Modifying Older Aircraft


By Nathan Hernandez

So you find your aircraft. You’ve wanted one, looked for one, and finally found one. It’s a great aircraft and was a great deal but the avionics are old and maybe outdated. Where do you start?

421c-beforeMost people start looking at before and after pictures on various websites and get some ideas. Then they get a quote for that full glass panel upgrade they saw online and….once their heart starts beating again and the sticker shock sinks in you ask the real question – what do I really need?

First of all, please remember this is about avionics. If your engines are past TBO, then get that done ASAP!

Avionics can perhaps be broken down into 3 sections- radios, flight instruments, and your autopilot. I tell people that electronic flight instruments and a great autopilot are wonderful tools but they are not practical without a good foundation. Your foundation tends to be the radios. That is, your audio panel, GPS, NAV, COMM and transponder. Those are the foundation of a good avionics package.

Start with your audio panel and transponders when you shop. You can have the biggest and best GPS/NAV/COMM on the market but if you cannot communicate with tower due to a failed audio panel or report altitude due to a failed transponder, well, then you’re grounded. That big awesome display means nothing at that point. Make sure your installers are putting in all new wiring and jacks for your intercom. The transponder needs a good serial encoder. This will reduce the risk of failures later and good shops will require it. No one wants to spend good money on their aircraft and have issues because they saved421c-after a few bucks with old wiring or an old encoder.

After those important details, at this point, you can look at the new displays with the GPS/NAV/COMM all built in. Personally, I recommend you aim for one really good unit and a strong secondary. Most of us are not going to buy an aircraft and spend the aircraft’s value on new avionics. Installing 2 large GPS/NAV/COMMs is great and looks cool but one with a solid back up will save you money and keep money in your pocket for the EFIS, autopilot, or maybe something like fuel? Just a thought.  Great avionics manufacturers like Garmin, Aspen, Sandel, Universal, Rockwell Collins, etc. have done their homework and produced systems with not only great features but great reliability and quality.

Don’t let yourself get caught off guard when you look to modify your aircraft. It’s always fun to go big and your avionics shop will be happy to help you do that. Make sure the shop you go to is looking out for your best interest. I have had clients ask me to install a nice EFIS with old unsupported radios. That does not help when you’re on final approach and your audio is not clear enough for ATC to give you clearance. What’s behind your panel or not in directly in your field of vision can be as critical as that nice looking big display in front of you.

For questions, comments, or even just to chat about anything avionics related, feel free to give me a ring or shoot me an email whenever you want.

Nathan Hernandez (321)255-9877 ext.291


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