Catastrophic or sudden shaft packing failure

I'm doing a little research on a failure that I came across. Not an Ericson but hopefully worthy of discussion by this educated forum (a little suck up never hurts ).

Has anyone on this board ever experienced a catastrophic failure of their "traditional" stuffing box (wax impregnated flax)? Not just wear and an increased drip rate but a rapid increase of water flow beyond what a "convenience" small capacity bilge pump would hande.

The scenarios I could think of are possibly the lock nut coming loose, the packing nut then backing off and the packing blowing out. But in the boat this happened to they found it low in the water. The yard replaced the packing but didn't mention anything like a failure of the nut.

Of the five packing rings, two are modestly worn but generally intact, the third is damaged and the 4th and 5th are torn up but that may be a result of removal.

I helped bail out a boat that had the packing nut back off when it was put in reverse. An amazing amount of water can enter in short period of time. I don't think most bilge pumps would be able to keep up with it.

I put a small hose clamp on my shaft just forward on the packing nut so it can not back off far enough to let in a large quantity of water.

It's tough to imagine how flax packing can really go too far wrong very quickly when it's stuffed in there and held together by the nut. Loosen or lose the nut, though, and it isn't so hard to imagine any more.

I have a zinc (rather than a hose clamp) installed on my shaft on the inside of the boat just forward of the Lasdrop shaft seal to ward off this kind of catastrophe.