This specific wire for military and aeronautical use is the evolution of the now obsolete MIL-W-5086 with PVC coating which, in addition to having a lower melting temperature, creates toxic fumes in case of fire, very dangerous for planes.
For some time now, the FAA Federal Aviation Administration has been compliant in the use of the unshielded MIL-M2759 (MIL-W-22759) which has advanced technical characteristics:
Tefzel coating (ethylene / tetrafluorbethylene) a Teflon-based plastic polymer that resists temperatures up to 150 degrees and up to 600 volts. This coating is also very resistant to rubbing and wear, ideal for the aeronautical sector where technical excellence almost never compromises.
Number of filaments higher than the average, this allows greater efficiency in the conduction of the current and also flexibility.
Tin plating of filaments which prevents oxidation and further improves usability in wire harnesses.
Competitive price compared to the advantages in its use, for a complete avionics system we are talking about a cost, compared to a common electric cable, of 30-40% more which has a negligible impact on the total cost of the aircraft.
Article in Italian on the M22759 standard
if you want to learn more, open the FAA attachment:
MIL-W-22759 Vertical Flammability Test Versus the 60 Degree Flammability Test