Completing Safety Directive SD-00001 Replacement Of Trim Servo Motor

A potential safety issue has been identified with RV-12’s that have the Ray Allen ES MSTS-T3-7A-2 trim servo motor installed. The issue involves the threaded portion of the trim servo motor shaft just forward of the AN315-3R lock nut that secures the AN665-21R clevis. The shaft is bending and, in some very rare cases, snapped altogether. The service directive requires mandatory replacement of the ES MSTS-T3-7A-2 trim servo motor with an upgraded Ray Allen ES MSTS-B6-7T-165 trim motor if the shaft is determined to be bent … or after 1000 hours of flight time.

Drawing from Safety Directive SD-00001 showing the location of the fatigue area.

The replacement Ray Allen trim servo motor has a part number of ES MSTS-B6-7T-165 and MUST to be installed with a bushing (Van’s part number BUSH-BS.188X.313X.222) that slips over the short threaded area of the shaft preventing the shaft from bending. Van’s also suggests when replacing the trim servo motor to also replace the F-1287A servo mounting tray with the newer F-1287A-1 mounting tray. The new F-1287A-1 mounting tray supports the DB9 connector Van’s has switched to … replacing the micro-Molex connector (problematic for some builders not having the proper crimping tool for the tiny pins) used on legacy RV-12’s.   When switching to the new F-1287A-1 mounting tray, you will also need to order an additional AN315-3R nut and Bag 2670 from Van’s which contains the male and female electrical pins, bodies for the new DB9 electrical connectors along with the necessary mounting hardware, plastic bushings and some rivets.

Drawing from Safety Directive SD-00001 showing the new ES MSTS-B6-7T-165 trim motor, bushing BUSH-BS.188X.313X.222 and AN665-21R clevis.

The decision was made that it would be better to take the approach of being proactive rather than reactive so decided to change out the trim motor …. Especially because, to Ray Allen’s credit, the company is offering RV-12 owners a substantial rebate if exchanging the old trim motor for a new one.

The DOG Aviation RV-12’s trim servo motor did not have a bent shaft. However, decided to make the exchange anyway and not need worry about the trim servo motor shaft bending issue anymore. Plus, I liked the idea of switching over to the new F-1287A-1 mounting tray which supports a DB9 connector to replace the micro-Molex connector.

New F-1287A-1 mounting tray which needs to have the doublers cut away and riveted onto the servo tray. Also, my finger is pointing to the new mounting flange for the DB9 connector.

After separating and smoothing the edges of the servo tray parts, they were primed with SEM primer and top coated with white paint for extra protection. Van’s calls for LP4-3 rivets to assemble the doublers onto the servo tray, but I used solid AN470AD4 rivets instead for the assembly. Next the plastic bushings are installed and filed down so they just clear the servo tray. (This is the same process as used on the original servo tray … in fact, I probably could have gotten by using the plastic bushings from the old servo tray).

Below is a photo of the new Ray Allen trim servo motor on the right and the old trim servo motor on the left. The three most notable differences on the new motor are … the round brass portion of the actuator that the new brass bushing will seat against, only four mounting holes as opposed to the six on the older unit and if one looks closely, the four corners of the case are scalloped a little.

Original Ray Allen ES MSTS-T3-7A-2 trim servo motor on the left and the replacement Ray Allen ES MSTS-B6-7T-165 trim servo motor on the right.

On the original trim motor instillation, Van’s covers the trim motor’s mounting flanges with doublers … but they are not called for on the new trim motor. I like the idea of the doublers because the trim motor’s mounting flanges appear to be just a tough plastic. Unfortunately, because of the scallops on the case of the new trim motor the old doublers can’t be used. I tried to file the correct profile in one of old doublers and was not happy with the results … because of the center hole in the old doublers, it leaves a very thin doubler in the area of the center hole.  Although not called for, I decided it would not hurt to just make a pair of doublers as can be seen in the photo bellow.

After trimming the old doubler (top of the photo) to fit the new trim servo motor, one can see how thin the metal is around the center hole (which is not on the new Ray Allen trim servo motor). So a new doubler (bottom of photo) was fabricated to mount the new trim servo motor in the F-1287A-1 mounting tray.

The new Ray Allen ES MSTS-B6-7T-165 servo trim motor installed in the F-1287A-1 mounting tray with my handmade doublers added for good measure.

For the final assembly, the forward threaded shaft temporarily receives two AN315-3R nuts which are tightened together or "double nutted", as they say. The nuts are temporarily used so a wrench can be used to hold the shaft from twisting and torqueing the internals of the trim motor when the AN665-21R clevis is tightened against the bushing. Prior to final assembly Van’s wants the clevis to be 15° from vertical when dry fitting the parts together using only fingertip pressure.

