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  Dr. Rogers Bonanza Panel Evolution & Eaton Annunciator Implementation



Below is a narrative by Dr. Dave Rogers outlining the history of his Bonanza panel evolution from 1990 including the implementation of Eaton Annunciators into his panel:


 Let's label the below four images

1. Full Panel;

2. Floating Panel;

3. Upper Panel & Annunciators;

4. Intermediate Upgrade.






What you see in the Full Panel image is the final configuration before I sold the aircraft.


When I bought the aircraft in 1990 it came with a standard six-pack, and HSI, which was relocated and is now shown on the Full Panel image behind the pilot's yoke. A Century II autopilot and a PSS 60 altitude hold is shown at the bottom of the center panel. The radio stack contained an audio panel, two Mark 12Ds, ADF (low row left on the floating panel, a transponder and a Foster loran.


On the right canted panel was an Alcor EGT and a fuel flow computer. Quite a well equipped aircraft when purchased. I was the third owner.


In the early 1990s I added the Stormscope (1992), the Sandel and a PS1000 (1991) intercom. With the addition of the Sandel the existing HSI was moved to the lower panel below the floating panel. I also added a CHT gauge to the cant panel.


Because the Sandel CRT stroke display depended on a bulb, switching was also designed and installed to allow the Century II to drive either the Sandel or the NSD360 HSI for redundancy in case the Sandel bulb blew. It never happened but...


And then came GPS.


In May of 2002 one of the radios was removed and a Garmin GNS-430 installed and was later upgraded to WAAS in Nov 2007. With the GNS-430 WAAS upgrade the EATON annunciators were installed. Total cost of the annunciators as installed was just under $2k.


For redundancy the system was upgraded with an Eaton annunciator illuminated switch. The switch allowed either the Sandel, as HSI-1, or the non-slaved NSD-360 driven by the Mark 12D or the Foster LRN-500 (Loran) were selectable as HSI-2 to drive the Century II autopilot. This switch is shown in the Upper Panel & Annunciators image as AP Select. Look carefully and you can see the HSI1 and HSI2 illuminated legends.


In about 2007 the FAA required that various annunciator indications be within a specific distance of the GPS in line of site of the pilot. There were a number of outfits that were providing `boxes' for a bit North of $2k+ for just the required indications. I did not like the looks of them nor the design. Todd Adams of Lancaster Avionics at Lancaster Airport in PA suggested the EATON annunciators.


I also did not like the fact that various older `annunciator' lights were scattered all over the panel.


In November 2007 the Loran was replaced with a GNS 400W/500W WAAS again for redundancy. The ability to switch between HSI-1 (GNS-430W) and HSI-2 (GNS 400W/Mark12D) was retained. Four additional Eaton annunciators, two for each GNS, were installed to provide display of MSG, WPT, APR, INT, VLOC, GPS, OBS, TERM. These are labeled GPS 1 and GPS 2 in the Upper Panel & Annunciators and Intermediate Upgrade images. Four legends are displayed in each annunciator. You can see GPS displays best in the Intermediate Upgrade image.


At the same time, various other indicators, as shown in the right hand row of four annunciators, were added. A remote GEAR UP/GEAR DN indicator is shown at the left.


A GYRO/ALT OUT warning is next. Both of these are push to test. The third is an OIL P/CHT warning. The last one is a dummy installed as a `Spare'. It's really just the head.


The Eaton annunciators are best acquired customized. As mentioned above, they can have up to four legends when used as simple indicators. They are also available as toggle switches, with or without push to test.


The Eaton annunciators are best acquired through a distributor. Let the distributor know what you want and let them deal with Eaton. A suggested distributor is


Phil Gamboa

Associated Aircraft Supply

3250 Stone Myers Pkwy, Grapevine, TX 76051

1-800-369 3212, 214-331-4381


You can also contact

Todd Adams

Lancaster Avionics



He also adds:

"I see no real downside to vacuum/pressure driven analog gauges provided you have a decent backup pump. Installed, the backup pump is about the cost of a G5 installed.

Electronics quits the same as anything else."


David F. Rogers, PhD, ATP

Professor of Aerospace Engineering (Emeritus)

Annapolis, MD


"Pilots know how TO fly airplanes.

Aeronautical Engineers know HOW airplanes fly.

Seldom do the twain meet."



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