Wednesday, April 29, 2015

Installed Baggage Corner Skin & More Wiring

Learning from the right side, when installing the left F-1273 baggage corner skin made life a little easier by removing even more Clecos from the side skin which made installing the closeout much easier. The loser side skin allowed more play and less friction making alignment and positioning no struggle at all.
Positioning the left F-1273 baggage corner skin so it can be slid under the fuselage’s bottom skin.
The left F-1273 baggage corner skin secured in position with Clecos.

After the F-1273 left baggage corner skin was secured with Clecos, looked ahead in the plans and the next step begins installation of the turtle deck components and rear window … which, if installed at this point in time, will make getting into the tail cone even more difficult than it will be otherwise. So will be hit the brakes on placing more metal on the fuselage for the time being and finish up running wires through the center tunnel then fall back and tidy up all the wiring from the tail cone forward with tire ties.

The only remaining wires needing to be pulled in through the center tunnel are the wires from the switches on the stick grips and the canopy latch switch wire. Decided to knock out the WH-W1114 canopy latch switch wire first … this is the wire that runs from Van’s newly added micro switch for the RV-12’s canopy latch forward to the instrument panel. Note: Some documents also refer to this wire as WH-00109, but one of the newer electrical schematic drawing calls this wire WH-W1114, so that is what I’m going with. Because the conduit for the cockpit lighting is already installed inside the roll bar, could not run this wire through that conduit … so a new conduit was made for the wire by cutting a 30" piece of 1/8" vinyl fuel line to pass through the roll bar. Next the WH-W1114 canopy latch switch wire was run through the center channel wiring conduit and up through the center tunnel to the instrument panel. According to the electrical drawing, at the instrument panel the WH-W1114 canopy latch switch wire will attach to pin 8 of the 37 pin d-sub connector labeled “Fuselage” on the WH-00046 wiring harness.
Feeding the WH-W1114 canopy latch switch wire through the center channel wiring conduit.

The only remaining wires left to run up the center tunnel to the instrument panel are the wires for the switches on the control sticks.  So that will be the focus of the next work session.

Sunday, April 26, 2015

Adding More Parts To The Fuselage/Tail Cone

The plan is to hold off on fully riveting the side skins onto the fuselage until after the rudder pedals are installed. The last time the side skins were on the fuselage a test was made to determine if the forward half of the side skins were not Clecoed, could the skins be easily flexed enough to allow access to install the rudder pedal mounting bolts? The hope is to  install the rudder pedals and tighten the fluid fittings without needing to crawl into the cockpit to tighten the hardware. There seemingly was enough room, so will try that tact when mounting the rudder assembly.

In the mean while, there is still plenty to do ... so continued adding parts onto the fuselage/tail cone assembly beginning with the F-1207E-L&R shoulder strap lugs. The lugs attach primarily to the upper skins of the tail cone but also tie into the baggage bulkhead as well. These lugs become the mounting point for the pilot and co-pilot’s safety harnesses and were machine countersunk last year for the flush rivets being used on the DOG Aviation RV-12.
Sliding the left F-1207E shoulder strap lug into the slot in the baggage bulkhead and securing with Clecos. The right shoulder strap can be seen in the foreground secured with Clecos and ready for riveting.
Using the pneumatic rivet puller to rivet the right F-1207E shoulder strap lug onto the top skin of the tail cone with flush rivets.

Decided this would be a perfect time to rivet the F-00062 ADAHRS stiffener in position. This stiffener was not part of the original RV-12 kits. However that has changed ... as Van’s began receiving reports of erratic movement of the ball in the Dynon SkyView turn coordinator and with the help of a couple of builders, Van's isolated the issue. The erratic movement was ultimately traced to prop-wash creating flexing and vibrations of the tail cone’s top skins in the area where the ADAHRS unit is mounted. The fix was to add a stiffener rib part number F-00062 just forward of the ADAHRS unit. This rib makes a HUGE difference in stiffing up the area where the ADAHRS mounts … so builders of older RV-12 kits will want to add this stiffener. I forgot to take a photo of the stiffener after it was riveted in place … but prior to riveting, the F-00062 rib can be seen in its approximate position in the fifth photo on the post dated 4/24/2015.
Riveting the F-00062 ADAHRS stiffener rib onto the upper skins of the tail cone just forward of the Dynon ADAHRS unit.

Prior continuing on mounting left F-1273 baggage corner skins decided it would be a good idea to place a dollop of silicone on the bottom skin to secure the AOA tubing on the bottom skin to keep it well under the flaperon torque tube which will be installed in the future. This needed to be done at this time because the baggage corner skin will close off easy access to this area.
AOA tubing set into a blob of silicone securing the tube to the bottom skin of the fuselage.

