Trim Wiring Vindication & Avionics Learning Curve

Being a nasty snowy day, decided to stay home and work on the April 15th deadline, but first want to mention a few items discovered after powering up the DOG Aviation’s RV12 avionics for the first time.


One of the first things completed after the initial powering of the avionics was to install the SkyView version 13 software from the Van’s site along with a few configuration files Van’s supplies with preset configurations for the RV-12. The software can also be downloaded directly from the Dynon site, but it will contain no presets unique to the RV-12 forcing the user to run through all the menu settings manually.


The configuration menu shows the system items on the SkyView’s buss, but there are a few items that do not show up because they are connected separately to the serial ports such as the transponder, GPS250 or 2020, ADS-B, and the Garmin GTR 200 Radio, ect.  Interestingly, I only saw an entry for the GPS250 (which I assume came from the Van’s configuration files) but do not see the GPS2020 that is installed … it was also NOT in the list of possible devices.


Thinking the red X for the GPS may be appearing because the airplane was inside, yesterday afternoon between snow storms the fuselage was rolled outside of the hangar and the avionics powered up … after waiting quite a while, the red X for the GPS did not go away. By doing a little more reading, it appears that the new GPS 2020 antenna is ONLY supported beginning with SkyView version 14 … so that is likely the main issue since the system does not see the GPS 2020 antenna.


Dynon released version 14 earlier this year but there were some unsavory issues created with older SkyView screens, so Dynon temporarily suspended version 14 to make the necessary corrections to the software. Recently, Dynon began distributing SkyView version 14 again. I could download version 14 now directly from Dynon … but will opt to wait for Van’s to post version 14 with configuration files unique to the RV-12. I have plenty to do in the meantime with fitting the cowling and finishing off the engine compartment … so can afford to wait for a little while in the hopes Van’s posts their preconfigured version of Dynon’s SkyView 14 on their website soon.


Yesterday, I also performed the Garmin radio software update to the latest version 2.7 … it is easy to do. Starting with the radio powered off, just place a micro SD card with the latest software file on it into the micro SD slot on the front of the radio … then power up the radio. The radio will identify the software version on the micro SD card and compare it to the version in the radio … and if the SD card is newer, it will ask to upgrade the radio … select yes and a minute or so later it is done.


Frequent readers know I plan to use a couple of switches on the Tosten CS-8 control grips to control the Garmin GTR 200 radio. One switch will be used for swapping between the active and standby frequencies. The second switch will cycle through a user saved table of up to 20 stored frequencies. I ran into a little problem here. I remembered there are quite a few configuration menus but could not get into them at first. The pilot’s guide that comes with the radio DOES NOT show the user how to get into the configuration menus. For the most part, it only shows how to get into the audio settings by pressing the menu button which brings up a settings menu that allows the user to change various audio options. My radio did not come with an instillation manual, so needed to download one to my phone while at the hangar to discover the “mystery” of how to get into the GTR 200 radio’s configuration pages. For those builders interested … the procedure to enter the configuration menus is: With the GTR 200 radio powered off, press the center button on the right knob and keep it depressed … then power up the radio. After a few seconds the radio will allow access to a grouping of configuration menus. There is a discrete configuration menu there which is where the two discrete inputs can be configured. I configured Discrete Input 1 to swap between the primary and standby frequencies. Discrete Input 2was optioned to cycle through the user stored frequencies.


Of course, I couldn’t wait to see if the wiring change I made for the trim motor was correct … so I was eager to try the trim switch mounted on the panel. Vindication!!! The trim motor worked precisely as I predicted it would back on March 5, 2016 in this post:


http://www.dogaviation.com/2016/03/wiring-discrepancy-identified-in-trim.html


When pressing the panel mounted trim switch calling for nose down trim, the anti-servo trim tab on the stabilator moved up … just as it should. I also checked the trim switches on the control stick to make sure the trim tab moved in the appropriate direction and it does for those as well! So there is definitely an error in Van’s plans on page 31B-04 step 2. I can’t speak for all RV-12’s, but those builders building with the intent of installing the SkyView Autopilot & Knobs Panel modules during construction phase will do themselves a favor if they place the wire identified as  +Tab Up on pin 32 of the fuselage connector and NOT pin 31 as shown in figure 1 in section31B-04. Doing it now will save you from going into the connector later and extracting the wires and rolling pins 31 & 32.


The built in run-away trim protection built into the AP panel module also worked as advertised … it will allow the trim motor to run four or five seconds then stop. Releasing the trim switch momentarily will reset the trim circuit and the trim motor will move again when the switch is activated again. A nice safety feature in case a trim wire becomes shorted to ground.

Electrical & Avionics Initial Power On Testing

Yesterday, was another momentous milestone at DOG Aviation … the electrical system was powered up for the first time followed shortly thereafter by the avionics. Happy to report there was no smoke or blown fuses and all the electrical components and Dynon Skyview Modules appear to be playing nicely together. More on that later.


Prior to powering up the system a few tiny tasks were completed beginning with completing the instillation of the static and pitot lines to the backup instruments. Once a final routing for the lines was established the fittings for the poly lines were screwed into the instruments. The lines can be run in no particular order.

