Com Antenna Short Wire Issue Resolved – Tail Cone Drilled For Nutplates

Following a suggestion from friend Mike, decided to try using a 90 degree BNC connector first as opposed to tearing out the entire center tunnel to gain access to the com antenna wire. Mike made the valid point lots of airplanes have 90 degree adapters (including his) so it should work just fine and will alleviate the need to move the com coax forward.  The 90 degree connector will add approximately .2db of signal loss to the antenna which in the grand scheme of things is not all that much. Fortunately, one of the local FBO’s had a spare connector for me to purchase.

This 90 degree BNC connector will eliminate the need for the elusive “cable stretcher” or tearing out the center tunnel to gain access to the com coax cable so it can be moved forward.

The 90 degree BNC connector installed on the back of the Garmin GTR 200 radio’s frame. This should only add approximately a little less than a quarter db of insertion loss.

Back to work the tail cone fairing … with the tail cone fairing still secured in position with Clecos, the #40 holes in the fairing were match drilled to a final size of #27 into the tail cone’s skin. All twelve mounting holes are drilled to #27.

Match drilling the tail cone’s fairing into the tail cone using a #27 drill bit.

While the fairing was removed for deburring, a little more filing and sanding was done to tweak the stabilator’s upper and lower skin … now there should be a 1/8" gap between the tail cone’s fairing and the upper and lower stabilator skins.

The tail cone’s fairing is secured onto the tail cone using 12 screws that screw into nutplates. The nutplates offer a little bit of a challenge because there really is not much room for drilling the tail cone’s skins for the nutplates from the inside out. Van’s suggests bending the nutplates to conform with the curve of the tail cone's skin then drill using a long #40 drill bit … but I found that would place the drill bit at quite a bit of an angle for most of the holes.

A nutplate secured with a screw and a pile of washers ready to be drilled from the inside out.

I opted to get a little creative and used the 90 degree pneumatic drill. For the most part it worked well there was still a small angle but not as much as using the long #40 drill bit.

Using the pneumatic angle drill outfitted with a #40 drill bit to drill the nutplate rivet holes into the tail cone’s skin.

There were a couple of holes where the angle drill was hitting  stuff which created either a bad angle or total interference ... so for those locations, elected to drill one of the holes from the inside and use the drilled hole to Cleco a spare nutplate curved to conform with the outside of the tail cone’s skin so the second hole could be drilled from the outside. This worked out well. Because one hole was drilled from the inside and the other from the outside it should make the angular difference minimal even though it is on a curve ... especially after the holes are dimpled.

This nutplate location had one hole drilled from the inside … then a spare nutplate was curved to match the contour of the tail cone’s skin and secured on the outside of the skin with a Cleco so the second rivet hole could be drilled from the outside.

After all the rivet holes for the nutplates are drilled, the nutplates are to be marked so they can be placed back to the proper locations after removal for deburring. The builder also needs to identify two nutplates that will receive a little more attention … in that, a tap is to be run half way through them prior to being riveted in position.

The two nutplates my fingers are pointing towards require a tap to be run half way through them prior to being riveted. I’m guessing this is done because these two nutplates are fairly close to the stabilator’s bottom skin and this will make screwing the screws into the nutplate a little easier.

Tweaking The Tail Cone’s Fairing & Stabilator

Being at a temporary impasse when it comes to moving forward with the instrument panel, decided to continue making forward progress and work on the tail cone’s fairing while waiting for the center panel section.


Last fall when preforming the initial fitting of the tail cone’s fairing, Van’s plans suggest there should be at least 1/8"of clearance between the fairing and the stabilator and also between the trim actuator pushrod and the slot in the fairing. The clearances were less than optimum, so at that time marks were placed on the fairing and the stabilator skins where material would need to be removed. A Dremel outfitted with a sanding drum was used to remove the excess material followed by a file and sandpaper. The initial cuts on the fiberglass were made outside and unfortunately had to be completed inside when the forecasted monsoons cut lose.