While the silicone sets up on the left side of the fuselage, moved over to the right side and began working with the right F-1273 baggage corner skin. The baggage corner skins close out the opening between the side skins and the fuselage’s bottom skin and sit UNDER  BOTH the fuselage side skin and bottom skin ... but OVER the tail cone skin. This skin was a bit challenging because the bottom skin has very little flex because only the outer row of rivet holes is open. The dimples for flush rivets make sliding the skin into position hard because the bottom skin has very little play. The baggage corner skin needs to be slipped up under the side skin about 1/2" higher than its final resting place so the bottom edge of the corner skin parallels the outer edge of the bottom skin ... then it can be slowly worked down and under the bottom skin.
Mike’s creeper came in handy to get under the fuselage to begin working the right F-1273 baggage corner skin under the fuselage’s bottom skin.

After winning the fight with the right corner baggage skin, decided this was a good stopping point for the day.

Saturday, April 25, 2015

RV-12's Tail Cone Mated To Fuselage!!

The last few work sessions have been in preparation for the mating of the RV-12's tail cone section onto the fuselage. Having gone off the reservation with regard to installing the electrical along with AOA, pitot and static air tubing plus mounting the Dynon ADAHRS unit into the tail cone prior to mating … there was a small element of concern that perhaps it may have been fool hardy to have done so.

However, I’m glad to report ... YES, it can be done! Although striving to not enter the tail cone at all, at the last moment I decided not to chinch up all the wire ties just in case it was necessary to move tubing or wiring. Ultimately that was not necessary, but probably still a good idea just in case. As such, I will need to extend myself into the tail cone to cinch up and clip the wire ties. Have also decided it may also be wise to add a little extra protection for the wires where the wiring bundle makes the bend aft from the backside of the F-1206A bulkhead onto the J channel on the left side of the tail cone. Don’t want vibrations to cause the edge of the J channel to chafe the wiring. So even though I will still need to reach into the tail cone, cinching and clipping the wire ties should be, for the most, part an easy task.

Mating the RV-12’s tail cone to the fuselage was an all hands on deck event. There were four of us … that seemed to be the perfect number. Jan (who is the only one of us that has been working out regularly in a gym) was given the task of holding and maneuvering the aft end of the tail cone.  Mike T. and myself stood on either side of the forward end of the tail cone to support and maneuver it into position. Mike K. went from side to side to flex the skins during mating, he also verified the skin overlaps were correct and the holes were aligning correctly. One good thing about the DOG Aviation RV-12 having dimpled rivet holes is when the dimples finally seated in place, the holes were, for the most part, instantly aligned.
Mating the tail cone was an all hands on deck event. Jan holding the tail cone, Mike K. installing a Cleco, me working on the bottom skin and Mike T. on the far side of the tail cone.

Total time at the hangar was about 45 minutes much of which was spent devising a plan of attack, rounding up Cleco pliers, clecos and a couple of hole alignment tools. We took our time and the actual mating process didn’t take very long ... perhaps 20 minutes or so. Jan, to her credit, was a real trooper because she had the most taxing job of holding the tail cone the entire time and only started getting tired of holding it as the final few Clecos were being installed. She reports she can feel the burn today.

After getting the RV-12’s tail cone mated to the fuselage, we left the hangar and celebrated the event over lunch and a few effervescent adult beverages. Having worked on the RV-12 until after midnight the night prior, was not too eager to return to the hangar to continue on. So took the rest of the day off and did not feel guilty because major progress was made.

Friday, April 24, 2015

Final Preparations For Tail Cone Mating

Yesterday was a long and busy day at hangar 45 … but productive. The list of items needing completion prior to mating the tail cone with the fuselage was completed.

The final routing of the Tygon tubing for the AOA (angle of attack) sensor was decided upon. There were two tooling holes that grommets were placed into … one in the lower aft edge of a F-1223 baggage rib and the other in the F-1206A bulkhead. This worked out perfectly … when the tubing passes through the grommet in the F-1206A bulkhead it immediately meets up with the wiring harness in the tail cone going to the ADAHRS. This will work out great. The Tygon tubing will be secured to the bottom skin by a dollop of silicone.

Final routing of the Tygon tubing for the AOA sensor in the ADAHRS. This path places the Tygon tubing well below the torque tube for the left flaperon when it gets installed.

Once the Tygon tubing passes through the F-1223 baggage rib it makes an immediate bend aft and passes through the F-1206A bulkhead to join the wiring run to the ADAHRS in the tail cone.

