Completing Service Bulletin 16-08-24

Van's Service Bulletin 16-08-24 for the RV-12 involves inspecting the condition of the rivets attaching the WD-1204 left and right engine mount brackets to the F-1202B panel base. I’m very late to the party on this one, but decided to complete it while I’ve been in the mood as of late to get caught up on service bulletins. According to the service bulletin, two RV-12 owners reported seeing signs of lose rivets at the aft edge of the WD-1204 engine mounts. The inspection involves looking for any indications of wear including a smoky or greasy appearing film around the rivets. Any signs of rivet wear requires the removal and replacement of twelve LP4-3 rivets using a much stronger CherryMAX CR3213-4-2 rivet.

Ongoing inspections are to be made during annual condition inspections and if no loose rivets are found, log book entries are made indicating compliance with the inspection portion of this service bulletin and re-inspect at every annual condition inspection until the rivets in question have been replaced.

Service Bulletin 16-08-24 was issued just prior to my first flight, so did not act upon it and figured I would just keep an eye on the rivets and change them at my convenience … later down the road. Well, later down the road finally hit a dead end … because, although the rivets on the DOG Aviation RV-12 still looked pristine, decided since the F-1240 upper forward fuselage skin was already removed to replace the upper engine mount standoff, this seemed like the perfect time to complete Service Bulletin 16-08-24. Below is a screen shot from the Van’s document showing the locations of the affected rivets.

Screen shot of Service Bulletin 16-08-24 showing the locations of the twelve LP4-3 rivets that need to be removed and replaced with CherryMAX CR3213-4-2 rivets.

Admittedly, I have been putting this service bulletin off for quite some time because I knew it was going to be a totally uncomfortable and somewhat of a painful job … I was not disappointed, it was painful. To gain good visual and physical access to the heads of the LP4-3 rivets on the underside of the F-1202B instrument panel base requires being all scrunched up in the cockpit with feet on a seat, torso all twisted to get around the control stick so head and shoulders could slide into the leg wells. Unfortunately, I did not get any photos of myself all scrunched up inside the cockpit with the canopy closed on a 95°, 85% humidity day … but I was told my face got quite red while upside down drilling out the LP4-3 rivets. I can assure fellow builders the actual task of removing the LP4-3 rivets is a piece of cake if you plan ahead …. however, performing the task is just totally uncomfortable.

Here is a poor view of the heads of the heads of rivets on the right side of the F-1202B instrument panel base that need to be replaced. The aft two rows of three rivets closest to the nut securing the fan are the rivets that need to be removed … same rivets on the left side also need to be replaced.

Not wanting to climb in and out of the cockpit a bunch of times, figured I would amass all the tools necessary to complete the job … and set them up ahead of time. Also decided to use the pneumatic rivet puller so I would not have to set the CherryMAX rivets using a hand rivet puller in such uncomfortable conditions. A .090" piece of scrap aluminum was used to set a couple of spare CherryMAX CR3213-4-2 rivets into it using the ATS pneumatic rivet puller. This was done to verify it was set up correctly … I used 50 pounds of air pressure which seemed to work nicely.

Aircraft Tool Supply pneumatic rivet puller … this rivet puller has probably pulled well over 10,000 rivets and still works great! It has been a true workhorse.

Next a couple of LP4-3 rivets were set in the scrap aluminum and a drill stop was positioned on a #30 drill bit so the drill bit would only drill into the rivet head just barely enough to break it off.

This photo shows the two CherryMAx rivets set with the pneumatic rivet puller to verify it was setup correctly. Looking closely, just below the two CherryMAX rivets is a LP4-3 rivet that has had the factory head drilled off using the #30 drill bit and drill stop adjusted as shown.

In addition to the pneumatic rivet puller, the tools used to complete the Service Bulletin consisted of a trouble light, long hemostats, a powerful shop magnet (in case one of the ball/mandrels gets away), sticky tape of choice, a #30 drill bit with drill stop, hammer, and a finishing nail set used to pound out the rivets. I prepped a few rivet mandrels on the ScotchBrite wheel to smooth and slightly taper the ends so they fit easily in the center hole of the rivets (they bend easily, so you will likely need at least two or three). The mandrels work well to pound out the ball/mandrel from each rivet prior to drilling the head off.

Photo of tools used to complete Service Bulletin 16-08-24.

