I want to make sure I know everything that's going on both sides of the firewall (and what's not).

Here are the two firewall-related diagrams from the manual:

On the engine side I know these won't be installed: TCU, Turbo Servo and RDAC (I believe that's an MGL box).  On the cabin side these will be additionally installed: TCU and Turbo Servo.

So, given that, I understand the following are the items on the engine side:

• Fuel Pump
• Oil Tank/Bracket
• Brake Reservoir Bracket
• Overflow Bottle/Bracket
• Battery Box (I have my own for my Li battery)
• Starter Relay
• Ambient Pressure Sensor (what's this for?)
• Cabin Heat Splitter Box
• Missing Anything?

On the cabin side we have:

• Regulator
• TCU
• Turbo Servo
• Cabin Heat Inside Cover
• Missing Anything?

Cables, wires, etc. that pass through the firewall:

• Brake Line
• Fuel Line
• Fuel Return Line
• Throttle Cable (manual shows 2??)
• Engine Choke Cable (manual shows 2??)
• Heater Cable
• Engine Monitor Cable Harness
• TCU Cable Harness
• Turbo Servo Harness (?)
• Electrics Earthing Cable
• Missing Anything?

I'm not clear on how the Cabin Heat Inside Cover gets attached.  It's not clear in the manual what's riveted and what should get rivnuts.

Any comments on the above??

Just a quick half hour.

Riveting in the sub-panel.  The two rivets in the center here were 3.2mm, but the holes got enlarged a bit when I drilled them out, so I upsized them to 4mm.

Doing a test fit of the front top skin.  Strategic cleco'ing was called for...  Trying to cleco the skin to the sub-panel from the side skin up was not going to work because it was too far off.  Starting in the middle down toward the side skin worked much better.

Cleco'ing the front of the top skin will also require some strategic cleco'ing.... Has to get through 4 layers of metal... :-O

Looking good.

3.5 hrs. finishing the sub-panel.

I decided the rear brackets I was making for the VP-X weren't going to do the trick, so I switched to using spare channel material I had.  Starting to fabricate the brackets.

One done!

Two done and a test fit.  Much better.

Match drilling the front brackets in place.

Will need a bit of trimming here and there to get a better fit...

Front brackets installed.

The bench is perfectly level, so I know the VP-X on the bench is level.  So, with this measurement I can check that the sub-panel is vertical.  This way I can make sure I'm matching drilling the rear brackets to hold the VP-X level.

And they're in!

Like!

On advice of counsel (in this case BobZ) I cut the upper mount holes to be slots.  This way, to remove these boxes I'll only need to loosen the top screws and not have to fully remove them.  Thanks Bob!

And it's done!!

Another view.  When the top front skin is riveted in place this whole structure will be very stiff and strong.

Another view.  All the boxes are screwed in place with M4 screws, lock washers and medium (blue) Loctite.

2.5 hrs. continued work on the sub-panel.

These should be plenty stiff and strong enough to hold the ADS-B/transponder.

Rivnut installed with Loctite 277.

Both done.

The mounting flange I fashioned.

And it's installed.  Very strong and stiff!  For me this was easier than trying to connect to the firewall since the firewall is covered with soundproofing.

Nice!

Now on to the mounting of the VP-X.  Using my sheet metal bending machine... ;-)

Two brackets for the front.

And let's make brackets for the back.

Bent to shape...

Front with real box in place.  The box will need to be spaced a bit below the sub-panel to make room for the rivet head which will be done from the bottom up to mount this bracket.

These need to be stronger vertically (they could bend), so I'll bend up the sides to make it strong in both dimensions.  To be continued...

1.5 hrs. on brackets...

On advice of counsel (Jean @ TAF CA) I removed the two sharp inside corners.

Rivnuts in.

Now to locate it on the sub-panel.

My mini airplane. ;-)

Starting to match drill...

What's under those holes...

Cleaned, deburred and riveted!

While it's pretty solidly in place I will add some diagonal straps from the back of the sides of the unit to the top of the sub-panel.

1 hr. last night starting to fabricate the brackets for the hanging boxes.

The shape of the brackets to hold the front of the ADS-B box.  I know I could make a simpler one that would connect to the bottom of the sub-panel flange, but since the box is fairly heavy I felt better with it being on top of the flange.

Ready to cut.

Cut and shaped...

And this is how it will attach.

With the box in place.  Need to drill the holes and insert rivnuts.

Both sides cut and shaped.

This side of the box has a cooling vent, so I need to consider that...

...So I cut that out of the bracket on that side.

I forgot to mention the other day that I successfully connected to my VP-X box.  I installed the configuration software on a different laptop and this time it worked:

SteinAir, of course, had configured it for my application.  Nice!

3 hrs. on the sub-panel.

Time to cut out the pieces for the bracket to hold the 20 and 245.  These were 9" x 9".

I left an inch on each end for the flanges.

I don't have a machine for bending sheet metal, so this will have to do...

Works pretty well!

This is how I applied even pressure to bend it.  Some hand bending too.

Nice!

To bend the second piece you need to make sure it will overlap properly, so you can't just do it by measurements.  Lined them up and figured out where to make the bend.

And it worked. :-)

Matched drilled and riveted!

Figuring out where to mount the boxes.

All rivnuts in!

Perfecto!  Took 2 hours to fabricate this bracket which is probably the most complicated thing I've had to fabricate in the whole build.

Time to put it on the sub-panel.

Matched drilled and riveted in place!

Just have to do the brackets for the boxes which hang underneath.  Like!