Windshield issue

[4RNB]

My plane was originally to be painted a long time ago, numerous delays occurred. I purchased all new glass/plastic for the winders, stored them around the house and then took them to the paint shop a couple months before painting was to start. This week when they were unwrapping the windshield they noticed crazing. Too late to file a claim, original supplier is offering 50% off replacement, but they do not yet have raw materials in place. Supplier said they'd been seeing a lot of this, perhaps blamed freight lines for stacking things on top of the box.

Anyone experience this?
Any thoughts on the matter?
Would a crazed window offer value to anyone else?

 

[Dan Thomas]

That would appear to be from a poor heat-forming process, if it's just at the tightly-bent areas. The stress of bending too-cold acrylic will start microscopic cracks that grow and show up later. I'd go after the manufacturer, after looking at the rest of the windshield to see that the crazing is limited to those tight radii.

 

[4RNB]

That would appear to be from a poor heat-forming process, if it's just at the tightly-bent areas. The stress of bending too-cold acrylic will start microscopic cracks that grow and show up later. I'd go after the manufacturer, after looking at the rest of the windshield to see that the crazing is limited to those tight radii.

Maybe so, but it has likely been in the box for over a year.

 

[Bell206]

Any thoughts on the matter?

Have to agree those defects look more like poor fabrication than crazing due to age or heat/chemical causes given how pronounced the lines are.
While stretched acrylic doesn't handle extended storage cycles I would not expect to see that much damage within a year unless stored improperly. And even then its a reach.
Given the time frame I'd pursue the 50% offer but inspect the replacement when received and if any similar marks can seen no matter how small I would hit the supplier for a 100% on the original.
My guess there is a reason their offering you 50% to begin with.

 

[Gary Ward]

My plane was originally to be painted a long time ago, numerous delays occurred. I purchased all new glass/plastic for the winders, stored them around the house and then took them to the paint shop a couple months before painting was to start. This week when they were unwrapping the windshield they noticed crazing. Too late to file a claim, original supplier is offering 50% off replacement, but they do not yet have raw materials in place. Supplier said they'd been seeing a lot of this, perhaps blamed freight lines for stacking things on top of the box.

Anyone experience this?
Any thoughts on the matter?
Would a crazed window offer value to anyone else?View attachment 124321View attachment 124322

I agree that did not come from improper storage or shipping damage. Sucks
What's the rest of the window look like?
I guess you should try the same supplier for 50% off and inspect right away.
Otherwise I would go with a different supplier. Sorry about your trouble.

 

[Dan Thomas]

Maybe so, but it has likely been in the box for over a year.

Those things are installed in airplanes for 40 years and more without crazing. Cold, hot, wind pressure, prop blast vibration, too. What stresses do a box put on it?

 

[4RNB]

Those things are installed in airplanes for 40 years and more without crazing. Cold, hot, wind pressure, prop blast vibration, too. What stresses do a box put on it?

Manufacturer suggested shipper putting something on top during shipment.

 

[Bell206]

Manufacturer suggested shipper putting something on top during shipment.

Doubtful in my experience. If it was that much force the box would be broken or the window would.

Those things are installed in airplanes for 40 years and more without crazing. Cold, hot, wind pressure, prop blast vibration, too. What stresses do a box put on it?

FWIW: Years ago I was told by a Great Lakes or Tech Tool rep that uninstalled stretched formed acrylic windows can craze while sitting in storage due to normal ambient condition fluctuations. Once installed that storage craze mechanism changes due to all edges are now secured and "rigid." Its also a reason its common practice not to keep more completed windows in stock than can be consumed in a certain period. Even at my old day job we didn't keep certain acrylic windows in stock due to this issue. Regardless, this type craze doesn't happen over night either.

 

[Dan Thomas]

Doubtful in my experience. If it was that much force the box would be broken or the window would.

FWIW: Years ago I was told by a Great Lakes or Tech Tool rep that uninstalled stretched formed acrylic windows can craze while sitting in storage due to normal ambient condition fluctuations. Once installed that storage craze mechanism changes due to all edges are now secured and "rigid." Its also a reason its common practice not to keep more completed windows in stock than can be consumed in a certain period. Even at my old day job we didn't keep certain acrylic windows in stock due to this issue. Regardless, this type craze doesn't happen over night either.

The Cessna windshields aren't mounted rigidly. The airframe around the windshield flexes too much. Even engine torque distorts it, and you can hear the windshield shifting on startup and shutdown. The windshield gets felt tape on all its edges and slides into a slot along the cabin top and slots down the front doorposts and then the curved bottom strip and wing root fairings are reinstalled to keep it in.

The pressurized Cessnas are different, of course. The airframe is much stiffer and stronger to take the pressure, and windows are sealed in.

 

[Bell206]

The Cessna windshields aren't mounted rigidly.

What stresses do a box put on it?

I was merely replying to your box stress question by forwarding some relevant info given to me by people who actually produce acrylic windows. Nothing more. I’m also rather familiar with how various aircraft windows are installed, hence my use of “quotes” around the word “rigid.”

 

[4RNB]

I appreciate the installation comments as the install shop is wondering if the windshield needs U channel. What I've learned is that the windshield gets some type of felt (there are several widths) and some of the side windows get rubber U channel.

 

[Dan Thomas]

I appreciate the installation comments as the install shop is wondering if the windshield needs U channel. What I've learned is that the windshield gets some type of felt (there are several widths) and some of the side windows get rubber U channel.

The aircraft's service manual has all the information on it. That windshield should also have come with that information. If the windshield isn't properly installed, it will fail.

 

[4RNB]

The aircraft's service manual has all the information on it. That windshield should also have come with that information. If the windshield isn't properly installed, it will fail.

Thanks. You make a good case to ask around about how to do it...

 

[Magman]

This is not a learn as you go task.

I don’t believe you stated of Aircraft so there are different configurations.

Center Windshield Strip? If not, there are clips on the top edge.

The lower edge has a 2 inch wide strip to deal with.

There are folks that you can make the change w/o removing it.

I‘m not in that camp.