Left Wing Lower Inboard Skin Prepped For Riveting

The covering of the RV-12’s left wing skeleton begins by turning the spar/skeleton assembly upside down and positioning the W-1201-L lower inboard skin onto the wing skeleton. After the skin was gingerly set into position, the blue protective film along the rivet lines needed to be removed with a soldering iron prior to riveting.

                                       Jan helping to set the W-1201-L lower inboard wing skin into position.

                                              Using a soldering to melt peal lines into the blue protective film.
                                              This makes removing the blue film from the rivet lines a snap.

After the rivet lines were cleared of blue film, the skin is secured onto the wing skeleton with lots and lots of Clecos. My hands were starting to get cold so did not totally finish securing the skin onto the skeleton so there will be a little more Cleco work before riveting begins.

                                          Using Clecos to Secure the W-1201-L lower inboard skin onto the left
                                          wing skeleton. The Clecos will hold the skin in place during riveting.

Preparing Landing Light Ribs & Lens Backing Strips

The afternoon was spent preparing the landing light mounting ribs for both wings along with the lens backing strips. The landing light ribs require a doubler plate to give them some rigidity in the area where the light mounts. AN426AD3-4 flush rivets are used secure the doubler plates onto the landing light ribs. The doubler plates were machine countersunk prior to priming, so they were ready to rivet onto the landing light ribs.

                              Using the pneumatic squeezer to secure one of the doubler plates onto a landing light rib.

                         Front and back views of the landing light ribs after the doubler plates were riveted in place.

The plans would have the builder drill mounting holes into the Plexiglass lens along with trimming the lens at this point. However, from everything I’ve read, it should not be attempted if the Plexiglass is below 70 degrees. Guess I will need to wait until spring thaw to finish that aspect of the landing light install.

While the pneumatic squeezer was in use, decided to finish up the preparations for the lens backing strips used to secure each landing light’s lens onto the W1203L&R wing skins. The backing strips receive K1000-06 nut plates which require dimpling because the rivets used for mounting the nutplates are flush rivets. The reason for this is the backing strip compresses the Plexiglass lens onto the wing skin to keep it secure, therefore the backing strips need to be smooth so they won’t crack the lens. The backing strip rivet holes were dimpled prior to priming as were the nutplates … so once again it was easy to just rivet the previously prepared components together.

                                             Using a pneumatic squeezer to rivet a K1000-06 nutplate onto one
                                             of the lens backing strips with AN426AD3-3.5 rivets.

                                Completed lens backing strips for both landing lights … ready for final assembly.

The rivet holes in the W1203L skin for mounting landing light ribs have not been drilled yet. I wanted to see if it was possible to insure a really perfect fit for the landing light ribs between the top and bottom of the W1203L wing skin … so I experimented a little. I temporally mounted the landing light onto the landing light ribs and tried to position the assembly perfectly behind the leading edge. That idea turned out to be pure folly because it was almost impossible to hold the light assembly in position just to look at it, yet alone drill. Even if I had another pair of hands, I don’t think my small 90degree drill would have been usable in the cramped quarters. Guess I will have to use the template with blind faith and hope for the best.

Left Wing Landing Light Cutout Completed

After waiting most of the day for the temperature to get UP to freezing decided it was time to make the long overdue landing light cutout on the leading edge of the W-1203L wing skin. As I was about to head out to the shop, my friend Bernie swung by to check out the project … perfect timing, the extra hands for this operation proved useful and were greatly appreciated.

Admittedly, carving up the leading edge of the wing skin with a power tool is a little disconcerting. The instructions have the builder trace the top half of the cutout along with marking locations where holes will be drilled on the upper surface of the skin then repeat the process for the bottom portion of the wing skin all the while using six designated rivet holes as alignment points.

After the cutout for the landing light was traced onto the W-1203L wing skin, a step drill was used to drill access holes for the jig saw. Next the skin was flipped over so the leading edge hung down from the bench and the bottom portion of the cutout was cut with a jig saw.

