fit the 3/16” grooves. Did you need to do that yourself?


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[TTaylor]

 

Chris, Those are the part numbers for the new stringers.  They go above the window and tie everything together.

The 1/4" is very stiff to work with. It comes pre-curved, but there is still some flexing to fit the plane.  Also, I don't think the extra weight is worth adding.  The original is 1/8" so the 3/16" is already 50% thicker.  If I was doing it again and on my own time I would use the 3/16" and route it to fit flush.  I don't think it makes any difference in speed, but I tend to be a perfectionist.  We were working in my A&P's shop in the middle of winter so we were trying to get it done quickly to free up space.  I had a little help from those on MS, but did not know all the details ahead of time.  Second time would be easier and I would know how to plan ahead for the steps involved.  I did deviate from standard by using Dow Corning sealant in bronze to match the windows.  Much easier to work with and much more modern material than the old two-part sealants.  

[Yetti]

I believe someone here used a tablesaw to cut the edges for a flush fit.   I would think a router might work well too.  Buy scrap to practice on.

[Captnmack]

Yeah..I bought the Formers from Mooney but yet to install and don’t expect anymore than just a logbook entry and W&B change.

[SheryLoewen]

LASAR Parts can help with that modification and the plastic frame.

[carusoam]

@GeorgePerry had done this window change on his F, a while back...

He posted many pictures of the process while he was getting it done...

Best regards,

-a-

[hmasing]

I've reached out to Lasar, and they do not have an STC, or part #'s 340285-007/340285-008 - who has an STC for this mod, and where do I get the stringers?

Thanks!

[carusoam]

Check with Mooney...

The factory updated parts when going from early F to later F and J...

That’s What makes this update so well appreciated...

If you go with rounded corners in the windows....

That’s another piece of sheet metal...

Getting the interior parts to match is the added challenge...

hardly noticeable from the inside though...

PP thoughts only, not a mechanic...

Best regards,

-a-

[Marauder]

1 hour ago, hmasing said:

I've reached out to Lasar, and they do not have an STC, or part #'s 340285-007/340285-008 - who has an STC for this mod, and where do I get the stringers?

Thanks!

I'd check with Mooney as well. They have a site page dedicated to retro fits. Didn't see this one list, but if you ask, tell them others are interested as well. Let them know our green money is just as good as that green money used to buy an Ultra. If I was Mooney, I would be all over the retrofit market.

https://cdn2.hubspot.net/hubfs/4147179/TECHNICAL PUBLICATIONS DOCUMENTS/Retrofit_Kits_new.pdf

[Igor_U]

1 hour ago, hmasing said:

I've reached out to Lasar, and they do not have an STC, or part #'s 340285-007/340285-008 - who has an STC for this mod, and where do I get the stringers?

Thanks!

 

 

There's no STC. Normally, this would be done as a field approval and my IA (years ago) used a sample 337 and letter from Mooney (stating there are no structural changes) to file 337 for the mod. Modification is basically converting to later, M20J configuration. IIRC, there were few factory M20F with large window and NO stringers but my IA wouldn't do that at the time. As structural design engineer, I wouldn't either.

Parts were ordered from LASAR who, at the time had them in stock. Those are 201 parts so Mooney should make them if you order them... probably pricey these days.

Interior frame came from LASAR as well but was thin and flimsy so I would go with window frame from Vantage Plane Plastic; their interior pieces are better quality but heavier. you would need windows as well and sealant.

Someone might argue it's not a major mod and 337 is not needed but good luck finding mechanic who'd just do log book entry; my IA wouldn't.

Regards,

[TTaylor]

No STC required, we did it under a log book notation.  There used to be a thread that had a letter from Mooney stating that there was no difference in structural strength. Your mechanic may prefer a 337.  I recommend not using the J analogy, but the 1976 F as the basis for comparison.  That will allow you to use the same model.  We ordered parts directly from Mooney.