From Wiki:
"Death of Michael Lush
On 13 November 1986, self-employed hod carrier Michael Lush was killed during his first rehearsal for another live stunt. The stunt, called "Hang 'em High", involved bungee jumping from an exploding box suspended from a 120 ft-high crane. The carabiner clip attaching his bungee rope to the crane sprang loose from its eyebolt during the jump. He died instantly of multiple injuries, and the Breakfast Show was cancelled on 15 November after Edmonds resigned, saying he did not "have the heart to carry on".[7] Rumours, denied by the BBC at the time, that Edmonds had been due to resign to launch a career in American television proved incorrect."
(Noel Edmunds Show)
I know personally of another incident when a crab failed on a zip wire at about 30 mph. The unfortunate victim is happily alive and well but was well busted up at the time. I wont kname him but some on here may know him.
I trust 10mm maillons and struggle to visualize any condition where one will fail. I am however aware of the situation with Pezl Stops where the use of one can cause the gate to twist undone.