After the AOA routing was finalized, the tail cone was slowly worked closer to the fuselage but canted at an angle so there was still access into the tail cone to work on the wiring and plumbing for the Dynon ADAHRS. The excess pitot and static line was worked forward along with the trim wiring cable and all the wires running to the ADAHRS unit were worked aft through all the loose wire ties. Once all the ADAHRS wiring was pulled aft, the heat shrink tube was shrunk down over the wires and the plastic DB connector shell was screwed together using nonmagnetic brass hardware substituted in place of the steel hardware shipped with the connector. Next the the static air tubing was cut and the “Y” was installed.
Tail cone was worked forward to the fuselage and canted to allow access into tail cone to mount the ADAHRS unit and attach the “Y” for the additional static air tube going to the instrument panel.

The “Y” installed in the static air line so static air can be routed forward to the instrument panel for the backup instruments.

The DB connector was screwed onto the Dynon ADAHRS unit along with the temperature probe connector and then the ADAHRS unit was installed in its mounting fixture on the roof of the tail cone with the supplied nonmagnetic hardware. Note for other builders: … the screws supplied were black so they did not look like brass or anything nonmagnetic at first glance. A magnet was used to verify they were nonmagnetic during kit inventory.

After the ADAHRS unit was secured to the tail cone the pitot and static air line tubing was attached onto the ADAHRS unit using the supplied connectors. These connectors although bulky are really easy to use and really only need to be hand tightened. The instructions say the nut can be tightened further by going 1/4 turn beyond hand tight by wrench if desired … I desired, so that is what was done. Next the Tygon tubing for the AOA port was attached finalizing the instillation of the Dynon ADAHRS unit.
Tightening  the static air and pitot fittings 1/4 turn past hand tight with a wrench completes the instillation of the Dynon ADAHRS unit.

Completed Dynon ADAHRS instillation ... just needs a few wire ties.

The last item that needed completed prior to mating the tail cone to the fuselage is installing the left and right fuselage side skins.
Pealing off the blue protective coating from the right fuselage skin to ready it for riveting after the tail cone is attached.
Left fuselage skin in place and ready for riveting.

It was after midnight when the side skins were finally on the fuselage  so called it a night. The late night push was because friends are going to help with the mating of the tail cone tomorrow so needed to be ready.

Wednesday, April 22, 2015

Preparations For Mating Tail Cone To Fuselage

This work session involved finishing up the bending of the tail cone’s tabs to the prescribed angles and chipping away at the list of tasks remaining to be finished prior to the mating of the tail cone with the fuselage ... which is slated for later this week. Bending the remaining tabs was not hard, but is a little time consuming if striving for near perfection.

Fellow builders following the DOG Aviation Blog know I have gone off the reservation a tad by running the ADAHRS wiring and pitot plumbing prior to mating the tail cone. This was done in the hopes of being able to mount, wire and plumb the ADAHRS unit and install the ADS-B antenna without needing to crawl inside the tail cone to do so. So far it has been working out … but will know in a day or so when attaching the tail cone onto the fuselage if this was all folly or a really good idea.

Once the task of bending the tail cone’s tabs was completed, moved on to installing the ADS-B antenna mounting plate on the bottom skin of the tail cone. The mounting plate was drilled and primed just before winter’s deep freeze gave DOG Aviation the one two punch.  The rivet holes on the antenna doubler plate were cleaned of any primer along with the area around the two mounting holes that secure the antenna onto the tail cone.  Removing the primer from around the antenna’s mounting holes is quite important because the two antenna mounting studs supply the ground to the antenna. The antenna doubler was riveted into position with four rivets and the antenna bolted in place and torqued to 20 inch pounds.
The ADS-B antenna and the antenna mounting doubler plate. To insure good grounding, the primer has been removed from the doubler plate in the area where the antenna will be bolted to the doubler plate.

The next order of business involved spraying some rattle can zinc chromate primer on the tail cone at those locations where the tail cone's skins will be overlapped by fuselage skins. Some of the overlapped areas were already primed correctly with the much better Akzo primer … but the sides downward and bottom were overlooked when they were primed long ago. Unfortunately, priming the areas now became somewhat of a time consuming task because it required completely masking off the tail cone to prevent over-spray. The parts I missed long ago consisted of the forward edges of the F-1282-L&R bottom skins, F-1281-L&R lower skins and F-1280-L&R side skins.
After masking the tail cone to minimize over-spray, the areas of the tail cone that will be overlapped by the fuselage skins were primed with a zinc chromate primer.

While the primer was drying, decided to prepare the Dynon ADAHRS unit for instillation by installing the fittings for the static air, pitot and AOA lines. Because of not being sure if thread sealers would affect the nylon fittings over time, opted to use Teflon tape on the threads of these fittings.
The Dynon ADAHRS unit with fittings installed and ready to be bolted in place in the tail cone.