Two AN315-3R nuts are used to double nut the servo motor’s shaft so a wrench can keep the servo motor’s shaft from twisting and possibly damaging the servo when the bushing and AN665-21R clevis are tightened together.

The bushing in the above photo is slightly longer than necessary. To insure a proper fit, Van’s recommends using a drill press with some sandpaper to remove a little material at a time from the bushing so the bushing’s edges remain square. This is one place you don’t want to do any hand filing because Van’s wants the bushing to be a tightly mated fit between the trim motor and the clevis. Material is removed from the bushing until the slot in the AN665-21R clevis is approximately 15° degrees BEFORE vertical when the clevis is hand tight to the bushing. Note: Go slow! … only remove a few thousands at a time because it doesn’t take removing much material to make quite a difference in the positioning of the clevis ( I almost over did it on the second cycle to the drill press where I removed quite a bit more material than I did the during the first cycle). When a finger tight dry fit 15° shy of vertical is achieved, the bushing is ready for final assembly. Permanent red Loctite thread locker is applied to the aft threaded portion of the trim servo motor shaft and while holding a wrench on the double nuts to prevent the shaft from twisting, the clevis is threaded on further beyond the 15 degree point where it should become snug as the clevis reaches its proper vertical orientation.

Completed trim servo assembly ready for electrical connections and final instillation. Note, the two AN315-3R nuts are not yet removed from the forward threaded portion of the Ray Allen servo motor. The two nuts need to be removed at this point prior to installing the assembly back on the RV-12.

As previously mentioned, the new F-1287A-1 servo tray is designed for use with a DB9 connector. Female pins are attached to the wires coming from the trim servo motor and male pins are attached to the wires exiting the tail cone. There is a small change in the colors of the two power wires going to the new trim servo motor (the three trim position wires remain the same colors). The old trim servo motor power wires are both white … the new trim servo motor uses a white and a gray wire. Before permanently installing the wires into the DB9 connector bodies, I thought it best to use a 9v battery to make sure the new motor moves in the same direction as the old motor did … doing this insured the two white wires (servo trim motor power) exiting the tail cone will be connected to the new trim servo motor so motor movement is the same as the old trim motor. After the correct motor movement was established, the trim motor power wires exiting the tail cone were marked. Next, the pins were inserted into the DB9 housings. Van’s suggests sealing all the wires with silicone RTV so that was done prior to final assembly.

After the silicone RTV cured, the DB9 connectors were installed onto the F-1287A-1 trim servo tray. While trial fitting the connectors together, I noticed the DB9 connector was not fully seated. Upon a little investigating it was determined that because the male DB9 connector from the tail cone rests on top of the F-1287A-1 servo tray which has approximately a .060" or so of thickness, the standard sized threaded barrels are a tad too long … so I removed .060" from each threaded barrel and now have a fully seated DB9 connectors (If one chooses not to do this, it is not a big deal. However, I wanted my connectors fully seated and it was easy to accomplish just by removing a little material from both threaded barrels).

The DB9 connector #4 mounting hardware is NOT a piece of cake to install. Access is limited and the use of the tiny #4 MS21042 all metal hex stop nuts makes instillation a real hassle. The hex stop nuts are slightly egg shaped so they really grip the pan head screws … the problem is they grip just a little too tight when trying to install in such close quarters using a 5/32" wrench and only being able to tighten one flat at a time. I finally resorted to placing the head of the screw in a vice and running the metal stop nuts on and off a couple of times using CorrosionX as a lubricant to reduce the bite. The other issue I ran into was my long thin Philips screwdriver was 70 miles south at the southern outpost, so I needed to cobble together another way of accessing the #4 Philips screw heads from above the stabilator while using the 5/32" wrench from underneath the stabilator. Standard Philips screwdrivers are too short to accomplish this task when working by yourself. Below is a photo showing a drawing of how the DB9 connector is to be mounted onto the F-1287A-1 servo tray and the Rube Goldberg use of tools to fashion a way to get on the heads of the #4 Philips mounting screws from above.

Lacking immediate access to my very long thin Philips screwdriver, a Rube Goldberg assembly of various tools from the tool box was used to devise a way to hold the #4 Philips screws from above the stabilator. The photo also shows the drawing for mounting the DB9 connector.

