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Thursday, March 01, 2018

Ch 22 - Electrical/Avionics - Part 11

Random thoughts on my GRT Mini/Garmin GNS-480 installation

The 2017 Rough River Canard fly-in trip I took with Wade proved a great success for the new avionics package. 

Ah, Fernando... long story.

I have since flown a lot of instrument approaches (in VMC) to test the installation, and while I have been vastly impressed by the new panel in so many ways, I have run into a few small issues, the bulk of which have already been fixed with a few software updates.

Initial roll servo testing

I was a little reluctant at the time to blog about these “teething" issues because they are to be expected with cutting edge equipment, and the last thing I’d want is to cause people to steer away from this incredibly good product. 

Here’s my take on a couple of things one should keep in mind…

First, usually the GRT Mini is installed as a standalone unit in VFR planes (though it is IFR capable), or as a backup to a bigger screen in an IFR installation. Because I am probably the only one out there running two Minis in IFR as primary EFIS, one would expect this configuration to not have being extensively tested yet (or at all) by the factory, so some of the issues I’ve encountered might have never appeared in any other installation, and are probably unique to my setup. Case in point, a random roll trim command indication that turned out to be caused by a lack of coordination between the units as to which one was primary and which one was secondary at the time. That software bug has been squished with an update.

Going missed approach

Second, the Mini runs a version of the same unbelievable software that GRT’s bigger units run but only has half as many buttons and knobs. That means that the pilot has access to truly incredible features but at the cost of more button pushes and knob twists. This requires him to quickly become a fast and accurate “typist”, as any one mistake will require him to go back through at least three layers of menus to get back to the same point, and fix the error. Screwing up one’s setup during an approach by clicking first and thinking next is not fun (ask how I know that), and care must be exercised in order to avoid that at all cost.

I found that writing down the steps to follow for different kinds of approaches, and forcing myself to refrain from randomly pushing buttons, is essential, at least until I have a lot more practice under my belt.

VNAV LPV approach to 200' decision height

Third, at least half of the complexity in my panel was introduced by the incredibly capable GNS480, of which I cannot sing its praises enough. The point here is that when one stacks layers of complexities over each other in order to do "incredible things", one has to become and remain proficient with both the Mini and the GNS, and be “clinical” in his approach to IFR flying to get the best out of this powerful package.

Parallel entry into the holding pattern on autopilot

To date, I have only installed the roll servo which will be the subject of another post, while the pitch servo is still on the bench waiting for me to find a suitable location to mount it. This will probably require me to rip out the grounding bus and the ARINC module to make space, then find another place for them. There will be some glassing involved, so warm weather would be a plus. I’m thinking about pulling the trigger on the installation in the early spring, meanwhile I am flying on the one axis as much as possible, keeping the variables at a minimum while I practice and test.

I have two gripes left as of now, but they are fairly minor. The main one is the premature shallowing of the bank angle as the plane approaches the commanded heading. This might be ok flying VFR, but it would be an issue in IFR. GRT knows about it and I'm awaiting the software fix. The other is that the autopilot disconnects when I switch it from AP1 (top EFIS) to AP2 (bottom EFIS). It seems to work only if I also switch the bottom EFIS to PFD mode. I haven't gotten an answer to that question yet, and I’ll be going flying soon to run a few more tests.

To sum it up, while I still have a couple of small issues that are being worked out to everybody’s benefit, I LOVE my instrument panel and cannot wait for the pitch servo to go in. Were I to do it again with more panel room at my disposal, I’d install a Mini and an HXr (big screen), but in the same situation I wouldn’t hesitate in the least to install two Minis as I have.

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