Some material was removed already with the Dremel outfitted with a sanding drum. This still needs a little more work.

Using the Dremel from below to remove material from the stabilator so the sanding drum could not inadvertently skip across the stabilator’s skin. It was raining so hard outside the noise level in the hangar was deafening so ear protection was necessary.

Tweaking the gap between the slot in the fairing and the trim actuator pushrod.

There is still a little tweaking left to do, but it is almost there. Once the clearance issue is resolved, the twelve #40 holes in the fairing at the aft end of the tail cone need to be drilled to #27 and nutplates installed.

Brake Lines Completed & RAMI AV-17 Com Antenna Mounted

Today was an under the belly day by way of spending the better part of the afternoon on my back using Mike’s Jeepers Creeper to finish off instillation of the brake lines and installing the RAMI AV-17 com antenna. This is a job I had been putting off for warmer temperatures which we had a little of today.


The first task that seemingly took an eternity to complete was placing a wire tie around the two poly brake lines  that pass between the flaperon push tubes and securing them to the F-1204D center channel bulkhead between the two push tubes. I found this task quite challenging, it would have been easier if another person were helping from the other side of the bulkhead … but I was by myself. The challenge revolves around trying to wrap a 4” wire tie around the area between the two holes in the F-1204D bulkhead that the flaperon push tubes pass through … while at the same time capturing both brake lines and feeding the lose end of the tie wrap into the latch on the wire tie with pretty much one hand and a finger. You can see the area easily enough, but getting both hands there is another story. After a bunch of failed attempts, I finally got the wire tie latched only to discover I had missed one of the brake lines … another failed attempt.  My procedure clearly was not working well ...  so after a little brainstorming, came up with using a long hemostat to help feed the wire tie into the wire tie's latch. Ultimately this worked great, wish I had thought of it earlier.

This long hemostat saved the day … after the wire tie was passed though the opening in the bulkhead the hemostat was placed on the end of the wire tie so it could be directed into the latch.

Both brake lines tied together and secured to the F-1204D center channel bulkhead.

After the brake lines were secured to the F-1204D bulkhead, the fittings on the ends of the poly brake line were screwed into the fittings on the U-1203 gear attach brackets and torqued. Torqueing was another challenge but was finally able to find the right combination of crows foot and extensions to get the job done.

Brake line firings for the right brake that attach to the U-1203 installed and torqued.

The brake lines from the fitting on the U-1203 to each wheel cylinder is not going to be the standard Van’s supplied poly brake line … they will be the vinyl coated stainless braided Teflon hose from Aircraft Specialty. After both hoses were set in place, the hose fittings were torqued.

Torqueing the Aircraft Specialty Teflon brake line hose on the right brake assembly.

Upon finishing with the instillation of both the Aircraft Specialty brake lines, decided to continue working under the belly of the beast and sanded a little more primer away from the area where the R. A. Miller Industries AV-17 com antenna will mount then cleaned the area with Acetone. The reason for removing the primer is that even though the plans don't call for the doubler plate that comes with the antenna to be installed ... I opted to do so in the hopes of providing a better ground plane for the antenna. Mounting of the com antenna went fairly smooth after the first screw was installed but getting that first screw started and the tiny lock washers in place is a little bit of a challenge.

The RAMI AV-17 com antenna and associated mounting hardware.

 Since I had more than enough cable slack (still need to pull a few inches forward) I chose pull the antenna's coax cable through the hole in the bottom skin and place the rubber gasket onto the base of the antenna, attach the coax to the antenna and position the antenna on the belly of the RV-12. The antenna is mounted with four countersunk Philips screws and four tapered star washers on the outside and four lock washers and nuts on the inside the bottom skin.

The RAMI AV-17 com antenna installed on the belly of the DOG Aviation RV-12.

Now all that is left to complete the braking system is add brake fluid and bleed the air out of the brake lines ... which hopefully can be done in one step using either a hand pump or pressurized vessel to force fluid from the wheel cylinders up to the reservoir. This method seems to work well for RV's in general. The other item left to do is instillation of the pull cable for the parking brake.