Photo of the static and pitot lines running to the backup instruments.

Another view of the static lines.

As can be seen in the above photos, the static line from the tail cone goes into a T on the altimeter (located above the fan) from the T a line is run to a Y that is barely visible along the edge of the map box.. From the Y static lines are run to the vertical speed indicator above the altimeter and over to the airspeed indicator mounted in the center panel. The pitot tube only goes to the airspeed indicator and is attached to the port on the right side of the instrument (the one with the straight fitting).


The last two remaining items left to install for the avionics was the transponder antenna and the Garmin GTR 200 radio. With Mike’s help the transponder antenna was a snap to install after a little paint and primer was removed in the area where the grounding washer sits. The short stubby antenna is secured by one nut onto the belly of the fuselage. Mike inserted the antenna from below and I placed the lock washer on the threaded shaft that entered the center tunnel and then tightened down the screw and placed the antenna wire on the BNC connector. The Garmin GTR 200 radio was also a snap to install it just slides into its mounting tray and is locked in place by placing a 3/32" Allen wrench (think that was the right size) into a tiny hole on the front panel near the right edge of the radio and turning the locking screw clockwise. You will see the radio get pulled in a little farther then the screw gets tight. For those builders wondering why the radio was installed last, it was only because the static line was looped around under the radio and needed to be installed into the T fitting on the altimeter. It was very convenient to be able to reach down through the opening in the radio’s mounting tray to insert the static tubing into the T.


The moment of truth …. “The smoke test”.  First the master switch was cautiously flipped On (with a fire extinguisher nearby) and there was no smoke or blown fuses! The SkyView went through its boot process and displayed three big X’s across the screen one for the ADHARS, one for the EMS and one for the GPS.  Not to worry this is normal because the hardware has not been configured yet. Prior to configuring the hardware the Dynon system FORCES the user to set up the N number for the airplane ... without establishing the N number the setup menus are grayed out and won't allow the user to get to the configuration menus. I don't have an official N number so I entered one of the two I have reserved and most likely to use.  After configuration of the hardware, the screen will look like the one below. I still have a red X for the GPS because I was inside the hangar due to rain and snow outside and the GPS can't acquire satellites.

The results after configuring the SkyView hardware and loading the updates and associated settings files.

AV-50001 Switch & Fuse Module Installed

Yesterday, the work session took an unexpected turn when it was realized it would be best to install the custom made mounting bracket for the controls before mounting the Switch & Fuse module. Then it was realized it would be best to install the labeling that was engraved for the controls now so they could be squared up using a jig of sorts. I opted to make separate labels for the controls so more of the powder coating would show, but that makes good alignment critical.  If I had it to do over I would consider making one large label with all the holes drilled in it. One of the down sides to the separate labels being used is the adhesive on the back is industrial … once it touches a surface for all intent and purpose it is ”there” not to be moved without destroying things.

A trip was made to the local big box store to pick up some dowel rods that match the diameter of the holes so the label could be slid down the dowel rod to stay centered on the hole. A piece of wood was used to align the top edge of the label before it was pressed onto the surface of the bracket.

Using a “jig” of sorts to help position the labels for the controls prior to sticking them in place on the home made bracket for the controls.

The labels turned out OK, but visually it may have been better to make one large plate instead of separate labels that ended up at various heights. But when the controls get mounted, it may not be as noticeable as it is now with nothing else to distract the eyes.

Mounting the modified bracket made for the control cables. The bracket allows the center panel section to be removed without the need to remove ALL the control cables from the engine compartment to do so. The modified bracket was mounted using AN525 screws and AN365 nuts.

The modified mounting bracket for the controls is installed and screws torqued to specs ready for the control cables.

In order to install the AV-50001 Switch & Fuse module the center panel section needed to be removed, yet again, because the module sits behind the center panel section. About this time Mike came by to loan me his battery charger so it can be placed on the battery when powering up the avionics for the first time. There have been quite a few upgrades made to the SkyView software which will need to be installed from a flash drive along with a few configuration files … so it is best to have the battery on a charger while all this is being done … not to mention the time that will be spent getting acquainted with the SkyView menus. While Mike was at the hangar he helped hold the Switch & Fuse module in place while I got a couple of screws into it to hold it.

Mike helping to hold the AV-50001 Switch & Fuse module in place while I get a couple of screws into it.

Once the AV-50001 module was screwed in place, the power connector was inserted and the WH-00031 connector was screwed in place on the back of the module. The fuse slots were populated with the correct fuses which, by doing so, revealed a discrepancy on the drawings. One drawing showed a 5 amp fuse used for the radio and another showed a 7.5 amp fuse. If installing the Garmin GTR 200 radio, as will be in the DOG Aviation RV-12, the builder should use a 7.5 amp fuse and NOT a 5 amp fuse as seen on some of the drawings. Section 42G-04 of instillation manual is for the Garmin GTR 200 radio and is the source of the info for the correct fuse size. (The older Garmin SL40 radio uses the 5 amp fuse).

Completed instillation of the AV-50001 Switch & Fuse module.