Completed instillation of the new Ray Allen ES MSTS-B6-7T-165 trim servo motor, F-1287A-1 servo tray with the DB9 connector in place. Per Van’s instructions, silicone RTV is applied to the wires to seal the connector.

With the exception of dealing with the #4 mounting hardware for the DB9 electrical connectors, swapping out the RV-12’s trim servo motor went smooth and is not a daunting task. However, one does want to be careful when using the drill press to remove material from the bushing. Go slow and only remove a little material at a time to creep up on that 15° sweet spot.

The Eagle Receives A Rudder Trim Tab

During the second test flight where the RV-12 was flown for over an hour and away from the home field’s traffic pattern, it was noticed there is a yaw component that needs addressed. To keep the airplane flying without yaw, it required a constant pressure on the right rudder. This is not unusual for a RV-12 without rudder trim … in fact, I would say it is the norm. As mentioned in a previous post, this was expected because I can’t remember seeing any RV-12’s at Oshkosh that didn’t have a trim tab or a wedge on the left side of the rudder. Van’s now has a trim tab available for the RV-12, but unfortunately it came out after the DOG Aviation RV-12’s rudder was completed.


A few weeks ago I ordered a bunch of goodies for the RV-12 such as a canopy cover, sun shade and a trim tab which will be installing now before the temperatures plummet … I wanted to use AKZO primer which is temperature sensitive, so instead of flying more at this time, we are spraying paint. The part number for Van’s trim tab for the RV-12 is R-01220 … the trim tab comes predrilled and pre-bent for the amount of trim that is typically needed at cruising speeds to achieve flight without yaw.

The pre-bent R-01220 trim tab and associated AD-41-ABS rivets used for instillation.

Installing the R-01220 trim tab on a completed rudder requires the removal of one rivet … the lower aft rivet on the left side on the rudder. Prior to removing the rivet and begin drilling, decided to prime the mating area first because the temperatures were forecasted to get much colder than would be suitable for the Akzo epoxy primer to cure properly. The trim tab was held in position and a line was traced around the trim tab so the area could be masked off and sprayed with primer along with the mating surface on the trim tab.

After placing the trim tab in position, a line was traced around it to denote the area that would require masking and scuffing with a ScotchBrite pad.


A one ounce batch of primer was mixed up and the RV-12 was rolled outside and the primer was airbrushed onto the rudder and trim tab along with a couple of other small parts that I want to install in the future.

Akzo primer was airbrushed onto the surface of the rudder where the trim tab will be installed.

As mentioned above, the lower aft most rivet on the left side of the rudder requires removal so the mandrel requires being pounded out so the rivet can be drilled and removed. Those following the DOG Aviation Blog know flush rivets were used during construction, so the rivet being removed is a flush rivet … this will require dimpling the corresponding hole in the trim tab. All the remaining holes that will be drilled will NOT be dimpled because the rudder is now built and there is no access. Also, the rivets are so close to the trailing edge that there is not room for the dimple dies … so the trim tab will only receive one dimple where the flush rivet is being removed and the remainder of the rivets will not be flush.

My finger is pointing towards the only rivet that requires being removed. This rivet hole is used to orientate the trim tap in the correct position while match drilling the remaining holes into the rudder. Because a dimple already exists here, the trim tab will be dimpled only at this location.


Not wanting to just pound on the rudder with a hammer while the rudder was on its stop, decided it best to ask for assistance … so asked Bernie if he could come by the hanger for a few minutes to give me a hand. Bernie held a rag covered block of wood on the right side of the rudder on the rib opposite of the rivet being removed. I used a hammer to pound out the mandrel in the center of the rivet using a mandrel from another rivet that was tapered on the end a little on a Scotch-Brite wheel. Once the mandrel was removed, the head of the rivet was drilled until it popped off so the remaining portion of the rivet could be pushed in clear of the rivet hole. After the rivet was successfully removed, the F-01220 trim tab was secured onto the rudder with a Cleco so the bend line on the trim tab could be aligned with the aft edge of the rudder. Once in position, the trim tab was taped in place so it would not move while drilling.

Match drilling the rudder trim tab to the aft left side of the rudder. Notice the drill has a drill collar. It was adjusted to only allow the drill to penetrate just a little deeper than the skins so the drill bit would not hit the opposite side of the rudder.


After drilling, the rivet holes in the trim tab and the rudder’s skin were deburred. To install the R-01220 trim tab, the lone dimpled hole received a flush rivet and the remaining nine rivet holes received the AD-41-ABS rivets supplied with the trim tab.