F-00035 Right Panel Section Installed

Although not actually at the hangar, the better part of the morning was spent making a custom to scale template to take to an engraver so a custom panel label could be engraved for the RV-12’s fuel pump and left landing light switches. The engraver told me they have the ability to laser cut the label material, so wanted to have them cut the two rectangular holes in the label saving me the hassle of doing so. Unfortunately that required making a detailed scaled drawing with very accurate dimensions because there is a very limited amount of room on the panel for the label. Just prior to heading out to the engraver, received the longer screws for the altimeter so after visiting the engraver and dropping off the drawings for the labels, headed to the hangar.


The longer screws were used to complete the instillation of the altimeter in the F-00035 right instrument panel section. Prior to installing the panel section, a couple of fittings were screwed into the back of the vertical speed indicator and the altimeter for the static air fittings. Decided to hold off on installing the static tubing until the airspeed indicator is installed when the center panel finally returns from powder coating. At that time the final tubing lengths and angles can be sorted out … will be sure to post photos of the plumbing after the center panel section is installed.

Installing the F-00035 right instrument panel section with the backup altimeter and vertical speed indicator installed. The hole in the top of the panel is for the vertical card compass which will be installed last after all the work in the instrument panel is completed.

One Small Step Forward One HUGE Step Backwards

Got to the hangar yesterday in great spirits and left disgusted and in total despair. The only good thing that got accomplished was mounting of the ACK E-04 ELT’s remote control panel indicator onto the left instrument panel section with #4 black screws that the DOG Aviation procurement department ordered.

The ACK E-04 ELT’s remote control panel indicator mounted onto the left instrument panel section.

From this point on it was a downward spiral, seemingly every task I wanted to work on required something else to be completed first. Can’t mount the additional two panel switches for the fuel pump & left landing light because of waiting for labels (which will be placed under the switches) to get engraved. Can’t mount the right instrument panel because of waiting for longer screws to mount the altimeter. Can’t finish off mounting the ADSB module because the center panel is still not here so the airspeed indicator can’t get mounted so accurate clearance measurements can be made … it is going to be tight so the mounting method for the ADS-B module may need to be tweaked and would like to finalize that ASAP.


With not much else to do, wiring wise, it got me thinking about mounting the com antenna ...  so the com antenna was pulled out of the box and instructions perused noting the mounting instructions indicated the antenna should be mounted on clean bare metal. So got under the fuselage, reached in through the inspection cover and used some 150 grit sandpaper and Acetone to remove the Akzo primer. Builders may want to consider not priming this area because it can only be reached from one side and there is a stiffener in the way to contend with so sanding away the primer was a little bit of a chore … hind sight is 20/20. After checking with an inspection mirror to verify removal of the primer was successful, thought it would be a good idea to check the continuity of the coax cable from the connector on the Garmin GTR 200 radio’s mounting frame to the end of the cable.


This is where the afternoon turned into a day of despair, frustration and self-loathing. In the following photo one can see the end of the coax cable is a little too short at the instrument panel end of the cable to be attached onto the connector … it needs to be at least a couple of inches longer.

It was discovered the Garmin GTR 200 radio’s coax cable is not long enough to connect onto the coax fitting (one with the black protective cover) coming out of the back of the mounting frame for the Garmin GTR 200 radio. This will not be easy to correct.


The only good news is there is plenty of cable slack at the other end of the cable in the center section to pull a few inches back. The bad news this is a HUGE setback because to correct the issue, it will require a major disassembly of parts just to gain access to the coax cable.

On the left, my finger is pointing to where the black com radio coax comes out of the upper grommet in the center section and makes the tight bend down to go under the cable shoe attached to the flap handle mounting block. With that tight of a bend, there is no way to pull the cable forward without removing the flap handle/mounting blocks and the two push tubes.