ADS-B Module Interference Issue Resolved

Yesterday afternoon was spent analyzing the best (or if not best, easiest) approach to resolve the interference issue between the backup airspeed indicator and the Dynon SkyView ADS-B module. Because the ADS-B module almost fit to begin with, rather than flipping it upside down and fabricating new mount or making a flat mounting plate that would allow the module to be offset, decided to make the attempt to lower the ADS-B module by cutting slots in the F-00045B ADS-B mounting brackets.


Because of the way the brackets were made, instead of making a vertical slot it was necessary to make the slots on an angle to keep the hole to edge distance acceptable. A Dremel tool outfitted with a cutter bit was utilized to freehand the slots. In addition to cutting the slots for the mounting screws, it was also necessary to relieve the forward end of the F-00045B brackets so they would clear the top of the F-00057 com support brackets. The right bracket was done first to see if it would work out …. as can be seen in the photo below it worked.

The right bracket was slotted as a proof of concept to see if the ADS_B module would fit under the fittings for the backup airspeed indicator …. as can be seen, slotting the bracket worked. The area that needed relieved was just to the left of the right mounting nut the bracket still touches a little so a black pen mark can be seen where more material needs to be removed.


Now knowing that the modification of the brackets would work, the left bracket was slotted as well. A keen eye on the photo below will reveal the right bracket was slotted deeper than the left this is because the airspeed indicator is on the right side of the instrument panel section so it needed a little deeper slotting to achieve the desired clearance.

Both the right and left F-00045B ADS-B mounting brackets after slotting.

After the brackets were slotted, the rivet holes for the nutplates were countersunk and the nutplates riveted in pace. By lowering the brackets I did create a minor issue ... in that the two mounting screws for the left side of the ADS-B module will need to be shortened a little because there is only about 1/8" of clearance between the nutplate and the frame for the Garmin GTR 200 radio.

Installing the ADS-B module … the two mounting screws sticking up will need to be shortened a little to clear the mounting frame for the Garmin GTR 200 radio.

Instrument Panel Sections In Place – Finally!

Here at DOG Aviation there is a knack for turning the seemingly simple into a time sucking abyss. Installing the instrument sections was no exception due to the powder coating. As frequent viewers of the blog have seen, the left and right panels have been in place for quite a while waiting for the center panel section, but it was all for not … when attempting to attach the center panel section it quickly became apparent there was no way the center section was going to fit. At first it appeared as though the powder coating in the holes of the left panel was preventing the panels from fitting together, so all the holes in the left panel were cleaned out with a jewelers file and the panels were mated again. Better but still not enough.

The center section screws were barely able to be screwed in … after installing a few screws to secure the center panel, it became quickly apparent that the screws for the right section would not align.


Long story made short … spanning two work sessions the panels were installed and removed at least four or five times before it became evident that the clearances are such that the panels will tolerate absolutely no powder coating along the edges that mate together … the screw holes just would not align correctly. So the panels were removed yet again and all the powder coating was removed along the mating edges with a long sanding block …  this solved the issue of the screw holes not aligning correctly. Once all three panels finally began playing nice together, two #19 holes needed to be drilled into bottom of the map box for screws. The instrument panel base has two predrilled holes which are used to match drill into the bottom of the map box.

About to use an angle drill to match drill the bottom of the map box to the instrument panel. The initial drilling was done with a #30 drill bit.


Once the bottom of the map box was drilled to #30 the right instrument panel section was removed so the two holes could be enlarged to #19. Glad I did it this way because both the #30 holes were very close to the forward edge of the map so a jeweler’s file was used to open up the two holes working away from the edge of the map box. The two holes in the instrument panel base were also opened up the same way then a step drill was used to round up all the holes.

Installing the right instrument panel section (hopefully for the last time) after drilling and deburring the mounting holes going into the bottom of the map box.


With the right instrument panel section screwed in position, I was eager to find out how bad the interference issue will be with the ADS-B module. Frequent readers of the DOG Aviation blog may remember a few months ago a test fitting was made and it appeared as though there may be an interference issue between the backup airspeed indicator and the ADS-B module. Today my fears were realized in that there is a clearance issue but fortunately it is not too bad … as luck would have it, the ADS-B module just barely touches the fitting on the airspeed indicator. Had the airspeed indicator been located just a little higher, all would be good … but I wanted it centered on the AP & Knobs Panel modules and knew there may be a clearance issue.

Photo of the ADS-B module hitting the metal portion of the fitting that screws into the back of the airspeed indicator. Lowering the ADS-B module about 1/4" will solve the issue.


After spending a half hour or so analyzing the situation, think I have figured out a simple solution to rectify the situation. Looking closely at the above photo … if one looks at the bracket the ADS-B module is sitting on and follows it to the left there is a nut there that secures the ADS-B mounting bracket to the com stack bracket. The nut is a little hard to see because it is in a shadow (should have used a flash) but my thought is to slot the screw hole in the bracket upward which should drop the bracket enough to clear the fitting on the backup airspeed indicator. There appears to be plenty of material to do this without creating any weakness. A problem to resolve during the next work session.