Bottom line:
The wires are not the current limiting factor, it's the D connector's pins. Could be conservative from a current standpoint when Dynon uses two pins for power and ground to Skyview Display but no second-guessing the Dynon install manual.
From a voltage drop standpoint the second wire is needed to meet AC 43.13-1B.
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Some details:
The red and black power wires in the SV-HARNESS-D37 are 22 awg, specifically M22759/16-22. 22 awg is conventionally good for 5A based on 10C temperature rise not in a bundle.
D connector pin/sockets are nominally good for 5A unless they are heated by nearby current-carrying pins which could be somewhat of a consideration because all four subject pins are adjacent on another in this case, 1, 20, 21, and 22. There may also be considerations for the foil on the circuit board or other aspects inside Skyview display.
Per the install manual, Skyview display draws 2.4A. Add items powered over Skyview network like GPS puck, ADAHRS, AP panel, EMS, ARINC, knob panel, SV Bat, USB video, USB WiFi and you could conceivably be up to 4-1/2 A.
As for voltage drop, suppose the harness is 5 feet long, round trip of power and ground is 10'. With two 22 awg wires the voltage drop is 0.36 V which is under the 0.5 V recommendation in AC 43.13-1B.
- 16.1 Ohms per 1,000 ft, 10 feet, 4-1/2 A gives 0.72 V. Parallel the second conductor and it's 0.36 V.