On Wednesday, January 29, 2014 3:36:56 PM UTC-8, Dan Marotta wrote:

So, what's the real test, Bob? Would simply giving it a good tug after
hookup disclose a failure? Or would it simply not close over the ring, once
installed by the wing runner? I have only a CG hook - wouldn't it suffer
the same failure mode?

I'm sorry, I don't know the answer to that one.

The one failure I was directly involved with was where one side of the spring had broken, but the other side was intact. The result was that the hook appeared to function correctly, but it sprung open as soon as the towplane powered up. JJ can probably tell you more about this.

Bob K.