Reader Correspondence: May 2020


How come you guys left out the Lycoming IO-390 STC performance mod in the March 2020 Aviation Consumer Used Aircraft Guide for the Cessna Cardinal 177RG? Please publish as us aviation performance nerds would like to know what that engine does for climb and cruise performance in this airplane. Love the magazine and all that you report in sister publication

Brian Burton – via email

We’re not sure how we missed that. It’s been a while since we’ve flown one, but in general you can expect shorter takeoff runs, an extra 130-FPM climb rate and a couple of extra knots in cruise from the 210-HP four-cylinder Lycoming IO-390-A1A6.

The beauty of the mod is that it’s pretty much a plug-and-play upgrade, meaning you can use the engine mounts, exhaust, fuel lines and even the original propeller left over from the removed 200-HP IO-360. It even fits under the old cowling, although cooling issues left 1971 and 1972 model-year RGs out of the STC. You will need some other hardware, including an oil cooler and lines, which add to the cost and the installation effort.

As for pricing, this could easily be a $50,000 mod for a new IO-390, which includes a Unison Slick Start ignition booster. But an IO-390-equipped 177RG should fetch more money at resale, plus the engine has been reliable.


I took the big plunge and am currently having a Garmin G3X Touch integrated avionics suite installed in my Cessna TR182, saying goodbye to my old King KCS-55A HSI. 

Part of my upgrade decision was that I already had a Garmin GNS 430W navigator and a Garmin-AT SL 30 navcomm in the plane, and understood (according to Garmin sales material) that they would both play with the G3X Touch. I also have an S-TEC 55X autopilot.

Apparently, somewhere along the road there has been a software change and with a third-party autopilot the G3X Touch  will no longer support both the GNS 430W and the SL 30 nav. It supports the SL 30 comm, but not the nav. Purportedly, somewhere down the road a software revision will be released to correct this. Deep in a revision of the installation manual it states this new non-compatibility.  My avionics shop told me they found this out the hard way after previous installations had compatibility issues. My shop is wiring up the SL 30 nav to the G3X Touch in anticipation that this will eventually get corrected.

Still, I found this out mid-installation and don’t have a good taste about the whole thing. I love Aviation Consumer and it’s been a major influence on quite a few of my purchases. Keep up the good work.

WD Lewis – San Carlos, California

We asked Garmin about this and were told the G3X Touch does not support nav source selection for non-Garmin autopilots. Therefore, when a non-Garmin autopilot is interfaced to the G3X system, only one external navigator (GPS and/or VHF) can be connected to the G3X Touch. A second external navigator, if installed, must retain its own dedicated CDI display. 

The main reason for the limitation is that the FAA won’t allow a scenario where the autopilot is flying from a nav source that is different from what is being displayed on the G3X PFD (in other words, the autopilot is flying something different from what you’re looking at on the display). 


Thank you to Larry Anglisano for sticking up for purchasing used homebuilts—and for promoting local EAA chapters—in his First Word column in the April 2020 issue of Aviation Consumer. I’ve built my own and purchased existing completed kits and he’s right that you need a good eye when buying something someone else built. 

He’s also correct that a Van’s Aircraft RV-6A can make for a good used homebuilt because there are a ton of them in the field. But he botched the model line, or at least got the models reversed. The RV-6A is the one with the tricycle landing gear, not the straight RV-6. Thanks for your good work.

Herman Fishmann – via email  


Larry Anglisano
Editor in Chief Larry Anglisano has been a staple at Aviation Consumer since 1995. An active land, sea and glider pilot, Larry has over 30 years’ experience as an avionics repairman and flight test pilot. He’s the editorial director overseeing sister publications Aviation Safety magazine, IFR magazine and is a regular contributor to KITPLANES magazine with his Avionics Bootcamp column.