Discovering the coax cable is too short is a HUGE setback because it will require a lot of disassembling and removing of parts in the center tunnel just to be able to get fingers around the coax cable. Both F-1265 push rods need to be removed so the entire flap handle/ mounting block assembly can be removed just to get the cable shoe out of the way. Will also likely need to remove the flaperon mixer assembly and of course cut most, if not all, of wire ties to free up the coax enough that it can be moved forward to the instrument panel the few necessary inches. This will be a problem left to be solved when it warms up a bit more so a T shirt can be worn while doing the work because a large amount of time will be spent crawling around inside the cockpit to correct this major faux pas.


There are bands on the cables and harnesses to denote where to position the wires at the grommets in the instrument panel base … so the band on my cable was either placed on it incorrectly or it moved while other cables were being installed. I sure wish Van’s would include measurements in their plans in addition to the bands on the cables … which tend to snag on the grommets and move easily.


This was one of those days where I packed up and left the hangar early in disgust.


Return from the future: Following a suggestion from friend Mike, decided to try using a 90 degree BNC connector instead of digging into the center tunnel to gain access to the com coax to move it forward a few inches. Mike correctly pointed out lots of airplanes use 90 degree fittings behind the radio, including his. The loss of a 90 degree BNC connector is approximately .2dB so in the grand scheme of things that is minimal.

The 90 degree BNC connector procured at a local FBO.

The com cable easily reached the 90 degree BNC connector attached to the Garmin GTR 200 radio’s mounting frame. The insertion loss of the 90 degree BNC connector should be less than a quarter dB … so should be good to go with this arrangement.

Instrument Panel Wiring Completed (Almost) SkyView D1000T Installed

Yesterday was a quite an uplifting day, warm enough to actually have the hangar door open for the first time since last fall and making some major progress on the instrument panel beginning with instillation of the remaining the wiring harnesses. This pretty much finishes up the wiring in the panel area with the exception of connecting five wires to the yet to be installed two panel mounted switches for controlling the electric fuel pump and left landing light. Will hold off installing the switches for the time being because of being in the process of having labels made that will go under the switches … similar to what Pete used on his RV-9A which was a really thin black plastic that when engraved, revealed white lettering. Pete has photos of his panel that can be seen here:  http://www.myrv9.com/Main/Panel.html.


One of the things that became quite evident a while back was that the Adel clamp Van’s has the builder routing all the wiring through is woefully anemic now that the DOG Aviation RV-12 has the Garmin GTR 200 radio and has added ADS-B plus the AP & Knobs Panels not to mention the extra room taken up by the shielded cables that were installed for the landing, navigation and strobe lights wiring. The Van’s supplied MS21919DG16 Adel clamp (1") in the photo below is just too small for all the wiring in the DOG Aviation RV-12.

The Adel clamp below my hand has a bunch of wires in it already and the wad of additional wires I’m holding in my hand also need to be passed through the clamp … not happening.


Somewhere in the drawings (may have been the radio instillation section), I read where Van’s said it is OK to increase the size of the Adel clamp if desired … I desired, so when placing an order for some other goodies last week, also decided to up the Adel clamp by two sizes and ordered a MS21919WDG18 (1 1/8") Adel clamp. Interestingly, it was still a little smaller than I would have preferred but all the wires do fit in it … barely.

The Adel clamp on the left is the 1" MS21919DG16 Adel clamp the clamp on the right is the larger 1 1/8" MS21919WDG18 Adel clamp … the business I was ordering from only had the wedge style clamp hence the W in the part number.


The plans give the builder the option of adding a nutplate to mount the Adel clamp or use a screw and nut. I decided on using a screw and nut and glad I did, here is why.  The decision was made early on to install all the wirings harnesses first then insert them strategically one at a time into the Adel clamp as opposed to keep screwing and unscrewing the Adel clamp’s mounting hardware as wires were added.


