Infinity Grip Junction Box

This blog covers the trim junction  box

Overview
The trim control and sticks require a significant amount of mixing of the wires at some point and doing this behind the panel would have possibly created a lot of cross wiring in a small area. It was decided to create a junction box on the starboard side and the point chosen were the cables supplied with the Infinity grips meet.

The most practical way was to use a series of 9 pin connectors installed into a ABS junction box sourced from JayCar.  

Installation
Once the switch assignment was decided the grips were installed onto the factory sticks. Slots were then cut at the base of the factory sticks allowing the cables to exit and be terminated at the proposed junction box. 

The top side of the factory stick was covered with two [2] layers of gaffer tape that was folded over into the inside of the tube to provide anti-chafe protection for the wires as they entered the tube. The tape also provided additional diameter allowing the Infinity grip to clamp onto the stick tube as its diameter is about 0.4 mm undersize. 

Note: The Infinity grip was clamped using the screws supplied with the grip 

Cable to junction box from pilots stick

Use of 9 pin RS232 requires a number of holes to be created and a suitable punch was purchased to allow a professional job.

Four [4] dual relays were next installed onto the case front panel and secured with a suitable screws with two additional screws installed as a positive and negative tie points.

Wiring junction box
Note: RS232 had to be installed on the outside to operate correctly due to
the wall thickness of the case and the red crimps are the commons for the wire groups

All the plugs were wired using 22 gauge wire in every colour that was available in the ship. Each RS232 has a specific assignment allowing single looms to be created back to the flap junction box in the passenger compartment and to the indicators located in the panel

Once a loom was assembled it was then covered with self closing braided wire wrap from Jaycar with each end secured using suitable heat shrink creating a tidy loom while providing additional protection when run through the aircraft with little weight penalty.

Cutting braided - heated box cutter blade and cut while hot
this welded the woven mesh

A number of circuits from the sticks like mike, boost pump and flap had to be commoned and this was achieved by inserting the three [3] wires into a crimp lug and after crimping cutting off the lug with the exposed end coated in silicone to prevent possible electrical issues in service.

Trail mounting of junction box
Note: Plugs mounted on outside of the box

Two 0.020'' 2024-T3 aluminium lugs were manufactured then drilled to take four [4]  5/32'' pop rivets each. Once completed it was pop riveted to the longeron using 5/32 x 7 mm pop rivets. Studs were used to mount the box as it was found that fitting screws was difficult without the seat in position so removal at a later date would be challenging. 

Comments
The 22 gauge was stiff when loomed and I would use 24 gauge wire with the biggest problem just converting the schematic into actual wiring  with the schematic beign updated to as built.

A wiring diagram is normally done before commencing this type of work in industry but I started by connecting the pins as numbered on the original schematic and this resulted in a illogical layout requiring a rework as shown in the current schematic with the cost in time.

This is so 1980's you can just hear ABBA in the background

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