Jason McDowell: Why I Upgraded My Cessna 170B with Garmin Avionics

By Jason McDowell

A contributor for Flying Magazine and other publications, Jason McDowell is renowned in the aviation industry for his expertise in all things planes — especially his 1953 Cessna 170B. Nearly 130,000 accounts follow his Instagram page, @cessnateur.

I realized long ago that the part of my 1953 Cessna 170B most in need of improvement sits in the left seat. New to tailwheel flying when I bought it, our time together has been defined by the resurrection of rusty knowledge and by clumsy landings. Regarding flying skills, I work in mediocrity as other artists work in oils or clays.

So it was with a certain degree of shame that I began looking into a panel upgrade. As far as I could tell, my dated panel was not the element holding me back. For my fair-weather jaunts into tranquil grass strips nestled among the rolling hills of rural Wisconsin, it seemed to function just fine. How could a simple, VFR-only pilot like me benefit from a complete panel overhaul?

To be fair, my existing panel did resemble the conn of a 1940s-era submarine. It had an individual physical gauge for each engine parameter, and many of those gauges were scattered on the far end of the cabin, well outside my field of vision. An episode of Seinfeld could have started playing on the oil pressure gauge, and it would likely have been miles before I ever took notice.

Close Call Further Highlights Need for Upgrade

The original panel as shown in McDowell’s Cessna 170B cockpit was functional but dated — with key information scattered in random areas. Photo: Jim Stevenson

As it happened, my first lesson in the airplane highlighted this concern. As I was demonstrating slow flight, practicing some stalls and learning the airplane, I was fully focused on the actual flying. Fortunately, my instructor glanced at the cylinder head temperature (CHT) readout and questioned whether 550 degrees was a normal reading. Thinking back, it’s chilling to consider how long it would’ve taken me to notice it flying solo.

As far as I knew, 550 degrees was not a normal CHT, and I vaguely recalled reading that it was, in fact, 25 degrees beyond the uppermost limit on my engine. An immediate power reduction and quick descent took us into a nearby private grass strip, where we discovered I had left the cowl plug in place prior to takeoff. Fabricated from scratch by the previous owner, the cowl plug was completely invisible from inside the cockpit, and an interrupted preflight inspection provided the last link in a chain of unfortunate events.

Several months and a top overhaul later, I was back in the air and far more attentive to my engine’s health. I extended my scan to all parts of the panel and found myself wishing for more comprehensive engine information. I didn’t like only knowing the CHT of one cylinder, and I didn’t like the vague data that was presented to me by the other antiquated gauges.

Could this top overhaul have been avoided with a more effective presentation of critical engine information? Looking back, it’s very likely. Photo: Jason McDowell

When to Refuel? That Used to Be the Question.

I was also growing tired of calculating my fuel level by flight time and playing it safe by refueling well before it was necessary. It would be nice, I reflected, to know my fuel burn, and it would be especially helpful to have a more reliable indication of the fuel quantity on board. This is when the Garmin GI 275 Engine Indication System (EIS) caught my eye.

The GI 275 EIS appeared to compile all the data I wanted into an intuitive, easy-to-read display. Unlike my friend’s engine monitor from a competing manufacturer, it wasn’t necessary to hold one button while cycling through numbers on another. I discovered that the GI 275 had an interface that was easy to use. Best of all, more than one parameter is displayed at any given time. If you should inadvertently exceed one, it turns bright red, drawing immediate attention to the issue.

I dug further into my panel upgrade research with the ferocity of Ralphie checking the mailbox for his Little Orphan Annie secret decoder ring. Going down the list of functions provided by the GI 275 EIS, I referred to a photo of my panel and began placing an X over each physical gauge it would eliminate. Before long, half the panel was covered in Xs, and I had determined that a single GI 275 EIS could eliminate no fewer than nine individual gauges on my panel.

