Windshield Install Questions

[reecewallace]

I've just removed my old scratched windshield to install my new one piece windshield. Photo https://www.pinkbike.com/photo/27512708/

I removed the strap from the old windshield, drilled out the top rivets holding it in place, and removed all the screws & nuts along the bottom of the windshield.

Now it's time to install the new windshield! Questions for everyone.

1. I need the following, but can't find any p/n's because they're not listed in the IPC.
*Several mechanics I spoke with recommended using stainless hardware instead of rivets.

Top screws: 6/32 x 3/4” stainless
Nuts: 6/32 stainless nylock
Stainless washers

Bottoms screws: 10/32 x 1/2” stainless
Nuts: 10/32 stainless nylock
Stainless washers

Screws must be structural?

2. What type of silicone is suitable to seal the new windshield to prevent leaks?

[cessnut]

I personally don't like the look of screws in the lower windshield retainer. It's not that difficult to install rivets. In fact it's faster than standing on your head installing washers and nuts.
I can tell you for sure that no silicone is suitable for sealing a windshield. Silicone lasts forever but it does not stay adhered over the long haul.
While you have it apart inspect the inner retainer for corrosion at the lower corners.

[GAHorn]

Do NOT use “silicone” (RTV) to seal plexiglas/acrylic/poly/etc. It off-gasses ammonia and wil embrittle and craze the plastic.

If you feel the need you might use butyl tape or even-better, chromate-putty/tape (like found in a lot of Pipers ….pittuit…pittui …(had to spit that out)

The windshield should “float” in a strip of Felt. The felt will quickly wick-away any moisture. I’ll try to find that Cessna guidance article on this subject….but Gary will probably beat me to it.

(I seem to recall MIles did a good article on WS installation….you might find it in past issues of The 170 News.)

[cessnut]

Felt tape, zinc tape/putty if you can find it. I use felt tape as prescribed by the windshield mfr., strip caulk, and PRC. After it is all installed I tape it off nicely and apply an edge seal of AC-251.

[ghostflyer]

Reece,
Firstly ,I would follow what the manufacture instructions has placed in your box /web site regarding windscreen refittment . I have used both of the popular brands and both refittments are different . I would consider very carefully of not refitting the center strap. I think it was Lakes that stated that in their fitting instructions that it was optional but will weaken the windscreen. The bolts and nuts for top of the screen was supplied by manufacture and please do not dig out or remove the inserts that have been bonded into the holes already drilled in the windscreen . Felt must be used in the sides of the windscreen attachment to the fuselarge but use the “grease” on the felt supplied by the manufacture. There are RTV,s out there that doesn’t release harmful by products . I have used floating nut plates on retaining my windscreen to the fuselarge . I do them in 8 gangs of nut plates together. riveting puts too much localised stress on the area. And it stops “Ops” the rivet gun slipped off and hit the new screen. IT happens , I saw a owner do it twice [2 times] to different screens . You can’t repair a screen easily on a curved area . It was a beautiful dummy spit.
TIP. use 2.5 in gorilla tape over the tails of the rivets that are already in place that’s holding the old screen in. The tails will not [and swarf] will not drop in on your instruments and electrical wiring when drilled out.

[dstates]

Here are a couple images from the Cessna 100 series service manual calling out Presstite 579.6 sealer. I only used it for the for the bottom of the windshield.

windshield_2.jpg (35.39 KiB) Viewed 2055 times

I think I purchased it from LP Aero who I also purchased my windshield from. I remember it being a bit pricey.
Listed as strip sealant on this page:
https://lpaero.com/accessories-catalog/

Here is more discussion on it.
viewtopic.php?t=10005

[cessnut]

If you are in the habit of letting your rivet gun slip off you probably should not be undertaking a windshield replacement. Just saying...

[falco]

Rivnuts and screws work well too.

I don't know how much work it saves -- I did that 23 years ago and I am still a long way from needing to replace the windshield.