In reply to woollardjt:
> No spring leash is designed to hold a fall,
> they are just designed to stop you dropping an axe. Some folk have fallen and they have held others not.
I don't disagree with that at all.
Certainly no manufacturer would ever say they would hold a fall.
But in reality I have witnessed and experienced them to hold falls, including a hard one (the leader well above the tool).
A friend of mine was using a 4mm cord to connect the lanyard to the axe, and in a leader fall, the cord broke, while the lanyard was OK. The breaking strength of 4mm cord is roughly 4kN or a bit less, which means it is a lot stronger than 4kN as a loop. I have no idea if the cord may have caught the metal edge or was already damaged, but the point is the lanyard was actually pretty strong at least in that case.
Black Diamond Spring Leash system seems to be rated as 2 kN. Although 2kN is pretty weak, considering its massive elasticity, I take it has a good chance to arrest a fall, IF and only IF the placement stays.
After all in most of the times, the fall factor would be very small - your tool is likely to be above you.
I totally agree you should never trust the lanyard to take any fall. But in reality it is I found very nice to have a potential backup - a bit like having a RP pro at sharp end in rock climbing. Massively better than nothing.
Masa