On Thursday, November 14, 2013 10:18:20 AM UTC-5, son_of_flubber wrote:
On Thursday, November 14, 2013 9:55:42 AM UTC-5, Evan Ludeman wrote:

On Thursday, November 14, 2013 9:28:52 AM UTC-5, son_of_flubber wrote:







The problem is that rope degradation is not recognized and defective ropes are used until they fail prematurely.





The rope requires a preflight inspection, just like our gliders and airplanes. If you aren't doing this, you are doing it wrong.





I thought it was obvious that "used until they fail" refers to the specific ropes that failed prematurely on tow. Are you saying that visual preflight inspection will detect 99.99% defective ropes before they fail in the air?



One problem is that ropes are not retired when they show "normal wear", and visual inspection is very subjective. I was surprised to see what is considered "normal wear" in AZ where the tow rope is regularly dragged through grit. The effects of grit sawing away at the fibers inside the weave of the rope cannot be seen from the outside.

So... is this operation experiencing rope failure without overload? In 27 years in the sport, I've never seen this. If I did see it I'd change my procedures.

At some of my favorite places to fly, a PTT at 50 - 300' has some significant risks, so we take launch prep fairly seriously, the tow plane pre-launch checkout includes a warmup flight, etc. We don't break ropes, we inspect them visually and service them before they get ugly. We have no need for an ASTM approved test program....