This month’s panel for planning comes from Boston area-based reader Bill Stevenson, who designed the new panel layout for his P35 Bonanza himself after thinking through the workflow he learned flying behind the Garmin G1000 panel in a Citation Mustang. He also scoped out every photo he could find of other glass panel retrofits in Bonanzas.
Like most all Bonanzas, this is definitely an IFR machine, and Stevenson’s missions are generally limited to the Northeast, although he occasionally flies to Florida.
“I almost always file IFR even for short flights in good weather because of the traffic density around the Boston area. I don’t typically plan to fly to IFR minimums, but am quite comfortable flying solid IFR,” he told me.
out with the old
When Stevenson got involved with the airplane it sported a center stack filled with King Silver Crown digital avionics including a KMA24 audio panel, dual KX155 navcomm radios, a KR87 ADF system, KN62 DME, KT76A transponder and mechanical flight instruments. There was also a Strikefinder lightning detection system and an JPI EDM700 engine monitor. While the aircraft had a clean instrument panel and logical layout, it was far from the glass automation he was accustomed to in the Citation. That was one reason he chose a Garmin retrofit suite of avionics. Another possibility is Dynon’s HDX Certified avionics, which are just as capable, but far different than the Garmin operating logic.
Because this was a complete refurb project, there were more accessories and systems to replace than just the avionics and now is the time to accomplish these tasks. Newer-style Beechcraft control yokes were sent out to be covered in the same leather that was used to refurbish the interior sidewalls. As a nice luxurious touch, cherry veneer inserts that Stevenson purchased for a furniture project were installed in the center of the yokes.
Other accessories included colored knobs for the engine controls, pilot and copilot frameless window vents, ventilation fans, new circuit breakers, Rosen sun visors and G&D thermal window inserts. These are a second set of 1/8-inch-thick side windows installed on the inside of the aircraft. They’re proven to reduce heat, glare and UV radiation.
“I remembered how uncomfortable it was in the A36 I owned previously when the door was closed prior to engine start. So I added ventilation fans that provide some airflow that can be directed toward my face. It’s not as good as air conditioning, but it really helps a lot,” Stevenson said.
Upgrades during the upgrade
Because this was a major project that took over a year to complete, Stevenson was faced with upgrading stuff he already bought. At the time, he planned on installing Garmin’s GTN 750 and GTN 650 navigators but halfway through the project, Garmin released the next-gen GTN TXi units. These are a major upgrade from the originals so Garmin’s regional sales manager, Michael Kerrigan, stepped up and offered an upgrade to the new TXi for a relatively small upcharge.
But another issue was more substantial. At the time, Garmin didn’t have an STC for the installation of its GFC 500 autopilot in the P35 Bonanza, so Stevenson’s only real modern option was the Genesys S-TEC 3100. This digital system wasn’t a bad alternative and Stevenson boosted the ergos. “I added the Garmin GCU 485 dedicated PFD controller to allow course, altitude and vertical speed to be easily set with dedicated controls, much like the integrated GFC 700 autopilot I had on the Citation Mustang,” he said. At this point, the GFC autopilot is approved for the aircraft.
The plane also has a 10-inch Garmin G500 TXi PFD, a 7-inch EIS engine display, a GTX 345R ADS-B transponder, a GTS 800 active traffic system, a GDL 69 SXM receiver, a Garmin G5 backup flight instrument, a Guardian CO detector, an Artex ELT 345 and a Mid- Continent Instruments and Avionics USB panel port with clock.
Partnering with a good avionics shop
Much of the avionics retrofit work was done at Infinity Aviation Group (www.infinityfbo.com) at Nashua, New Hampshire. It’s equipped to do maintenance, avionics, parts supply and line services. While the aircraft was on the Nagle Aircraft’s hangar floor at Stevenson’s home field in Bedford, Massachusetts, for the other stages of the refurbishment, Infinity’s Jeff Wall went above and beyond—driving down to work on the plane while other mechanical work was being accomplished. This allowed the avionics and airframe to be worked on in parallel rather than sequentially—a huge benefit that isn’t always possible.
“Steve Gosby of Nagle Aircraft did some of the work that would normally be done in the avionics shop, including installing sensors for the Garmin EIS engine instrument system and some of the switch and circuit breaker work. Both Jeff and Steve were great to work with and I was able to visit the hangar at least weekly to discuss progress and make some of the small decisions that pop up along the way,” Stevenson said.
Airsync data logging
One other system is the AirSync. It automatically uploads all the flight and engine parameters recorded by the Garmin suite over a cellular bridge when the aircraft is shut down. “I then have them forward the data to Mike Busch’s Savvy Aviation for engine monitoring, and CloudAhoy for reviewing each flight. It is a fantastic engine monitoring and flight safety tool, as I can see my airspeeds at each phase of flight, runway use, etc.,” he told me. We’ll look at the AirSync in a dedicated article.
Touchscreen transition
“My first flight was in the spring of 2020—when many people were hibernating because of the pandemic. The Garmin touchscreen does take some getting used to, but the logic is very similar to the G1000, so it was a relatively easy transition. My biggest issue was learning to brace my hand on the panel in turbulence—a couple of times I inadvertently switched frequencies, which is not a good way to make friends with ATC,” Stevenson said.
Got a panel for planning? Drop us a line and we’ll help noodle it.
