13.2 Instrument Panel Layout

This entry is part 33 of 67 in the series 13 - Electrical / Instruments

One of the huge pitfalls that can ensnare a builder is what I call “panelitis”.  That’s when you start building the airplane and at the same time you begin designing and purchasing the components for the panel.

The problem with purchasing your radios and GPS, audio panel, instrumentation, etc., is that 1) the warranty will expire WAY before you get close actually putting it in the airplane and 2) technology will make the stuff you’re already bought obsolete.

Which is why I avoided anything to do with equipment purchases for the panel.

A few years ago I bought the EIS (Engine Information System) because I was installing the engine.  Then 8 months ago, I bought the Vertical Power VPX-Pro power distribution system because it was time to actually start pulling wires. So you see, I’ve been doing good. 🙂

From the beginning, I was planning on a “glass panel”. This is where the traditional “six pack” of gauges are replaced by an electronic display.  Just about every aircraft made today has this type of display.

Cessna-172-Instrument-Panel  vs.  c-172-g-1000-glass-cockpit

The vendor I was going to use is Grand Rapids Technologies. They’ve been making EFIS’s (Electronic Flight Information Systems) for a while and they have an excellent reputation. At the time, they had a couple different sizes of displays and I made a couple different layouts.


This is what I would call “rev 1”. The vertical dashed line indicates the center of sight from the pilot’s seat. Here I’m using two screens (one for flight information and one for engine data), a traditional radio stack, a circuit breaker panel and a trio of old school gauges as backup.


This layout is similar to rev 1 but uses slightly larger screens in a side by side configuration. Another builder, Terry Miles, told me that reaching across with your left hand to work your primary radio can be really annoying. He suggested positioning it for easy left hand access.

I had actually purchased the backup instruments from my good friend Albert about 4 years ago. But then… technology advances. Companies started coming out with miniature EFIS that had built in batteries. This would eliminate the three gauges. So I sold the backup gauges (and even made a couple dollars). Over time, the backup EFIS units have gotten smaller and cheaper.



This is rev 3. Just like rev 2 except the backup gauges are replaced with the small, backup EFIS.

Then about a year and a half ago, I heard that GRT was coming out with some really new equipment. You’ll notice that all the designs that I’ve done have two screens. That’s because one of them is for flight information and the other is for engine information. I’ve always felt this is kind of wasteful. Well the new EFIS allows you to use an Android tablet as the second display. And… here’s the best part:  remote avionics. Which means that the radios, GPS, transponder and audio panel will no longer be taking up panel space. They will be mounted behind the panel and controlled from the EFIS.

So I made another panel layout.


The new HXr screen is much bigger and I eliminated the circuit breaker panel because the VPX is controlled by the EFIS (or the tablet). This makes for a much “cleaner” looking panel. As soon as heard about the new EFIS, I got a quote. Huge savings over what I was planning. Then every time I stopped by at Sun-n-Fun or Oshkosh, I would have the quote updated.

Oh yeah, they also came out with their own autopilot. Which was a fraction of the cost of the S-Tec 55x that I had bought which was going to be a freakin’ nightmare to install.

See how waiting is a good idea?

So about 6 months ago I ordered the EFIS and auto pilot servos. I didn’t really need the EFIS yet, but it’s the only way to see what’s happening with the VPX power system.

So now it’s present time.

I’ve been trying to decide on whether or not to wire everything myself or use the Approach FastStack Hub. Normally, some of the wires from one device may go one, two, three, or more other pieces of equipment. So you have 25 wires coming out of one box with 10 going to box A, 5 going to box B, and 15 going to box C. With the FastStack Hub, everything connects to the hub. And the hub takes care to sending what to where. I asked around and everyone that’s done it both ways all said that would use the hub in the future.

I called Tim at Approach FastStack, told him what I was doing and he got to work.  A day later, I got “the call”.

So here’s the deal: All the radios, GPS, transponder, autopilot… EVERYTHING communicates with the EFIS. I’ve got about 11 devices in total that talk to the EFIS using serial ports. And the EFIS has eight serial ports. Don’t ask me how, over the last 18 months, I’ve gotten multiple quotes from GRT for a configuration that simply won’t work.

I called GRT and they confirmed what Tim had discovered. The only way to “fix) this is by adding another EFIS screen (8 more serial ports). The guys at GRT felt pretty bad that nobody ever noticed this so they gave me a pretty decent discount on the second screen. It still stings. And I’m going to lose some of the panel space that I would have been able to play with… and for a screen that I really don’t need… I just need the serial ports that come with it.

But at the end of the day, I’m still better off than I was 2 or 3 years ago.  (yeah, I’m trying to be positive)

Back to the drawing board for a new layout.

Electrical System - New



Series Navigation<< 13.6.3 Ground Power Receptacle13.3.5 Avionics Wiring >>