Because the DOG Aviation RV-12 will have backup steam gauge instruments requiring a static air source, it will be necessary to tap into the static air line prior to the ADAHRS unit. The DOG Aviation procurement department found a neat “Y” fitting at Stein Air for the nylon static air tubing. The static lines just slip into the fitting and lock in place … the fitting does not require any tools. Each port has a ring that can be pulled back to release the tubing should that ever become necessary.
This “Y” fitting will tap into the static air supply so an additional static air line can supply static air to the instrument panel for the back up instruments. The "Y" will be inserted in the static air source just ahead of the ADAHRS unit.

Ran out of time so will install the "Y" and Dynon ADAHRS unit during the next work session.

Monday, April 20, 2015

Bending Tabs On The Tail Cone Assembly

In preparation for mating the tail cone assembly to the fuselage felt now is a good time to bend the tail cone's tabs per the plans. Much the same as the closeout for the wings, the tabs on the tail cone assembly that will mate to the fuselage assembly require bending to various angles. Depending on the location of the tab, the plans have the builder bending the tabs 10, 9, 8, 7, 6 or 3 degrees.

The original plan was to use the digital level to establish the angles … but it was quickly realized that due to the flexi nature of the mouth of the tail cone that was not going to be a good option. Finally settled on using the digital level to mark the required angles onto a piece of cardboard, and then carefully cut out the pieces from the cardboard to use as a gauge.
Pieces of cardboard cut to be used as angle gauges for bending the tabs on the tail cone per the plans.

Technical difficulties: This paragraph will only apply to those who have dimpled the tail cone for flush rivets. The plans suggest bending the tabs on the tail cone using the same bending tool fabricated for bending the closeout for the wings. This tool will not work on the DOG Aviation RV-12 because the rivet holes in the tabs have already been dimpled for flush rivets. During the winter I gave this issue some thought and came up with what seems like an easy and eloquent solution to the problem. Another bending tool was fabricated with a much wider slot. A thick piece of aluminum flat bar 3/4" wide was cut and a hole carefully drilled and machine countersunk to create a spacer. The location of the countersink is such that when the spacer is placed under the dimples on the tail cone’s tabs, the spacer sits flush with the outer edge of the tabs. The slot cut into the bending tool is the same 9/16" depth as the original bending tool however the throat is opened up so when the metal spacer with the countersink is sitting under a dimple, the tool barely slides over the tabs on the tail cone. This worked out great for bending the tabs … so for those that have dimpled for flush rivets this is a viable option for bending the tabs on the tail cone.
Modified bending tool with a mouth just wide enough to accommodate the thickness of the tail cone tab and the countersunk bar stock spacer.

Using the modified bending tool is easy … just place bar stock spacer under the dimple in the tab. This creates a flat surface for the bending tool to work with. Next slide the bending tool over the tab and spacer then begin bending to the desired angle. Zooming in on the photo below one can see the countersunk spacer under the tab being bent.
Using the modified bending tool with countersunk bar stock spacer to bend one of the tail cones tabs.

By the time the modified bending tool and spacer was fabricated, didn’t quite have enough time to finish bending all the tabs … so will finish up that task during the next work session.

Sunday, April 19, 2015

Service Bulletin 14-12-06 Finally Completed

The weather cooperated nicely Friday … the early morning rains gave way to what I believe may have been the first 70 degree day of the year. Taking advantage of the late afternoon warmth and favorable breezes, a small batch of Akzo primer was mixed up and sprayed onto the new replacement pieces for the bearing bracket brace using the air brush. The wet parts were placed into the heated paint drying box and allowed to dry all day Saturday.

Today the freshly primed F-1206F-1 bearing bracket and F-1206J-L&R angles were secured together with Clecos per the plans and riveted together. A small change was made to the Van’s supplied AN470AD4-4 rivets. Those rivets looked a little short to me ... a quick measurement using a rivet gauge verified my suspicion so a slightly longer AN470AD4-4.5 rivet was used to secure the pieces together.
The rivet gauge shows that the increased length of the AN470AD4-4.5 rivet is the perfect length for this location.
Riveting the F-1206F-1 bearing bracket brace onto the F-1206J angles using AN470AD4-4.5 rivets in place of AN470AD4-4 rivets.

Completed new bearing bracket brace assembly ready to install in the fuselage.

Once the bearing bracket brace assembly was riveted together, it was time to install it in the fuselage. Wow! This is a tight fit. The ribs to the left and right require flexing a little to allow the bearing brace assembly to slide into position. Another testament to Van’s quality control … once in position, the new assembly fit perfectly once all the holes were properly aligned. Riveting the assembly was uneventful and only took a small amount of time.
Riveting the bearing bracket in position using the supplied AD4-6 rivets.
Completed installation of the new improved bearing brace assembly which completes service bulletin 14-12-06.