In order to provide better access for my helper to easily collect all the rivet pieces, felt it best to close the canopy … doing this allows unobstructed access to the backside of the instrument panel and the upper side of the instrument panel base. The air hose for the pneumatic rivet puller was run through the right air vent and a power cord for the trouble light run through the left air vent … this was done because I did not want the canopy frame to close onto the air hose or power cord which could easily bend the thin fragile canopy skirt which extends down from the canopy frame.  To complete the job, Bob (a fellow pilot who hangers a C-172 across from me) volunteered to give me a hand collecting all the rivet pieces. Thanks Bob!

The plan, which worked out perfectly, was to keep the canopy closed so Bob could have wide open access to the WD-1204 engine mounts and be able to easily collect all the rivet parts. To remove the ball/mandrel from each LP4-3 rivet, a prepped mandrel from a rivet was used as a pin punch and pounded into the center hole of each rivet from inside the cockpit, thus forcing the ball/mandrel out the backside of the rivet to be collected by Bob with the sticky tape wrapped around his fingers. The sticky duct tape worked quite well. We did need to use the magnet once because I told Bob to collect the ball/mandrel from the wrong rivet and ended up pounding out the ball/mandrel from a rivet he did not have his fingers on… totally my fault, but hey, I was looking at the panel upside down.

Next the 12 rivet heads on the bottom of the instrument panel base were drilled and removed using the #30 drill bit and preset drill stop. Prior to punching each rivet out, Bob attached a long pair of hemostats onto the shop head of the rivet … then from inside the cockpit, a finishing nail set was tapped with a hammer to remove the LP4-3 rivet body from the WD-1204 engine mount.

After briefly opening the canopy to get some fresh air and cool off a bit, it was time to get all scrunched up again to complete the job. The twelve CherryMAX CR3213-4-2 rivets were installed using a pneumatic rivet puller to set the rivets. The pneumatic rivet puller completed the job quickly and fortunately anticlimactically. I say that because when a CherryMAX rivet screws up, one has a real problem on their hands … safely removing them is far more challenging, so was very relieved their instillation went smoothly.

Photo showing the bottom of the right side of the F-1202B instrument panel base where the six CherryMAX CR3213-4-2 rivets were installed.

Photo showing the right WD-1204 engine mount where the aft two rows of rivets are now CherryMAX CR3213-4-2 rivets.

The actual task of drilling out the twelve LP4-3 rivets and replacing them with CherryMAX CR3213-4-2 rivets to complete Service Bulletin 16-08-24 is not at all difficult if a little advanced planning is used … but completing the task is truly uncomfortable.

Completing Service Bulletin SB 19-08-26 Rev 2

Service Bulletin SB 19-08-26 Rev 2 involves replacement of the RV-12’s WD-1201 nose wheel gear leg. There have been a few RV-12 aircraft that have developed cracks in the nose wheel gear leg’s tubing which were not visible during inspections until the nose wheel gear leg became seriously compromised.  My understanding is that the cracking begins at an internal structure not visible to the eye during inspections. Van’s has redesigned the WD-1201 nose wheel gear leg and “theoretically” made the area where the cracking began much more robust …. The new part number for the redesigned nose gear leg is now WD-1201-1-RTR.

The new parts required to complete the service bulletin can be ordered from Van’s using part number SB-19-08-26 for the RV-12 or SB-19-0826iS for the RV-12iS. The DOG Aviation RV-12 required part number SB-19-08-26. As can be seen in the photo below, the kit contains the new WD-1201-1-RTR nose wheel gear leg, two drill bushings, an Adel clamp (used to support the lower radiator hose) along with a screw and nut for mounting the Adel clamp.

Contents of the service bulletin kit part number SB-19-08-26 …. The new WD-1201-1-RTR gear leg, two drill bushings and an Adel clamp with mounting hardware used to secure the radiator’s lower coolant hose.

A closer look at bag 981 containing the drill bushings and bag 982 containing the Adel clamp and mounting hardware that comes when ordering part number SB-19-08-26.

Also of note: In addition to needing the drill bushings used to drill mounting holes into the new gear leg, it is also necessary to procure LONG 18" drill bits sized 1/8", 1/4" and 3/8". The 18" long drill bits can be procured locally or ordered from Van’s using part numbers TOOL-00040, 41 and 42 respectfully.

