Chapter 22 – Backup Attitude Indicator

Just an update on the continuing project planning & component acquisition efforts.  I have been spending a lot of time both on my electrical system & subsequently on my instrument panel.  As I get more research under my belt, gain a bit more knowledge, and figure things out, I then of course ask my building buddies what their plans are for whatever I’m currently carrying on about.

In one of the latter iterations of my planned instrument panel, my buddy Marco noted the myriad of redundant capabilities I had for simply displaying airspeed and altitude.  Of course I want SOME redundancy in my systems for backup purposes, but having 4-5 different ways to measure airspeed may be a bit overkill!  I hadn’t intentionally planned on having this many, just so many of the newer avionics these days have built in extras that may add more than we need if we go back and assess our actual requirements.

One of my primary culprits in this area was the TruTrak Gemini PFD.  It’s a great piece of technology and really has a lot packed into a nice, small package.  But when I went back and re-assessed my requirements, I had included it on my panel for one primary reason: as a backup attitude indicator.  I had accepted the fact that it provides airspeed and altitude information simply as a bonus.  But at what cost?  Cost here meaning actual money, since at 5.4 ounces it wasn’t necessarily breaking any feasible weight allowance thresholds.

So, in the vein of saving money and sticking to a prioritized plan to get this project in the air soonest, I decided to forgo the extra ASI & ALT features built into the Gemini PFD and focus on the primary capability I needed here, again, simply a solid backup attitude indicator.  In my ensuing research I found a TruTrak ADI for sale on Ebay for way below half the cost of a new Germini PFD (and well below the new touchscreen 3-1/8″ TruTrak ADI as well).  After a number of emails back and forth with the seller–who had just pulled it out of an RV-8 during a panel upgrade–I decided to pull the trigger.

Now, I will suffer about an 8 ounce weight penalty vs using the Gemini PFD/ADI, but for now I’ll simply put the Gemini PFD/ADI (or whatever future equivalent) in the “planned upgrades” category, to be purchased down the road after my bird is flying.  Swapping TruTrak for TruTrak will be a fairly easy upgrade both physically & electrically, but will of course require a new weight and balance . . . but most likely I’ll have a few more upgrades & modifications in the mix around that same timeframe, so I’m sure a new W&B will be in order regardless.

Thus, introducing the latest addition to the instrument panel:

Chap 22 - Trutrak ADI

TruTrak ADI (3-1/8″) Features:
– Gyro / VS pitch display
– Bank Angle display
– Built-in Ground Track DG (via built-in GPS)
– High Bank Angle Warning
– Low Airspeed Warning
– Slip/Skid ball


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