Saturday, March 26, 2016

Autopilot Disconnect Switch Readied for Instillation

After doing a little more dressing of the wiring in the instrument panel, decided to do a little prep work on the autopilot disconnect switch. When fabricating the separate mounting bracket for the controls, the mounting hole for the AP disconnect switch was not drilled. At the time, I was planning on only using one of the switches on the Tosten control grips to disable the autopilot. However, have decided to go ahead and install the AP disconnect switch for a couple of reasons … one being the control panel will conform to other RV-12’s and by having the AP disconnect switch installed, it will be a convenient location for wiring the autopilot disconnect wire from one of the switches on the Tosten control grips.

When installing the optional AP Panel module, the Autopilot connector on the AV-50000A Control Module is replaced by a new wiring harness that comes with the AP Panel kit. The white F452 wire from that harness is the autopilot disconnect wire and is attached to pin 1 of the Molex connector for the AP disconnect switch. Pin 2 is the black ground wire for the switch. Pin 3 is the yellow/purple cockpit lights power for the internal LED in the disconnect switch and pin 4 is the yellow/green cockpit lights – wire for the LED light. When the AP disconnect switch is pushed, the switch places a ground on the white F452 autopilot disconnect wire … so this will be a convenient point to attach the autopilot disconnect wire from the Tosten control grips.
The autopilot disconnect switch. Pressing the AP disconnect switch places a ground on the white wire which trips the autopilot off. … this will be a good wire to mate with the autopilot disconnect wire coming from the switch on the Tosten control grip.
The white wire in my hand is the F452 autopilot disconnect and will be wired to pin 1 of the Molex connector.

The female .093 Molex connector pin on the white F452 wire was cut off and replaced with a new female pin along with the addition of the AP disconnect wire from the Tosten control grips. The two wires were both crimped onto the connector pin and will be inserted in position 1 on the Molex connector. When crimping the connector pin, I was not able to see the wires in the connector and discovered the yellow wire pulled back a little and the strain relief did not capture the insulation on the wire. Decided to use a tiny piece of heat shrink tubing on the wires to aid as a strain relief. Plus all the wires will be snugged together with wire ties so adding the heat shrink was probably unnecessary but makes me feel a little better. The overall diameter is small enough that the heat shrink should not interfere with inserting the pin in the Molex connector.
The yellow wire is the AP disconnect wire from the switch on the Tosten control grips … that wire was crimped along with the white F452 AP disconnect wire. This pin is now ready to be inserted into position 1 on the Molex connector for the AP disconnect switch.

The AP disconnect switch requires a 1/2" hole drilled into the mounting bracket for the controls. Typically, the center panel section has a tiny hole that gets enlarged to 1/2" when the auto pilot is installed. In my case, the DOG Aviation RV-12 uses a modified separate mounting bracket for the controls, so needed to make my own hole by drilling a lead hole then used a step drill to enlarge the hole to 1/2" to accept the AP disconnect switch.
Using a step drill to create a 1/2" hole in the controls mounting bracket for the AP disconnect switch.
The AP disconnect switch temporarily installed in the newly drilled mounting hole … it fits.

Readers may be wondering what the blue tape with the red marks is being used for. While working with the mounting bracket for the controls, each one of the controls was test fit into its respective hole (after some powder coating was filed away from each hole) so measurements could be taken to determine how much room is taken up by the mounting hardware. Measurements were made to determine how much space remains for engraved labeling. I was so pleased with the way the labeling turned out for the fuel pump and landing light switch that the decision was made to make similar engraved labeling for the controls as opposed to stick on labels ... so measurements were taken and drawings were made for the engraver.