                    Using the jig saw with a 24 teeth per inch blade to cut the bottom half the landing light hole.

                            Bernie preventing the skin from bouncing while holding a light so the hole marks could
                            be clearly seen as the lower portion of the cutout is rough cut with the jig saw.

Once the bottom half of the hole was successfully cut, the W-1203L skin was flipped over and the upper half of the hole was cut while Bernie held the light and put pressure on “curve” to help keep the skin tensioned.  This part was a little dicey and it was hard to keep the jig saw moving smoothly but fortunately all went well.

When the time comes for cutting the right wing’s landing light hole, think I will try another method of cutting the top portion of the hole. After the bottom cut is made I’ll Cleco the skin onto three ribs to secure the skin while the jig saw makes the cut. I feel this will be a better option as opposed to having the skin flopping around like it was beginning to do. While smoothing the cut with a Dremel tool, I did Cleco the skin onto three ribs and that really worked nicely to keep the skin in place.

                                             Using a Dremel outfitted with a sanding drum to smooth the edges.
                                            The sanding drum did a great job of quickly fine tuning the material.

                                                 Finished landing light hole in W-1203L wing skin after using
                                                 the Dremel sanding drum followed by the ScotchBrite wheel.

To finish the landing light cutout, four holes need to be drilled into the W-1203L skin where the center punch marks are above and below the cutout. These marks can be seen in the above photo. The eight holes will be used for the lens backing strips which will secure the Plexiglass lens snug to the skin.

Cutting Holes For Left Wing Lighting Begins

Because of the cold weather, I’ve spent plenty of time inside the house pondering the best way to go about cutting the necessary holes in the left wing’s skins for the landing light and navigation/strobe lighting. Because the RV-12 lighting kit instructions supplied by Vans are geared towards those RV-12 owners who already have the wings built, there is not a step by step procedure covering the “best” way to install the lighting kit during wing construction.

Braving the cold in the shop, decided to start by making the necessary cuts while the skins are not riveted in place ... if there is a hint of an issue, I’ll stop and move forward constructing the wing and then make the cuts. The access hole cut into the W-1204D skin will be easy because it is a flat skin.  …. however, I’m more than a little concerned about the cut in the leading edge of the W-1203-L skin where the landing light installs. Because of the curved nature of the leading edge, making the cut on the finished wing has some advantages as does making the cuts while the skin is on the bench. Both methods have a few cons as well.

In order to refine the cutting method, the W-1204D skin was cut first because that hole will be covered by a fiberglass faring. The inverted drawing I had printed up earlier worked great for marking the hole placement. A flashlight was used under the skin to illuminate the rivet holes from below while the template was adjusted until all the template rivet holes were properly positioned with the skin and then the cutout was traced onto the skin. The plans also have measurements which were also verified just to be sure. After the cutout was traced onto the skin, a step drill was used to make a couple of holes for jig saw access. Originally a cutoff wheel was the tool of choice but I thought better of it and settled on using a variable speed jig saw with a fine tooth saw blade of 24 teeth per inch. I was apprehensive about using a blade with less teeth per inch for fear of having the blade catch on the skin and creating dents. A layer of duct tape was placed on the bottom of the jig saw so the primer would not get scratched by the saw’s base.

                          Cutting the navigation/strobe wiring access hole into the W-1204D-L skin using a jig saw.

 The jig saw worked well, all things considered, and did not catch on the skin so will try that method on the leading edge cutout. After the hole was cut, files were used to smooth the edges, followed by a 1” scotch-brite wheel, a little hand sanding and the drilling of a #19 hole for a ground point.

                         Hole on the left is the completed wiring access hole in the W-1204D-L outboard wing skin.

Left Wing Electrical Connector Completed

The two shielded cables being used for the navigation/strobe and landing lights were prepared by stripping off about 3 inches or so of the Tefzel insulation leaving the shield intact. The shielding was then loosened by pushing up on it so the three internal wires could be fished out through the shield at the point where the outer insulation was stripped away. The shielding is then pulled back and a heat shrink tube is used to identify and dress the end of cables.