Before the fun begins, there will be a need to procure an engine hoist. A big thanks to Tom a fellow RV builder at the airport who was kind enough to loan me his engine hoist (Tom is building a RV -10 just about ready for a maiden voyage).  Hoisting the Rotax 912ULS engine is accomplished by placing straps around the intake manifolds and using the straps to hoist the engine up. Prior to hoisting the engine much, remove the thirteen AN3-4 bolts from the nose gear’s fuselage mounting plate. At this point, Van’s suggests placing a padded sawhorse under the tail cone. This is because it is necessary to hoist the engine until the tail cone contacts the sawhorse, then hoist a little more to allow the isolation dampers to separate from the nose gear’s firewall mounting plate. While hoisting the engine, there will be a point where most of the weight is off the mounting bolts … when that happens, remove the bolts and slide the WD-1201 gear leg assembly down off the firewall.

Using an engine hoist to lift the engine via a strap passed under the intake manifolds so the WD-1201 nose wheel gear leg could be removed. Thank you Tom for loaning me the engine hoist.

After removing the old nose wheel gear leg assembly, the nose wheel fork & tire assembly is removed and moved to the new WD-1201-1-RTR nose wheel gear leg. (Do not perform the nose wheel break-out force adjustment at this time because the gear leg will be removed again after drilling). The new gear leg and wheel assembly is placed in position and four AN3-4 bolts are used to temporarily attach the gear leg to the bottom of the fuselage. Next blocks of wood ¾” to 1” thick are placed between the engine mount and the gear leg’s firewall mounting plate and the hoist is lowered to place weight on the nose wheel which, in turn, pushes the firewall mounting plate tight against the firewall. Continue lowering the hoist so the engine mounts are now pressing on the blocks of wood …. Thus forcing the gear leg assembly even tighter to the firewall and ready for drilling. The wood basically simulates the thickness of the isolation mounts.

The 3/4" blocks of wood can be seen here sandwiched between the nose gear’s firewall mounting plate and the lower engine mounting point. The engine weight pressure on the wood helps keep the gear leg’s mounting plate pressed tight to the firewall for the drilling process.

Because the new WD-1201-1-RTR gear leg comes with the firewall mounting plate undrilled ... it is necessary to match drill the new gear leg to the existing bolt holes in the firewall. This is where the drill bushings come into play. The existing mounting bolt holes in the firewall are 3/8" so it is necessary to begin by drilling a much smaller 1/8" lead hole. The small drill bushing is inserted into the existing mounting bolt hole and the long 1/8" drill bit is inserted through the center of the drill bushing so the lead hole will be drilled perfectly in the center of the existing 3/8" hole. Sounds simple right? Actually, it is  … once one figures out how to keep the drill bushing from falling out of the bolt hole in the firewall. One option that works quite well is to slide a sleeve over the 1/8" and 1/4"drill bits so the sleeve can be pushed into the aft side of the drill bushing … thus keeping the drill bushing firmly seated in the 3/8" bolt hole during the drilling process.

This photo shows the three long 18" drill bits used to drill into the WD-1201-1-RTR nose wheel gear leg mount. Note the 1/8" drill bit has a piece of brake line slipped over it and the 1/4" drill bit has a piece of vinyl tubing slipped over it. The brake line and vinyl tube allows the person drilling to push on the back of the drill bushing thus keeping it firmly seated during the drilling process.

A couple of drilling tips:

First tip:  I like drilling with Boelube because it is drawn to heat. I figured it would be hard to use liquid Boelube so I used solid Boelube instead. If one looks closely at the photo above, you can see strategically placed painters tape on the 1/8" and 1/4" drills … the tape is used as a marker so the drill bits don’t completely penetrate the bushings as can be seen above ... this allows the tip of the bushing to be packed with solid Boelube. The sleeve can then be held at the tape location without the drill bit pushing the Boelube out when seating the drill guide into the existing 3/8" bolt hole in the firewall. After drilling a while, the drill bit/ bushing was removed and repacked with more Boelube.

Second tip: Drilling the hardened steel of the landing gear mounting plate requires slow speed. Suggest not using a high speed air drill. This is one place where a high torque battery operated hand drill set to slow speed is your friend. (Thanks Bernie for loaning me your drill). Work on one hole at a time so that a bolt can be inserted through the gear leg mounting plate to assure nothing will move while drilling the second hole.

