Richard,

What Cat 5 cable are you using? The stuff I deal with (plenum or non-plenum) is all solid wires and would be prone to vibration damage I would think? For what it's worth, I've wired up a "custom" wiring harness in a F-82 twin Mustang using some multi-conductor shielded wiring from Belden. Lot's of stock stuff available with & without shielding. Has held up real well, & sure beats dragging a bunch of individual extension cords thru the center section of the wings.

Bob