                    Shielded cables fully prepared and labeled … ready for heat shrink to be placed over the shield wires.

                                    Using the heat gun to secure heat shrink over the cable’s shield wires.

In an effort to create consistency for wiring the additional left landing light, the choice was made to use the same wiring pins on the left wing’s electrical connector as called for wiring the right wing’s landing light. In addition to the steady on and pulse power, wig wag operation requires an additional wire to be run from the master output of one light to the slave input of the other light (think wig wag sync). Because a single right light is the typical instillation, the decision was made to establish that light as the master and wire the left light as the slave. Pin 3 was available on both wing’s electrical connectors, so it was chosen to connect the wire that needs to run from the right landing light’s master output to the slave input on the left light for wig wag operation. Bellow are the pin assignments that will be used for wiring the eight pin Amp connectors on both wings.

Left Wing Amp Connector                         Right Wing Amp Connector

Pin 1      Ground                                       Pin 1     Ground
Pin 2      Stall warning indicator                  Pin 2      Not used
Pin 3      Right master out to left slave in     Pin 3      Right master out to left slave in
Pin 4      Landing light power                      Pin 4      Landing light power
Pin 5      Wig wag power                            Pin 5      Wig wag power
Pin 6      Navigation light power                   Pin 6      Navigation light power
Pin 7      Strobe light sync                          Pin 7      Strobe light sync
Pin 8      Strobe light power                      Pin 8      Strobe light power

Once a wiring plan was made, the drawings were updated to reflect the additional wiring in the left wing. Connector assembly began by crimping pins onto the ends of all the wires using a ratcheting crimping tool with dies for open barrel connectors.

                                         Using the ratcheting crimping tool with dies for open barrel connectors
                                          to crimp the connector pins onto the ends of the wires.

           Left wing’s electrical connector with all wires in place ready to be secured onto the mounting standoffs.

                                                  Left wing’s electrical connector mounted onto the standoffs.

Still need to place small wire ties on the connector’s wires to give them more security. Unfortunately the wire ties in stock here were far larger than ideal, so a trip was made to Radio Shack to procure smaller ties for instillation later today. As for grounding, both cable’s shield wires will be brought together and crimped into a ring connector that will be grounded at the same point where the left wing electrical connector’s ground wire attaches … a nutplate. Grounding point is the screw hole with rivets on either side which can be seen in the bottom left of the above photo. To insure a good airframe ground ,the primer will be removed where the grounding hardware meets the rib’s web.

DOG Aviation Receives Technical Councilor Evaluation

The Experimental Aircraft Association, of which I have been a long time member, strives to be proactive when safety is concerned.  The EAA offers its members a technical councilor program which is intended to improve the safety of amateur built aircraft. The idea is for builders to reach out and request their airplanes be inspected during various stages of construction by fellow EAA members who are, in many cases, aircraft matinance professionals.

Last week after a couple of unsuccessful attempts to contact a local EAA technical councilor, the search was expanded and I was finally able to contact a councilor and set up an inspection date. The inspection by Jim Strock, an EAA technical councilor who is a certified airframe and powerplant mechanic, was slated for late Wednesday morning at the DOG Aviation production facility. Being excited about inspecting an RV-12, Jim invited long time friend and fellow EAA technical councilor Don Gray, a counselor experienced in metal aircraft, to join him for the on site inspection.

Both Jim and Don spent a couple of hours asking construction questions, looking over the RV-12’s plans and inspecting the left wing currently being assembled as well as the finished tail cone. They also asked questions regarding construction techniques being used and verified that the proper tools and dies were utilized for countersinking and dimpling based on the type of rivets being used to assemble the RV-12.

Proud to report, both Jim and Don were favorably impressed with the quality of workmanship thus far ... both said to stay the course and keep up with all the good work.