Using the hand rivet puller to rivet the F-01220 trim tab onto the RV-12’s rudder. The lower left hand rivet is a flush rivet because the rudder was already dimpled at this location … the remaining nine rivets are AD-41-ABS rivets.

Completed instillation of the F-01220 rudder trim tab on the DOG Aviation RV-12.

Riveting Of Tail Cone Fairing Nutplates Completed – Almost

Over the past few days there have been just a couple of very short work sessions, but have been able to finish dimpling all the nutplate rivet holes on the tail cone. Fortunately, access was good and all twelve nutplate rivet holes on the lower portion of the tail cone were dimpled using the pneumatic squeezer.

Riveting tail cone fairing nutplates onto the lower portion of the tail cone.

For riveting the nutplates, I choose to use a no hole yoke because it offered more clearance for riveting the nutplates on the upper portion of the tail cone in the vicinity of the rudder horn and rudder cables … it worked out quite well.

The no hole yoke sets the rivets without the use of a die on the yoke and is also shaped differently so it offers more clearance.

All the nutplates on the lower portion of the tail cone are now installed.

The four rivet holes that needed to be dimpled using the C clamp will need to be riveted using a rivet gun because of clearance issues. Of course, one could always remove the vertical stabilizer and the stabilator and there would not be any issues. I have elected to work around them so will use a rivet gun and bucking bar to set the remaining four rivets … the two rivets closest to the vertical stabilator and the two rivets closest to the upper skin of the stabilator.

Using the rivet gun and bucking bar to rivet the nutplate rivet closest to the vertical stabilizer.

Was able to finish off setting all of the rivets for the nutplates with the exception of the two closest to the stabilator. Because of the location, did not feel comfortable attempting to do this by myself, so will enlist Bernie to give me a hand later today to set the remaining two rivets thus putting this chapter of the build to rest.

Dimpling Tail Cone’s Nutplate Holes Presents Challenges

Although a relatively short work session did made some forward progress on the nutplates for the tail cone’s fairing despite running into a few clearance problems. Work this session involved drilling the rivet holes for the six nutplates that secure the upper half of the tail cone’s fairing. The drilling of the nutplates for the upper half of the tail cone’s fairing was accomplished using the same drilling methods covered in the previous post for the lower half of the fairing.

This portion of the tail cone’s skin is flat, so drilled the nutplate holes from the outside using the angle drill outfitted with a #40 drill bit.


After all the rivet holes for the nutplates were drilled, they need to be marked for positioning then removed for deburring and dimpling … this was done one nutplate at a time so labels did not need to be made. Marks were placed on one of the nutplate's rivet holes in the tail cone's skin and the corresponding rivet hole on the nutplate to identify positioning for reassembly. I quickly ran into issues when attempting to dimple the nutplate rivet holes closest to the vertical stabilizer … the pneumatic squeezer could not get onto the rivet because the squeezer’s yoke interfered with the rudder’s horn. I tried a couple of different yokes to no avail and a hand squeezer …. shy of removing the rudder (not an option), nothing seemed to work. After a little brainstorming, came up with the idea to set the dimples using a C clamp.

Because there was not enough clearance to use the pneumatic squeezer for setting the dimple in the nutplate rivet hole closest to the vertical stabilizer, opted to use a C clamp to compress the dimple dies together. Although a little scary, took it slow and this method ended up working out quite well.

After using the C clamp to squeeze the dimple dies together, the dimple was checked with a rivet … this rivet is sitting flush with the skin … time to move on. The red marking denotes nutplate positioning for reassembly.


Working from the top down, the nutplate rivet holes in the tail cone were dimpled along with the corresponding nutplates. All was going well until reaching the lowest rivet hole closest to the stabilator. Even with the pneumatic squeezer sitting on the skin of the stabilator, there was not enough room to get the dimple dies close to being squared up … so resorted to using the C clamp again to make the dimple.

The C clamp was once again enlisted to create a dimple … this time for the nutplate rivet hole closest to the stabilator.

Did not have the time to finish off all the dimpling so will finish that off during the next work session. I can see now riveting the nutplates onto the tail cone skins at the tight spots may present a challenge … sure all the tail feathers could be removed to allow for unobstructed access, but would prefer not going that route if I can find other methods that work.

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.