Unfortunately, I forgot to get a couple of photos of the drilling in progress, but it required a firm forward force. In order for me to see where I was drilling, it required sitting in the left seat while drilling the right hole … and vice versa. After both holes are drilled into the WD-1201-1-RTR nose wheel gear leg, the engine is hoisted once again so the gear leg can be removed for deburring. After deburring the WD-1201-1-RTR nose wheel gear leg, it is placed back in position and bolted in place using the thirteen AN3-4 bolts. Then the engine is moved up or down as necessary to allow the bolts to pass through the WD-1201-1-RTR nose wheel gear leg’s firewall mounting plate and through the engine’s isolation mounts. The torque range for the mounting bolts is between 160 -190 in lbs. (13.3 – 15.8 ft lbs.).  However, only initially tighten to 160 in lbs. and if a castellation lines up with the hole in the bolt your done … if not, continue tightening until the next castellation lines up with the hole in the bolt and install the cotter pins.

The new WD-1201-1-RTR nose wheel gear leg mounted to the firewall.

All that is left to do to complete the gear leg replacement job is adjusting the nose wheel breakout force to between 18-20 lbs. … then drill the nose gear leg for the cotter pin using a #30 drill bit. For determining the breakout force I use a Rapala digital fish scale and run a wire through the bolt holes in the nose wheel fork so the fish scale can be pulled on the centerline of the wheel. After the breakout force is established, the last step is to drill new holes into the gear leg for the cotter pin that locks the castle nut in place. Below is a photo showing the Rapala fish scale being used on the old style nose wheel fork (which has been changed out long ago for the stronger newer one).

Setting the nose wheel breakout force using a Rapala fish scale. The nose wheel fork’s castle nut is tightened against the Belleville washers until the breakout force is between 18 – 20 lbs. … I ended up a tad over 19 lbs. Note: This is a photo showing the old nose wheel fork but the measurement method using the Rapala fish scale is the same … a wire passed through the fork’s axle holes and pulling the fish scale to determine the breakout force, then tightening the castle nut to create more friction until the breakout occurs within the acceptable 18-20 lb range.

Service Bulletin SB 19-08-26 Rev 2 completed on the Dog Aviation RV-12. The bird is now sitting on the new WD-1201-1-RTR nose wheel gear leg.

All and all, replacement of the WD-1201 nose wheel assembly was not as difficult as I had envisioned … although drilling the bolt holes while sitting inside the cockpit was a little uncomfortable.

Beefing Up The F-1254 Roll Bar Support Frames

Entering and exiting the RV-12 is not hard or extremely awkward for the pilot or passenger but there are places one naturally wants to place their hand for support such as on the F-1254 roll bar support frame. In some instances, applying body weight to the F-1254 support frame has caused deformation of the support frame or an outright kinking and bending of the metal.

The F-1254 roll bar support frame is the angled piece in the photo that also has a slot for capturing the canopy’s C-1206 guide plate. As can be seen in this photo, there is a large unsupported area adjacent to the seat which is right where there is a natural tendency to place a hand for support when entering or exiting the RV-12.

Builders have come up with various clever methods of stiffening the F-1254 support frame but when Van’s changed the RV-12’s fuselage design to support the Rotax 912iS engine, they also designed a stiffener that can also be used on a legacy RV-12 fuselage, which the DOG Aviation RV-12 has.

I’ve known about this weak spot ever since the initial flight and have instructed passengers not to place their hands on the weak area while entering or exiting the cockpit. I had already purchased a piece of angle aluminum that I was going to rivet onto the underside of the F-1254 roll bar support frame … but when I discovered there was a Van’s solution consisting of adding a stiffener of sorts, I ordered the new part. The Van’s part number is 12-01254A which comes as two stiffeners that when separated become a left and right part.

The F-1254A-L stiffener clamped in place on the pilot's side of the RV-12 and ready for drilling.

Instillation is not complicated. Van’s suggests breaking the edge on the upper portion of the F-1254A stiffener that will be riveted onto the F-1254 roll bar support which is what I did. The bottom edge that will be riveted onto the F-1234 canopy deck does not need to be broken, but it won’t hurt to do so. One needs to take a little care prior to drilling to align the stiffener then clamp and drill away.