Crimping Wiring Connectors, Progress Sort Of

With the weather outside being dreadful, (cold and lightly snowing the entire day), decided to move forward and crimp electrical connectors on all the lighting units. Was eager to try the recently procured Tool Aid 18937 dies made for smaller sized open barrel connector pins such as the .063” Molex pins AeroLEDs supplies with their LED lights. The 18937 dies did a great job on the “connector to wire crimp” and an acceptable but not perfect crimp on the strain relief crimp on the wire’s insulation ... so those crimps were tweaked slightly using another hand crimping tool I had.

                                   Staying warm inside while crimping connectors onto the landing light wires.

  Close up of the wire crimp created by the 18937 dies. I used a separate hand tool to tweak the strain relief crimp.

                                                                      A finished landing light connector.

Of note: Van’s plans has the builder place the wing’s wires into the male Molex connector for the landing light in no particular order then instructs the builder match wire for wire when placing the landing light’s wires into the light’s female Molex connector. This method will work just fine. That said, should the builder download the wiring schematic and expect the pin assignments to match, good luck! Therefore, I decided to assign the same wire/pin designations as denoted in Van’s downloadable wiring schematic. This will make future troubleshooting far easier should that ever be necessary. For those interested, the pin assignments for the landing light’s Molex connectors are as follows. (Since I’m installing two lights, the right landing light will be wired as a master and the left light as slave … a single light instillation will not use the master or slave wires).

Molex Connector     Light wire description and color
Pin 1                        Ground – Black
Pin 2                        Master Output – Green (wire to other light’s slave to sync wig wag)
Pin 3                        Slave Input – Blue  (N/C on master light, slave light receives wire
                                                                from master output here for wig wag operation)
Pin 4                        Wig Wag Power – Yellow  (will pulse a single light instillation)
Pin 5                        Landing Light Power - Red  (Light steady on)

Upon opening the box for the recently purchased landing light for the left wing, there was first a moment of shock and then aggravation … it was not the same light as the one originally shipped in the lighting kit purchased last summer! This newer landing light has four additional LED lights and more extensive heat sinking on the back when compared to the original light.

Front view … landing light on the left is the original light the one on the right is the new landing light just purchased.

                                            Back view … original light is on the left and one can clearly see all the
                                            additional heat sinking on the back of the new light on the right.

A quick visit to the AeroLEDs WEB site reveled at one point they sold an AeroSun 1600 (my original light) and a model called AeroSun Xtreme.  Both models have the same specifications as far as light output and current draw goes. However, the Xtreme light has four more LED’s plus additional heat sinking and was designed for enclosed spaces where there would be less airflow available to cool the light. The AeroLEDs WEB site now only shows the newer 12 LED light as the current product. They have apparently also changed the name of the light to just AeroSun and have apparently dropped the 1600 and Xtreme designations.  My newer landing light box just says AeroSun. I’m assuming they decided to drop the older design for the more heat forgiving newer Xtreme design.

Guess I’ll order another landing light from Van’s and see what shows up … then return the odd light. That way both wings will have the same style of landing light installed. I know, picky picky … but having two different styles of landing lights installed would forever bug me.

Fortunately, both navigation/strobe lights looked the same (except one has a red LED light and one had a green LED light inside). These lights are also shipped with the same style Molex connectors that were used for the landing lights so the same crimping tool was used to crimp connectors onto all the wires.

                                                       Finished connectors on both the navigation/strobe lights.

Much the same as the landing lights, Van’s plans has the builder randomly connect the wing’s wires to the male Molex connector for the nav/strobe lighting. The builder then matches those connections when wiring up the female Molex connector with the wires from the navigation/strobe lights. Here again, the odds of matching the main wiring schematic is slim at best … here again I opted to follow the pin assignments on the schematic for future clarity.

Molex Connector      Light wire description and color
Pin 1                          Ground – Black wire
Pin 2                          Strobe Power – Yellow wire
Pin 3                          Strobe Sync – Green wire
Pin 4                          Navigation Light Power – Red wire