sisu1a wrote:
studies have
shown that 20 yrs of normal use/exposure is approaching the safe
working life limits of the materials.

That's not what Strong parachute says, or my rigger, so I'd like to see
these studies for myself. Do you have a link to them?

Eric Greenwell - Washington State, USA


I do not, I was passing along hearsay from a trusted source, and after
searching the best I could find was this article on the subject form
1958, http://tinyurl.com/6b5bca (.pdf file...) which admittedly does
not really support my point much being as old as it is. After talking
with a prominent rigger today while I was picking up my National, I
asked him about it to find the answer so I could provide such data. He
could not point me to any sources either, although he of course agrees
with the 20 yr thing. His suggestion was to ask some higher ups at
Parachute Industry Association, which I have done, and I will share
anything I turn up from that avenue. Also, here is a link to the PIA
rigger's newsgroup, where I'm sure you could get more useful info
there if you are motivated enough on the subject to post/search the
http://www.websitetoolbox.com/mb/rig...ool/mb/riggers

Mostly, I'm puzzled by the idea that an emergency parachute has a
"working life limit" because it doesn't work: it just sits there. I
would think it's only a matter of how long the materials last, and nylon
and metal will last indefinitely in a cool, dry place.

Poor choice of wording on my part I suppose. I didn't mean time spent
'working' when I posted that, but rather the length of time it is
still fit to work if it needs to. According to the same rigger, the
older nylons (like what would have been used in the 1958 study linked
above...) actually held up longer than the newer materials, but was
lower performing in actual use. Much like today's high performance
optics, today's high performance parachute materials have special
coatings that affect the physical properties and such, but on chutes
they supposedly degrade and rub off over time, even under the best of
conditions. 20 yrs is even thought to be optimistic to some for this
reason...

-Paul