Re: FAA To Finally Ditch Floppy Disks & Win-95

c186282 <c186282@nnada.net> wrote:

On 6/15/25 10:19 AM, Rich wrote:

c186282 <c186282@nnada.net> wrote:

On 6/14/25 12:34 PM, Rich wrote:

c186282 <c186282@nnada.net> wrote:

On 6/13/25 11:35 PM, rbowman wrote:

On Fri, 13 Jun 2025 22:38:38 -0400, c186282 wrote:
>
>

      In any case it's become very clear that a major update is needed for
      the US airport/routing system. Knowing the govt process, the stuff
      will already be obsolete by the time it's installed, but not nearly
      SO obsolete.

>
In the early '70s we had a contract to build the controllers for the ALS
system. The heart of the controller was an Eagle Signal electromechanical
stepping switch which was pretty much obsolete. The harnesses had to be
laced since the FAA wasn't sure about those new-fangled nylon cable ties.

>
    Ooooh ! Nylon ! EVIL !!!   :-)

>
Not so much that as: Ooooh!, we don't know how well this new "tie"
method will withstand extremes of cold, hot and vibration, and the
current regs.  specify "laced" and we *do* know how lacing withstands
extremes of cold, hot and vibration.

>
   Nylon has been around in quantity since the 40s.  Somehow I doubt
   it's qualities were 'unknown' in the 50s and beyond :-)

 
What's more likely is its qualities were well known, and known to be
unsuitable for use in aircraft wiring harnesses.
 

   MORE likely some senator was vested in a biz that made the older
   materials.

 
In your specific example of aviation wire looms, likely not -- see
below.
 

   There ARE circumstances where 'natural fibers' CAN outperform
   plastics - esp at very low temperatures where the plastics become
   more brittle.

 
And just what do you have at altitude?  Very low temperatures, just
exactly what you state "where the plastics become more brittle":
 
https://matmake.com/properties/standard-atmosphere.html
 
10k-20k feet -> -60C
25k feet (typical passenger aircraft cruse altutude) -> -50C

 
 
  You DO have a fair point here. Not ALL plastics get
  brittle, but maybe Nylon does. In any case I'm sure
  they're not using hemp string for aircraft harnesses
  anymore.

A little digging indicates that nylon's 'brittleness' temperature is
somewhere in the -50C to -60C zone.  So the typical temperature of the
environment is right in the "brittle zone" for nylon.  Then one has to
factor in the impact of vibration (which might cause a not yet fully
brittle nylon tie to shatter at -40C instead of -55C) and I think we
can see why nylon ties might not be aircraft rated.