Halyard Failure

[billknny]

Looking for thoughts on preventative maintenance for high tech halyards.

A bit of background. The boat is a J-105 in day charter service on San Francisco Bay. Used a lot (4+ days per week) and usually in our heavy winds (15-25 knots). The line in question is the main halyard, and I believe it was Yale's Vizzion of uncertain age, but more than 2 years.

We inspect the running rigging regularly, and have found that chafe has been a reliable indicator of need for replacement. Until now...

The halyard parted while hoisting the mainsail. Investigation found that it broke at the point where it is usually clamped in the rope clutch. There was no sign of external chafe or any damage to the cover at all, but... the line's core was totally crushed, and brittle with no tensile strength at all.

The scary part is that we had guys up the mast on this halyard three days before--with safety lines, of course, but still...

So my question... Is this something we should expect, but just have seen before? Should we put high tech halyards on a replacement interval irrespective of the physical inspection?