Drilling the F-1254A-L stiffener onto the F-1254 roll bar support.

Completed instillation of the F-1254A-L stiffener riveted onto the F-1254 roll bar support and the F-1234 canopy deck.

The F-1254A L&R stiffeners were installed quite a long time ago on the DOG Aviation RV-12. While reviewing camera photos for an upcoming project, it was discovered the instillation process and photos were never posted on the Blog.

I would suggest all legacy RV-12 owners who have not taken it upon themselves to reinforce the F-1254 roll bar support frame with some sort of stiffener consider this easy to install solution from Van’s. It promotes piece of mind knowing one does not need to closely watch where passengers place their hands as they get in and out of the bird.

Chipping Away At The Small Stuff

With the DOG Aviation RV-12 nearing the end of the build, there are really no big tasks left to complete … however, that said there is quite a mound of small tasks that need to be knocked out to get ready for the air worthiness inspection only a week away. Quite a few tasks have been completed but the two that required a little tweaking are mentioned below.


Decided it was time to install the two shin whackers (the steps) which are passed up through an elliptical slot in the fuselage skin and bolted in place using AN4 bolts. I discovered the clearances were a little tight for both steps (probably due to the powder coating on the steps) which required filing away a little material from the fuselage skin. Came up with the idea of using O rings on the steps to protect them from being scuffed as opposed to placing  an anti-slip covering over the powder coating which would hide it's beauty. Two years ago some rubber O rings were installed as an experiment to see how well they would hold up ... not well they cracked, so switched to Neoprene O rings and they seem to be holding up well after over a year. Not sure how well these will hold up in actual use … if they don’t, will cut them off and switch to a traditional non-skid covering.

Installing the powder coated left shin whacker (step) was just a matter sliding the step up through a cutout in the fuselage skin and securing it to the F-1202F bulkhead using two AN4 bolts … once the opening in the fuselage skin was filed a little larger. A close observation will reveal neoprene O rings have been placed on the step so shoes don’t mar the powder coating. (I also have  some O rings for the hollow tube as well).


One of the items I had been putting off was trimming the aft edge of the canopy  on the left side. I have known about this for quite a while and had been putting it off but have now finally gotten around to tweaking the fit. This was a self-created issue, in that, it seemed having the canopy slightly skewed allowed it to fit better on the canopy frame…  so I went with that knowing the aft edge on the left side would likely touch the rear window, and it did. Coarse sandpaper was used to remove a little material from the aft edge of the canopy so the canopy could be closed without touching the rear window. Once the optimum fit was achieved, the aft edge of the canopy was sanded more using progressively smoother sandpaper until the edge was polished smooth.

Sanding some material away from the aft edge of the canopy on the left side so the canopy doesn’t touch the rear window when closed.

Working On Resolving Leaky Brake Fittings

Since completing the instillation of the rear window on Wednesday, have continued working on various small tasks that needed attention … the first of which, completing the trimming of the right & left flaperon’s inboard skins to obtain the required 1/8" clearance between the flaperons and the fuselage during full deflections of the flaperons.


Another area on the wings that required attention was in the vicinity of the F-1204R side covers for the blue electrical connectors. Unlike most of the other inspection covers on the RV-12, these covers do not seat into a joggle, so they protrude out from the side of the fuselage. The first time the clearances for the wings were measured, the F-1204R side covers were not installed, so it was necessary to remove a little material on both wings to obtain the required 1/8" clearances. A Dremel tool with a sanding drum was used followed by hand filing and smoothing with a 3M sanding block. I did not take any photos because photos of the process have already been posted in recent posts.


While the wings were off, decided to work on the brake fittings on the master cylinders that were discovered to be leaking after the engine run. The master cylinders and pedals are accessible with the wings off by leaning in over the canopy rail. For easier access, a bungie cord was used to pull up on the rudder pedals so the master cylinder was within easy reach. Bernie was available to lend a hand with draining the brake lines by opening up the bleeder valves at the calipers and capturing the brake fluid in a vessel while I pumped fluid out of the reservoir and brake lines by hand pumping the master cylinders. The fitting that was looked at first was the one that was physically dripping … which was the left brake master cylinder on the pilot’s side.

The pilot’s side master cylinder for the left brake has a leaking 90 degree fitting as can be seen here. This fitting was actually dripping a bit.