Not only would all that data be compiled into an intuitive display, but it would also bring that information into my immediate field of vision. Combined with the provided visual alerts, it would make it far more likely that I’d notice a concerning issue well before it evolved into a full-blown problem. That, I decided, would equate to some serious peace of mind.

A Clumsy Vacuum Pump

Nice as all these benefits would be, it wasn’t until I considered my vacuum system that I finally decided to seriously consider a panel overhaul. My 170 was originally manufactured with venturi tubes to power the gyro instruments. Sometime back in the 1960s or 1970s, a previous owner did away with the venturi tubes and installed an add-on, belt-driven vacuum pump. And it was the most hideous modification I’d ever seen.

The aftermarket vacuum pump was so massive that the modification required the installation of a larger nose bowl from a 172 just to house it. The pump’s pulley extended well forward of the cowl inlet, coming to within 5-10 millimeters of the aft edges of the propeller blades. It was ugly and cumbersome, and I cringed to imagine what would happen if the wrong component were to fail.

I realized that if I was going to install a GI 275 EIS, it would make sense to also eliminate the vacuum system, replacing my vacuum-driven attitude indicator and directional gyro with two more GI 275s. The installation would clean up my engine compartment, eliminate multiple potential mechanical failure points, reduce weight and increase reliability. It would also consolidate seven of my physical gauges into just two.

And so began my major panel overhaul. Could I live with the existing antiquated panel? Sure. But would a new panel instantly add a legitimate safety margin to my flying? It would indeed. With the decision made, I moved on to what would prove to be the most fun step in the process — designing a panel that blended modernized functionality with a vintage aesthetic.

A ’50s-era vintage panel retains a retro aesthetic while gaining modern functionality and safety.

One of the most interesting and enjoyable parts of the upgrade was the design phase. Rarely do aesthetics, human factors and technical constraints become so closely intertwined, and for an owner with a passing interest in any one of those aspects, the project becomes a series of creative exercises. In the overall process of upgrading the panel, this is where the real fun began.

As the owner of a 1953 Cessna 170B with its original paint, the aesthetics of the panel were a particularly fascinating concern. While my weathered exterior paint creates the look of a rat rod, the scheme is original, complete with vintage stripes and classy two-tone blue paint. Overall, I liked it and wanted to ensure the new panel retained the period look to the greatest extent possible.

It wasn’t until I took a close look at the panel itself that I noticed how many vintage design elements remained. The plastic trim surrounding the engine controls featured a cool retro pattern of light blue diamonds atop a dark blue background — pure 1950s style.

The yokes were an even nicer surprise. Like so many yokes in GA aircraft around the world, they had, at some point, been wrapped with cheap golf club grip wrap. For the life of me, I couldn’t figure out why. When I finally decided to snip the plastic ties and unwrap one of my yokes, my disdain was replaced by surprise and gratitude.

What I had always viewed as an unnecessary, cheesy addition to the yokes had, in fact, served as an effective means of preservation. Beneath the plastic wrap lurked a beautiful ivory finish with intact Cessna logos. I had no idea my yokes were so cool-looking.

The Importance of Maintaining a Vintage Look and Feel

Now, it was more important than ever to retain a vintage aesthetic. And in my case, this meant retaining as many round gauges and instruments as possible. Fortunately, the Garmin GI 275 flight and engine instruments pack a ton of technical capability into standard round cutouts. So I went with three of them — one to serve as the attitude indicator, one as the HSI and a third for engine monitoring duties.

I’d been carefully planning my panel layout in my head. This isn’t always straightforward, with many possible arrangements for both the gauges and the radio stack. To start, I determined a layout I did NOT want.

Browsing various social media pages and groups, I observed a popular trend. A fair number of owners appeared to be wiping their new panels clean, leaving them devoid of all but the most necessary displays. Often, the result was a panel that was empty save for two or three small screens on the pilot’s side. It was an aesthetic that made perfect sense for a competition short take-off and landing (STOL) aircraft or a modern, fast homebuilt. But for a classic 1950s Cessna, I wanted a cohesive look.

