May 2009 Issue
Roll Your Own Glass: No Ideal Solution
The aftermarket is rich with retrofit displays for the radio stack and instrument panel. But even after investing a bundle, most solutions still come up short.
As we pointed out in our April issue of Aviation Consumer, there are some sweet deals on used, glass-cockpit aircraft. But for many owners, this jump in the ownership food chain might not be practical or affordable. If you’re perfectly happy with your current wings (or just have good reason not to sell right now) but lust for the big-screen glass that dazzle front and center in new cockpits, you have options. Unfortunately, there are caveats a-plenty. Our definition of glass here includes a primary flight display (PFD) and some kind of modern multi-function display (MFD) and modern IFR-GPS the likes of Garmin’s GNS-series navigators. Traffic and satellite weather are in the mix as well. We’re talking fully certified systems focused toward certificated aircraft—nothing experimental or portable installed on the panel. Step one is a review of your stock electrical system. New, all-electric aircraft require electrical-bus and electrical-system redundancy. Your old airframe likely doesn’t have dual batteries, dual alternators or dual electrical busses, and equipping a 70s-vintage Skylane to these specs just isn’t going to happen. Some equipment won’t accept a 14-volt input voltage, including the popular Avidyne EX500 MFD. That means a current-hungry voltage converter if installed in a 14-volt system. That brings us to the other major issue: overwhelming the electrical system of an older bird in supporting all those fancy new avionics. Many 14-volt alternators weren’t intended to keep up with this intense charging demand. Some owners with full panels report increased incidents of alternator failure or screen blackouts when running high-draw accessories like landing lights or gear and flap motors. Have your shop do an electrical load analysis for your proposed avionics suite. And always keep a healthy battery in the aircraft. It works hard. Reworking the original bus and installing properly rated push/pull circuit breakers and proper labeling can be surprisingly pricey and time-consuming. Is it worth it to rewire analog engine gauges and warning lights while the panel is open? How about replacing old switches with modern, lighted rockers? What about all that old wiring lurking behind the panel and woven through the airframe? This can get expensive even before putting in the new stuff.
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