Having worked with a lot of molded plastic parts I agree this is a stress failure. But why?
I notice Cub is using self tapping screws to hold the hood onto the hinge assembly. It's not the best way and most that use molded parts won't do it on any assembly that's stressed. The screws put too much stress on the boss they screw into, or alternately can't provide sufficient clamping force unless the hole size and assembly torque is exactly right. And if wrong you can get thread stripping, or cracks in the boss like we're seeing here. Either way the assembly will fail.
Even when you get everything right the overall assembly isn't as strong as one that uses a threaded insert and machine screw. Too much stress, too many ways to put it together wrong with a thread cutter.
In the case of the these failures though it's hard to tell specifically what happened.
Hinge was moved too far at some point, or moved with some of the fasteners loose or missing? Improper assembly of the hinge? Poor molding of the hood and hinge attachment area? Hood material losing some of its mechanical properties because of elevated temperatures? It doesn't matter though does it? All of these things point back to Cub since it's highly unlikely 2 posters caused an identical problem on 2 different tractors. It also makes it less likely it's just a fluke or random occurrence.
I think we all know the "advantage" this hood assembly provides and why it was done. The $$ advantage to Cub.
I still think it's possible to make one that works just fine. I wonder, do we hear JD and Kubota owners complaining about theirs? I wonder too how much of that money Cub saved will in turn fall into the pit of warranty claims. Not to mention the long term cost of customer dissatisfaction.
What Cub does about all the hood issues will tell a lot. If they fix these things promptly and modify the product to eliminate these problems in the future I say good on them. If not, and they adopt the automakers technique of starting to deny warranty claims to cut warranty costs, then I say good luck to them. There's bunch of people in Detroit and elsewhere that can tell them how that'll work out in the end...
