Chapter 22 - Electrical System

The avionics and electrical system on this aircraft is a massive undertaking.  I do not think it is an exaggeration to guess that there are miles of wiring and thousands of interconnects.  I believe there are 12 antennae in it total (two nav, two comm, one marker beacon, one APRS, four GPS, one transponder, and one ELT)

The basic architecture is a glass-panel instrument panel with redundancy of every critical instrument for IFR flight.  The implementation is a Garmin G3X two-display system for the MFD & PFD.  The adio stack is a PS Engineering PMA9000EX audio panel, a Garmin GTN650 GPS/Nav/Comm, a Garmin SL-30 Nav/Comm, and a Garmin GTX330 transponder.  A TruTrak GX Pilot interconnects to the G3X system for autopilot duties.  An electric Falcon attitude indicator and a Taskem Altimeter/VSI are backup instruments.  

This shows the original GNS430W, which was later traded out for a GTN650.  Wait to buy those avionics until the VERY last minute.  Something newer and shinier is right around the corner!

The instrument panel is a 0.063" aluminum overlay.  It was trimmed to fit the composite panel, then all of the instrument cutouts were water-jet cut.

It was all done in AutoCAD for the layout.

Then printed full size.

Individual prints of the instruments at scale allowed me to move them around with tape.

 The aluminum overlay was roughed out with the bandsaw, then trimmed to fit exactly with a patterning bit on a router.

 All of the instrument cutouts were done on a waterjet cutter.  By the time you are done there is not a lot of material left.  The stiffeners top and bottom are left uncut to keep some structure in it.  

 The radio rack was done by hand with drills and a jig saw.  I later did one for another builder using the waterjet cutter.  That is the way to go.  Tying the instrument panel to F-28 makes a very stiff box structure.  

 Here is the instrument panel after it came back from Milner's Anodizing.  It is beautiful.

The N753CZ, the standard passenger warning text, and some other wording was done by a laser engraver.  All of the rest of the engraving is also done by laser, but on the components, not on the instrument panel.  Notice the bezel that pulls the GX Pilot autopilot to be flush with the faces od the radios and the Contura switches.  This is aesthetically much better, but it was done for another reason.  The TruTrak documentation doesn't tell you that the connections on the back add at lest 1/2" to the depth, and the result was the canopy interfered.  Moving the face forward was a big PITA, but it looks better and works.  Yet another little SolidWorks CAD, CAM, Anodize project that took hours and hours.

All of this created an electrically-dependent aircraft, so reliability and redundancy in the electric system was a must.  Dual Odyssey PC-680 batteries are charged by a B&C 60A alternator.  I also have a B&C SD-8 backup alternator, but it is not installed right now.  There is a battery contactor for each battery, a starter solenoid, and various insulated bulkhead fittings for the alternator and starter connections, plus a forest of tabs with a through-stud for the ground.  The space on the cold side of the firewall above the spar gets very full, very fast.  The last box is the Lightspeed Plasma III ignition system.  I tried very hard to make every screw penetration hold something on both sides of the firewall to keep it less cluttered.

A Vertical Power VP-X pro also interfaces to the Garmin G3X and provides all of the switching and circuit protection.  The VP-X Pro ended up on the passenger footwell on a tray very much like the one on the pilot side that holds the Garmin G3X AHARS.  Because all of the switching is software updated, I did not want any labeling on the panel for switches.  I chose to use Carlin Contura rocker switches and laser etched and painted each of them for the intended use.  This took WAY more hours that I would ave guessed, but the results are truly professional looking.