The fitting was removed counting the turns … it was in three turns. The fitting was lubed with fluid and clocked tighter and tighter by loosening then tightening the fitting progressively tighter until it had around a quarter turn or so left to go. At this point, the fitting was removed, and the threads carefully cleaned with solvent until they appeared free of fluid and debris, then Loctite 567 thread sealant was applied to the fitting and the 90 degree fitting was reinstalled and tightened to four turns without self-destructing … now the fitting is REALLY tight.

Snugging down the brake line to the pilot’s left master cylinder after tightening the 90 degree fitting one additional turn tighter. After this, a torque wrench was used to obtain the final torque on the fitting. Hopefully, one turn tighter will solve stop the drips because the fitting will never make it another full turn.


At this point, it was one down and two to go. The other leaks were on the co-pilot’s right master cylinder. They were not a physical dripping yet, but the fittings were definitely beginning to weep … so figured may as well fix it now.

Both the fittings on the co-pilot’s right master cylinder are showing signs of weeping.

The first fitting tackled on the right master cylinder was the upper 45 degree fitting … here again it was removed counting the turns and it too was three turns in. The same procedure as used above was used to work the fitting into the master cylinder one more turn and the brake hose was connected. However, when working on the 90 degree fitting on the bottom of the master cylinder began to run into issues. That fitting was screwed in 3 ½ turns to begin with. Using the previously mentioned procedure to progressively work the fitting deeper into the master cylinder discovered at the 4 turns point there is so much resistance that I feared if the fitting were to be made any tighter, it will either crack or break off in the master cylinder. I also suppose it may be possible to place the male 90 degree fitting in a die and screw it in tight and try seeing if another ½ turn can be obtained. However, have decided to first try another new 90 degree fitting and a different type of thread sealant that hopefully will do a better job of filling the voids in the threads … especially if I can’t get the new fitting to go in any further than the original one. So will have a little setback while waiting for the parts … but there are other things yet to do.

Tweaking The Fit Of The Eagle’s Wings

The instillation of the spar pins used to keep the wings secured has been a bit of a struggle both timed the wings have been mated to the fuselage. The first time when marking for the required 1/8” clearance between the wing skins and the fuselage, it was noticed the lower wing skins were touching the doublers that were installed on the sides of the fuselage … at the time it was thought this was probably the cause of the tight spar pins. Nope.


After removing excess material prior to mating the wings for the second time it was discovered the spar pins still were way too tight. Analysis of the situation with a mirror showed the right wing needed to go in just a little further so the bushings could align perfectly. Looking at the retainer block showed there was no clearance and it appeared the retainer block was preventing the spar from going in just a tad further. Thinking perhaps the rubber seals were causing an issue they removed but the spar pins were still way too tight.  The decision was made to remove the wings and sand 1/32" of material from the bottom of the block in the hopes it would allow the wings to be inserted just a tad bit further.

One of the two white F-1204R retainer blocks attached to each side of the center section. It appeared as though this retainer block was preventing the right wing from going inward just a tad further, so it will be removed for trimming along with the one on the right side. At this point the spar is tapered so removing just a tiny bit of material will allow the spar to be inserted just a tad further.

A line was marked on all four sides of both F-1204R retainer blocks so a 1/32" of material could be evenly removed from each of them.


The F-1204R retainer blocks were placed on a piece of sandpaper and sanded down while rotating the block often to make sure it was being sanded evenly. Material was slowly sanded away until the 1/32" red line was gone. The retainer blocks were reattached onto the center channel and the wings slid into the center channel. Ultimately, sanding a 1/32" off the F-1204Rretainer blocks solved the problem. The left wing was installed and both spar pins were inserted to hold the wing in position but not pass through the bushings. Next the right wing was slid into position and an instant difference was noticed, in that, one could feel the alignment was much better and after a little pushing and rotating of the spar pins they slid into the bushings of on the right spar. At this point it would have taken a soft faced mallet to seat the pins the rest of the way, now I was able to tap on the spar pins with the palm of my hand to fully seat them. Finally, a good fit!!!


Gee, before taking the wings off again to do a little more clearance filing on the right flaperon and to reinstall the gap seals, why don’t we roll the Eagle out of the hangar and start the engine? Sounds like all the makings for a big announcement in the next post.

