You're the first one I've ever heard this happening to.
Did you use pliers to screw the threaded rod into the nyrod? Did the nyrod split maybe where the pliers gripped it?
I'm going to forward this info to Mark, who is the mechanical genius behind TufFlight. I've had countless combat gremlin type wings destroyed into confetti in my early days of combat, with pieces raining down like helicopters with elevons dangling by their nyrods, but the nyrods never broke! The servo arms usually broke first!
The air loads on the elevator and tail really aren't that much to cause a flexible plastic push rod to fail in either tension or compression. There must be a fault in the installation technique -- something you are doing differently than we do. We'll get to the botttom of this.
Please PM me with your phone # and we'll get in touch with you if that's ok.
thanks,
[email protected]