15 August 2016

Wiring: Aiframe Harnesses

Update 12-Sep-16:  Since I've had some questions about this, I wanted to clarify:  My left tail harness pinouts are the same as the one provided in the kit except for the trim power wires (pins 6 and 8).  The kit puts those on the right tail harness and keeps pins 6 and 8 open on the left side.  For the wings, only my 9 pin connector pinouts match those of the kit's.  My other wing connectors do not (the 12- and 6-pin).

To assemble the wiring harnesses, I first mapped out what I wanted in each connector.  Again, I believe wiring diagrams are too difficult to be read by humans.  I instead created what I call a "wiring map", which shows what lives in each connector's pin.  Circles indicate wire colors.  Dashed lines demarcate the corresponding instrument/device the wiring belongs too.  Examples of my wiring maps for avionics can be found in here.

This is the left tail harness.  It accommodates the ELT, pitch trim and nav/strobe light.  It uses a 12-pin Molex connector 0003092121 with male pins 0002092118 (18-22 AWG) and 0002092103 (14-20 AWG).  Though Van's original layout calls for the trim servo power wires to be on the right side tail harness (to accommodate Dynon and Garmin autopilot wiring), I placed them on the left side harness since I'm using GRT avionics.  My right side harness only contains the GRT autopilot pitch servo wires and is not shown.

Down below is the wiring for the wing harnesses.  Again, I departed from the Van's layout to accommodate my unique avionics setup.  The left wing has two harnesses and the right has three, the third for the autopilot roll servo.  

The left and right wings both have resistive fuel floats, landing and nav/strobe lights so one of their harnesses share the same layout.  That harness uses a 9-pin Molex 0003091094 with female pins 000209119 (18-22 AWG) and 0002091104 (14-20 AWG).  

Though both wings have capacitive fuel indicators and low fuel indicators, the left side has the stall warner, heated pitot and OAT sensor whilst the right side has both the roll trim (though I have not installed the roll trim, I included the wiring for it should it be installed later) and autopilot roll servo (the latter necessitating a third harness for the right wing).  So these remaining harness layouts differ.  They use the same 12-pin connectors and pins as the tail harness above and the autopilot roll servo uses the 6-pin Molex 0003091064 and 003092062 with the same female pins and male pins as the above.

Here are all the wires cut to size and laid out in a column for each harness, with their connectors (the roll servo harness wires are not shown).  Tail wires were cut to 12 feet.  Wing wires to 10 feet.

Below left, the pins are crimped, soldered and placed in the connector housing.  It's important to label the socket for each pin so as to reduce mistakes, lest you need the pin removal tool.

Below right, the tail harness wires are lined up and ready to slide into their 1/8" PET Expandable Braided Sleeving.  Sorry for the poor image, it was difficult to capture the subjects.  The sleeving is the black line on the right.  The chair in the background was used to hold down the harness whilst negotiating the sleeving onto the wires.  The roll in the foreground holding down the wires kept the assembly from coiling back up.

The completed tail harness.

The completed wing harnesses.  The right wing is the column on the left and vice versa.