Angle Of Attack Indicator Tubing Connection Finalized

Prior to installing the wings a couple of days ago the final routing of the Tygon tubing used for the AOA indicator was finalized. The Tygon tubing and Luer Lock quick disconnect connectors were purchased through McMaster Carr were covered in the following post many moons ago.


http://www.dogaviation.com/2012/12/left-wing-wiring-and-aoa-plumbing_21.html


The Tygon tubing for the AOA was routed behind the left electrical connector and coiled long ago … the tubing makes its way to the ADAHRS mounted in the tail cone. A hole large enough for a tiny grommet was drilled in the F-00032 side cover for the blue electrical connector just aft of the connector as can be seen in the following photo. The grommet was snapped into the hole and the Tygon tubing was routed through the hole and a Luer Lock quick disconnect was attached to the Tygon Tubing. The DOG Aviation procurement department also purchased protective caps for the Luer Lock quick disconnects so when the wings are off the fuselage, the connectors and Tygon tubing can be protected from dirt or insects.

A 3/16" hole was drilled into the F-00032 side cover aft of the blue electrical connector and a tiny SB-178-2 grommet was inserted so the Tygon tubing would not ride on the sharp edge of an aluminum hole. The one half of the Luer Lock quick disconnect can be seen here.

This photo shows the protective cap placed on the Luer Lock quick disconnect to protect debris from entering Luer Lock fitting when not mated to the Tygon tubing coming from the left wing.

Tygon tubing at the left wing root with Luer Lock quick disconnect attached along with a protective cap. After this photo was taken, a wire tie was used to support the tubing in place of the pull string it is currently on.


One of the reasons the wings came off again is because there were a few tight spots between the flaperon and fuselage … plus, the spar pins were VERY tight. After careful analysis, it appears the F-1204R retainer blocks could use a little trimming which will be covered in a future post.

Chipping Away At Small Tasks – Fuel Knob & Duct Seal Installed

Time spent at the DOG Aviation hangar over the last couple of days has been spent doing a little brainstorming for the mounting of the voltage regulator, dealing with the missing hole in the nose gear weldment and knocking out a bunch of small tasks which are not really noteworthy.


One task that had been on the back burner for a very long time was installing the VA-104 knob and F-1259G fuel valve handle onto the fuel valve. The VA-104 knob requires match drilling a #16 hole  ¾" to 1" deep down into the knob for a screw that will attach theVA-104  knob onto the F-1259G fuel valve handle. The knob is already countersunk for the mounting screw but has a small hole that needs to be enlarged to #16 so the threads of the screw will cut their own threads into the soft plastic knob.

Using a drill press to drill a #16 hole 3/4" down into the VA-104 knob for a screw.

After the hole was drilled, the VA-104 knob was screwed onto the F-1259G fuel handle and the assembly was mounted onto the fuel valve using a clevis pin, a couple of washers and a cotter key.


Another small task completed involved installing the rubber seals onto the lower cowl’s duct interface. Three pieces of rubber seal material are cut to lengths specified in the plans and are “glued” onto the duct interface using high temperature silicone. The longest of the three pieces makes a 90 degree bend around the lower portion of the duct interface and it requires clamping to keep the seal tight to the bend while the silicone cures. A thin metal strip formed to the bend on the duct interface was made to keep the rubber seal tight  to the curve when the clamps were tightened.


Prior to applying the high temperature silicone, the mating surfaces on the duct interface were sanded and cleaned with denatured alcohol. To minimize the potential for a mess occurring the area adjacent to the duct interface was masked off with painters tape. The sides of the duct interface received a coating of high temperature silicone that was spread evenly using a wooden tongue depressor. The longest of the three pieces was installed first and clamped so the seal would stay tight to the duct interface in the area of the bend.

Checking the fit of the last of the three pieces of rubber seal prior to slathering the duct interface with high temperature silicone.


The plans instruct the builder to insure there are gaps strategically placed where the rubber strips are adjacent to one another to allow for the rubber to spread out when compressed without bunching up on the adjacent rubber seal.

Completed instillation of the rubber gap seal onto the lower cowl’s duct interface.

Decided it would not hurt to use a few wooden strips to help keep the rubber duct seal tight to the duct interface as the silicone cures, so some were clamped onto the duct seal.