Horizontal Stabilizer Installed – What Worked – What Didn’t

The Rotax 912 engine needs to come out of the box very soon … prior to installing the engine, the carburetors and intake manifold need removing in order to install the FF-1207 fiberglass cooling shroud. I would prefer doing that work on a work bench but the second workbench has the horizontal stabilator sitting on it. So prior to digging into the engine, wanted to get a couple of tasks completed. First, I plan to paint the FF-1207 fiberglass cooling shroud prior to installing it. However, the fiberglass was really rough and porous, so a mixture of epoxy resin was thinned with Acetone and slathered onto the cooling shroud to soak into all the nooks and crannies … this will create a much smoother surface for the paint and hopefully better visual appeal. After the shroud was coated with the thinned resin, it was placed into the hot box to cure. Now it has dried and is looking for the most part, very smooth … so thinning the epoxy with Acetone worked great for getting rid of all the roughness.

After a mixture of epoxy resin was thinned with Acetone, it was slathered onto the FF-1207 cooling shroud to fill in all the roughness of the glass weave.

Second, and more importantly, I need a workbench freed up so the engine can be placed on a sturdy surface while working on it, as opposed to working on the floor … and that meant installing the horizontal stabilator to free up the workbench it is sitting on.  The plan: Tilt the tail cone down to meet with the level of the horizontal stabilator, roll the workbench into position and bolt it up. I told Bernie about my plan to make a wooden block with a V notch so the front tire would not roll and then place wood underneath it to lift the wheel and drop the tail cone so I could keep the stabilator on the workbench and only need one helper. Bernie came up with the great suggestion of using a cement block he had and letting the wheel sit in one of the holes. This worked great to meet my low workbench … in fact, had to also add one piece of 3/8" plywood under the block to get it perfect.

The nose wheel placed in the hole of a cement block to lower the tail cone worked perfectly. Thanks for the idea Bernie.

Tail cone lowered to meet with the level of the horizontal stabilator sitting on the workbench.

So far so good … next the long counterweight arm was slid into the sockets on stabilator and bolted in place. This makes the stabilator want to roll from all the weight and from this point on things became a challenge and an exercise of patience. The workbench was rolled forward until it almost touched the tail cone and the stabilator was slid forward and aligned with the bearings as best as possible.

Now for what did not work. I was hoping there would be enough access to install the bolts and washers from up above. This is where the wheels fell off and that proved to be pure folly because there is not much room to work yet alone see while bent over the top of the horizontal stabilator. At one point I climbed up onto the workbench and although the view was better it was truly difficult to even get the bolt started yet alone worrying about the washers. Finally got a bolt through the bearing on the left side without any washers just to hold positioning.

Getting back on track, it was determined the task would be far easier to complete if done from below, so with a bolt holding positioning on the left side I commandeered Mike’s creeper from the hangar next door (thanks Mike T.) and accessed the situation from bellow. Seemingly there was more room when Mike K. rotated the stabilator a little and held it so I was able to easily get a bolt fed through the inboard washer. To hold the washers, a wooden pop sickle stick was filed to have a curve on the end that matched the washer, then masking tape was used to adhere the washer onto the stick. From below the view was better and could see to easily get to the bolt in the hole, then using the pop sickle stick, placed the washer in position and slid the bolt through the washer and ultimately into the bearing when Mike K. gently moved the assembly around. I had not glued the outboard washers as suggested in the plans but found that using the stick to hold the washers the outboard washers were easily slipped into position … however a thin strip of metal was needed to push on the edge of the washers to position them correctly so the bolt would capture them.

Having the bolt and washers for the right side bearing in place, it was determined that repositioning the workbench only underneath the left side of the stabilator would give me more room to work on the bolt and washers for that side. Mike moved the stabilator until a neutral point was found that allowed me to remove the bolt that was temporarily slid through the bearing to hold position. The pop sickle stick trick was employed again and with a little patience the bolt and washers were in place. For those builders interested in the washers used … the inboard washers ended up being AN960-416 and the outboard washers were AN960-416L.

A proud moment - the horizontal stabilator is finally installed. Could not have done it without Mike K.’s help. Thanks Mike!

To finish off the horizontal stabilator instillation the anti-servo tabs were installed. The hinges need to have 3/4" of the end bent to 90 degrees … this is so the hinge pins can be safety wired onto the stabilator.

Using a seeming tool to bend the end of the anti-servo tab hinge pins to 90 degrees.

Installed the left anti-servo tab first and while installing the right side, discovered the hinge pin needs to be installed from the bottom. The hinge pin for the first anti-servo tab installed can be inserted from the top or bottom … however, which ever anti-servo tab is installed last the hinge pin needs to be inserted from the bottom. Ask me how I know.

Installing the hinge pin for the left anti-servo tab.

Installing the hinge pin for the right anti-servo tab - tghis needed to be done from below by deflecting the anti servo tab up to get clearance.

Completed tail feathers for DOG Aviation RV-12.