A tip for fellow builders that opt to use a nut and screw to secure the Adel clamp: Because the wires in all the harnesses need to curve down to go through the Adel clamp then back up again it is VERY difficult to populate the Adel clamp without it wanting to raise up to the point it was almost impossible to push it down to the base of the instrument panel. To solve this issue, a temporary screw was placed in the bottom eyelet of the Adel clamp to keep the clamp secured to the instrument panel base using a nut on the underside of the base. This did a good job of keeping the clamp in position while being populated with all the wires. Once populated, prior to removing the temporary screw, wire ties were wrapped around the wires to hold their position so the stuffed Adel clamp could be closed and secured without pinching any of the wiring. The temporary screw was removed and the clamp was secured by inserting a screw up from underneath and placing a washer and locknut on the screw.

The larger 1 1/8" MS21919WDG18 Adel clamp secured to the bottom of the instrument panel base with all the wiring harnesses passing through it … with all the extra wires and shielded cables, this thing is stuffed.

All the wiring harnesses are installed in the AV-50000A Interconnect module except for the ignition switch harness … and that is the next item to be installed.


My preference would be to install the center section of the instrument panel first, however, because the center section is still out for powder coating, decided to move on and install the left and right sections now.  Will leave the screws loose so there will be some play available if necessary when installing the center section.


A deviation will be made from the plans regarding the mounting hardware used to attach the panel sections to the instrument panel and canopy ribs. The plans would have the builder countersink the panel’s mounting holes and use Philips screws to attach the panel pieces. I want a different look so have decided to go with black button hex head screws with black nylon washers under the screws to protect the powder coating.

Attaching the left panel section onto the left canopy rib using black button hex head screws with black plastic washers to protect the powder coating.


After getting the F-00060 left panel piece secured in place, the AV-50002 Ignition & Start module was screwed onto the left panel section … once again substituting with the black button head hex screws and black nylon washers. The short wiring harness that connects the Ignition & Start module to the AV-50000A Interconnect module was installed in the last remaining connector completing the populating of the AV-50000A Interconnect module.

Securing the AV-50002 Ignition & Start module onto the F-00060 left panel section.


Next came the installation of the Dynon SkyView D1000T 10” touch screen which attaches to the F-00060 left panel section using 6 screws provided by Dynon found in the bottom of the box along with a 8Gig USB Flash drive and a test cable. Once the SkyView was installed, the 37 pin and 9 pin connectors were installed onto the back of the unit.

Installing the Dynon SkyView D1000T 10” touch screen onto the F-00060 left instrument panel section. Since I had black washers, placed them under the heads of the six mounting screws for good measure.

View of the back of the SkyView D1000T with both the BD-9 & DB-37 connectors attached to the unit.

Moved on to the F-00035 right panel section to prepare it for instillation. The map box door/hinge needed to be installed along with the map box door latch. LP4-3 rivets are called for riveting the door/hinge assembly onto the map box frame … part of the riveting was done prior to sending the assembly out for powder coating so all that was left to do was rivet the door hinge onto the map box frame.

Using the hand rivet puller to rivet the door/hinge assembly onto the map box frame.


With the map box assembly completed, moved on to begin working on installing the backup instruments. One of the unfortunate things about powder coating is that it partially fills screw holes and instrument holes, so the really tight fitting backup instruments would not fit into the holes until the offending material is removed. Had to use a jeweler’s file to remove the powder coating from the inside of the holes for the altimeter and vertical speed indicator. Discovered I did not order long enough screws for the altimeter because I used either the vertical speed indicator or airspeed indicator for measurements not noticing at the time that the altimeters case is much thicker where the mounting screws go. Was hoping to have this panel finished this work session but will need to hold off for a couple of days until the longer screws from Aircraft Spruce get delivered.

Backup vertical speed indicator installed into the F-00035 right instrument panel section using black brass hardware. Will need to get longer screws for the altimeter due to it having a thicker case in the area where the mounting screws are, so it only has one temporary screw holding it at the moment.


Will not be mounting the compass yet until all the rest of the panel work is completed … don’t want it subjected to possible magnetic fields from power tools or screwdrivers that have become magnetized ... so it will be the last item installed in the instrument panel.