Designing a Panel That Fits My Needs

I dusted off my meager Photoshop skills and got to work creating a layout that resembled some of Cessna’s early panels. Using a combination of new Garmin displays and legacy analog gauges, I arranged them in a continuous arc across the top of the panel. This resulted in a balanced look that utilized most of the panel width, including the most critical information positioned in front of the left seat.

I initially wanted to place the radio stack in the center of the panel, just below the arc. This made it easy to see and use from either front seat. However, technical constraints threw a wrench into the plan.

Like many Cessna models, the 170 has a large Y-shaped yoke connecting the two control yokes deep within the panel. The Y-yoke requires open space to move fore and aft, allowing the control yokes to command the aft movement of the elevator. Any radios or instruments more than a few inches in depth will restrict the aft movement of the yoke, effectively limiting nose-up elevator travel. This would be unacceptable, and it meant that I’d have to find an alternative location for my radio stack.

The large, black “T-yoke” behind the panel links the two control yokes. More critically, it requires open space to enable free forward and aft movement. This limits the depth of gauges in the central portion of the panel. Photo: Jessica Voruda

This also meant that I’d have to keep my tidy arc of instruments positioned as high on the panel as possible. Fortunately, the GI 275s are just thin enough in height to enable this. If an owner wished to position modern flight instruments any lower, they could opt for the Garmin G5, a rectangular display that’s only a few inches in depth. I like how Garmin offers this kind of flexibility within its ecosystem.

With the flight instruments and engine monitor arranged, I moved on to the radio stack. Keeping the GNX™ 375 GPS navigator and transponder as high as possible to make the display easier to see, I grouped the radios and audio panel together in the existing radio stack location near my left knee. I was initially a bit concerned that this would be too low to easily read the digital displays, but fortunately, the Garmin display is easily readable even at extreme angles. The entire stack has proven to be easy to use as well, because it’s located exactly where my left hand falls, just beneath the yoke.

The Final Countdown — A Fun Challenge

The finishing touches were some of the most fun items to address. I wanted a reliable power source for handheld devices, so I installed a Garmin GSB™ 15 USB port on each side of the panel — one for the pilot and another for the passenger. I like these a lot because each has two power ports for excess capacity. For the passenger side, I opted for a dual plug that offers both USB-C® and an older USB-A to accommodate devices with older power cords.

Because I liked the retro blue pattern surrounding the throttle controls so much, I had Superior Aircraft Components scan and print it directly onto the lower section of the panel. I thought this was a nice solution, as typically, people only refresh the original section. Now, the cool vintage print adds a strong accent to the cockpit.

Finally, I freshened up the circuit breakers, toggle switches and push-pull knobs. The latter was especially nice, because my plane still had the original plunger-style mixture control that was nearly impossible to adjust with any degree of precision. Now, with the McFarlane vernier controls, fine-tuning is quick and easy, and the small changes are immediately reflected on the GI 275 EIS just above.

In the end, my panel was a significant investment. But in exchange, I received more than a fresh panel that massively improves the flying experience. I also received peace of mind that my panel and controls are safe and reliable. And I received a relatively future-proof panel with solid-state electronics that will serve me well for decades.

The constant arc of gauges is reminiscent of original Cessna panel layouts of the 1940s and 1950s, and the GI 275 family of instruments enables an elegant blending of classic style and modern functionality. Photo: Jessica Voruda

Perhaps best of all, I was able to blend modern functionality with a vintage aesthetic. While large, rectangular displays look slick in modern aircraft like the Cirrus SR22, they would completely alter the original look of a 1950s-era panel in a vintage aircraft. With the form factor and flexibility of the Garmin GI 275s, I kept my 170 looking like the vintage classic that it is while injecting it with technology like ADS-B, modern GPS navigation and advanced engine monitoring.

Want to modernize your aircraft and reap the benefits for years to come? Follow this link to get more info and find a dealer near you.