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Lexan/Plastic Lower Door - Need 337!

sj

Staff member
Northwest Arkansas
Hi Folks!

The local AI will cover the lower door with lexan, but would like to have a copy of a 337 field approval on such a modification before trying to submit it here locally.

Anybody got one they are willing to share?

My fax number is 816-741-5212

MUCH APPRECIATED! :eek:

sj
 
I did get this issue resolved, he signed it off a while back. Thanks!

sj
 
One warning about Lexan, anywhere mosquito repellent touches it, it will cloud up. I suspect it is also susceptible to damage from other mild chemicals.
 
Plexiglass is subject to the same problem! I had a guy thinking he was doing me a favor and sprayed "off" bug dope in my 180 and ruined $2000 worth of plexiglass!

Tim
 
Lexan vs plexiglass

When I rebuilt my J-3/PA-11 a few years back.........I was told to use Lexan that it was better..........then I was told not to use it........because avgas will cloud it. I pour avgas on a scrap piece and nothing happened....even let it sit for a long period of time....and put more on it.........nothing ever happened. As for scrathcing easier........I didn't find that was the case either.........they both scratch. I do remember that the place I purchased the Lexan...told me that was a brand name.........and I can't remember the technical name for the glass.....but maybe there's different manufacturers of .......what we are all calling lexan.......and some is not as good as others........I would suggest a test and see. That was my experience. By the way......I have a friend that installed saftely glass on the left side sliding window............and no.....it's not approved, but doesn't scratch easily either...........Happy and Safe Flying "Brian"
 
Heck I saw a Fairchild the other day that had Factory Safety glass with roll up windows? I thought, why not make roll up windows in a Cub? there is lots of room actually and a modified/ copied window regulator like a car would be pretty easy to fashion? I am going to the drawing board?

I would love to know more about the "quality" of Lexan, and same with Plexiglas?

I hear in Texas they just take the dern think out and throws it away when it gets all scratched up?

Tim
 
Yep, finally got tired of putting them back in and got 'em fixed, by a pro. Haven't blowed 'em since. Sure is hot in there now. :p
murph
 
In our spray planes, we are constantly flying back through lots of different chemicals. Many contain ethylene and other compounds that really play havoc on plexiglass windshields and side windows, especially if not removed pretty quickly. Once in a while I, or one of my pilots forget to clean it upon landing and it etches the windshield. We have had good luck with polishing it out with MirrorGlaze or even Dupont #7. We have to do this fairly routinely so we can keep seeing where we're going at 150mph at a nosebleed altitude of 2-3 ft.

murph
 
If I use Lexan for anything, I specify mar-guard Lexan, which is coated so the surface won't craze and get milky. The best testimonial I have is I used it for boat windows on the Susitna and Yentna rivers, they were always getting blasted with silt, and they always cleaned up like new. I'm using it on my 12 doors now.
 
Lower door covering

When putting lexan/plexiglas in the lower door half is it just done to the outer face or the interior side also? just looking for a consensus. Jeff
 
Lower Door

You just put it on the outside. This is a mod I've never been fond of. Noisy, all the latching mechinisim inside the door is visible (ugly), heavier then fabric, breaks up the outside and inside paint job (stripes), another window to clean and get scratched, I don't sit that low. Ya, I know it's for your passanger - It's my plane and they're just along for the ride. Crash
 
If you use Lexan use MR 5000 it cost twice as much but will not scratch.
This is what race cars are using. It will not take much of a bend as there is
a hard coating on both sides. It works fine for doors and side windows. It will cost around $200.00 for 4x8 sheet. It goes by different names depending on who makes it.
 
I've got the MR stuff for a skylight. It's what I used to replace one I "broke". Another story, just remember that when landing on a knife-edge ridge top, a strong crosswind is also a wind from underneath the tail.

Lexan with MR is extremely scratch resistant, avgas-impervious, and can be bent in a bending-brake.

The MR coating must be somethin' special, cause everyone who uses "regular"(?) lexan says that avagas attacks it, and it scratches easily.

Dave Calkins.
 
SJ,
did you get a copy of a field approval for the lower door or did your mechanic succumb to your overpowering logic and good looks? My mechanic feels the local fsdo is "after" him and does not want to accept plexi lower.
Riley
 
Not sure Bob, I think the Pittsburgh fsdo put my mechanic through a meat grinder for some personal reasons and he is very careful. Point of fact our mechanic has kept several people flying in our local economic malaise and the feds do seem to be a bit zealous in their interest in his activities. Of course personalities have nothing to do with official decisions. He would like to get a former field approval 337 if someone has one otherwise I will have to recover the lower door.
 
Easy solution: two doors, one covered and one Lexan.

We have a couple Super Cubs with Lexan - I will check to see if the one done by an FAA guy got a field approval. I fly often, but the door is almost always open. I never really notice the difference, Lexan or fabric, when closed, and I am usually in the back seat. I do appreciate L-4 and L-21 windows, though.
 
Steve,
I am going to try that route with my mechanic and see if I can reason with him. Your quote from Will Rogers is a classic, another of his I love is " Good judgement comes from experience, and most of that comes from bad judgement." What a great guy that makes you feel not quite as dumb for some of our less experienced booboos.
Riley
 
Did you ever figure this out? Just bought a cub and am repairing the hinges. Would like to go back with plexiglass. Thx
 
Hi Folks!

The local AI will cover the lower door with lexan, but would like to have a copy of a 337 field approval on such a modification before trying to submit it here locally.

Anybody got one they are willing to share?

My fax number is 816-741-5212

MUCH APPRECIATED! :eek:

sj
This still a good fax number? I got a document I need to send you. :lol:
 
Aren't they all like that - the clear lower panel? Some put double sided to keep frost free in winter from dog breath.

Gary
 
Mine has fabric. So do I need to worry about STC, or is it a minor repair? Also, I was looking at pictures. Hard to see what fasteners you are all using. Thanks for any help!!
 
Mine has fabric. So do I need to worry about STC, or is it a minor repair? Also, I was looking at pictures. Hard to see what fasteners you are all using. Thanks for any help!!

Yes, it's a minor. Different fasteners have been used. I like aluminum pop rivets with large area heads or over washers. Oversize the holes in the plex to allow for expansion.

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