45A-04 Firewall Forward Harness

Despite the 1st instruction stating to remove the Top Skin assembly (to open up the avionics bay) I think I’ve gotten through the toughest part of the installation without having to do so.  I was able to snake the Firewall Forward Harness through the firewall penetration by taking all of the wires (except for the yellow wire to the regulator) and laying them into a length of painter’s tape and rolling up the tape to make a “smooth” shape to thread through the avionics bay wiring nest and out the firewall penetration.  I learned from previous attempts at this trick.  There are 3 connectors with bulky shapes that all terminate at the same length.  I staggered them in the tape trough and let the slack wire be at the proximal end, then later tightened them up.  

The power wiring harness has a very bulky (heavy gauge) wire that is actually bifurcated on its way to the regulator, and that needed to go through the inferior snap bushing below the avionics shelf (new location of regulator.) That was a pain to pass through the tightly packed snap bushing and I needed to remove the pitot line, pass the power regulator wires, and re-insert the pitot line.  

The instructions also imply that the pitot line (Aft Pitot Line to Pitot Line) gets spliced within the avionics bay, but mine was able to be spiced forward of the firewall.  I may have a shortage at the aft end (AHARS), but if so, I’ll just add a splice back there.  It wasn’t tough to slide the lines into the splicing tube, so I added two tie wraps for additional security.

 

Firewall Forward Harness

45A-03 battery wiring

Just the large gauge wires from the battery.  Note that the (-) terminal is open, as we don’t want any unexpected power flowing through the system!  I also had to remove the fuel ‘short circuit’ I built for fuel testing.  There’s a bit of blue tape over the open fuel lines to prevent any debris from entering.

 

Battery wires

45A-02 Battery, Relays

Not much fuss.  Build up a support bracket to hold down the battery and install the main relay and starter relay on the firewall. 

installed Battery, Relays

53-05 ADS-B supports

The supports for the ADS-B attach to the support for the Com radio.  For some reason, they are not mirror symmetric, but are actually the same on both sides.  Again, I won’t be installing the radios yet until the wiring is all done.  

ADS-B support brackets

53-03 Antenna (ADS-B) Doubler

Another ridiculously simple page.  Much of this chapter deals with doing an installation on a completed aircraft, so many of the pages and steps are not applicable to me.  In particular, this page only had one step that I needed to do.  It calls out for me to divide a pair of doublers, then discard one of them!

ADS-B Antenna Doubler

42C-09 AHARS stiffener

Some early members of the RV-12 fleet reported a vibration in the upper portion of the tail cone which played havoc with the AHARS which is located right back there.  It took about a year for Van’s to be able to get all of the data and verify, etc., and come up with a fix.  The horizontal structure you see at the top of the  cone (it’s reflected, so it looks like there’s two of them) is the fix.  It was relatively easy for me to install since the tail cone is wide open. 

AHARS stiffener

42C-07 GPS antenna

This page is slightly odd.  It calls out for me to dimple a plate, attach the puck, and then attach the plate to the shelf you see pictured.  Why the plate?  Why not just dimple the shelf and attach directly?  Oh, well.  There must be (or must have been) a reason.  The clamp-to-clamp arrangement on the engine mount was straightforwardly painful to try to get the two clamps together enough to pass the bolt, but not worse than you’d expect. The wires got passed into the avionics bay, inserted into a D9 connector and attached to the Magic Box.

Skyview GPS Antenna (puck)