Today I visited my friend Mike who is also building an RV-14. Mike is about a year ahead of me, and is about to mount his engine. It was great to see his plane on it’s gear, and to look at how Mike did things.
I borrowed a rotisserie that Mike had finished using, which will be helpful in the near future.
Tonight I worked on cleaning up the wiring around the autopilot servo. Following Mike’s example, I drilled and stepped up a new systems hole that allows me to route the wiring in a more direct path.
I couldn’t finish that job as I’m waiting on some longer AN3 bolts, and some Adel clamps.
Next I worked on the aileron pushrods. Using some spare nuts, I installed the rod end fittings in the drill press and sanding them down slightly until they fit snugly in the steel tubing. Then I drilled and primed the tubes. I only did this one one, as I’m waiting on replacement parts for the other one.
Wiring in it’s original location. I am moving the servo wiring down close to the spar. Will do an “after” photo later
Pushrod with end fittings temporarily attached.
Post-script… I did receive the bolts and re-routed the wiring, the result was a much cleaner install and wiring routing.
Servo wires are now routed along the spar, and secured with an adel clamp. There is a service loop to the left, just out of the picture. This is a much better setup.
The last two days I spent time making some mount brackets for extra molex connectors in the wing root. I needed to have at least some modifications to account for the pitot heater wiring (3 wires), but wanted to also mount a molex connector for the extra wiring I’ve run through the wings. This will make it much easier to install additional electrical devices in the wings later.
After checking with Vans, that I could safely rivet through the torque tube mount bracket, I cut out some small plates from a sheet of 1/16 aluminum. Then I marked the location for the molex connectors, cut them out with a drill and Dremel tool. Once I had a good fit for the molex connectors, I located them, drilled some holes, deburred, primed and riveted the plates into position. I have one connector on the right wing for the three spare wires, and two connectors on the left wing; one for the pitot tube wiring and one for the spare wiring. I used a bigger molex connector for the pitot tube wiring since this will carry 10A on two of the wires (power and ground for the heating element). The spare wiring will carry much lighter loads, as the wire is a smaller gauge.
One of the plates I’m using to mount the extra wiring molex connectorsCutting holes to size with the Dremel toolCutting holes to size with the Dremel toolRight wing test fitLeft wing plate primed and rivetedLeft wing completedRight wing completed
Today I spent some time tidying up and securing the wiring runs in the wings. This was mostly a case of installing zip ties and de-slacking the runs. I also installed some heat shrink to each of the molex connectors and installed some spiral wrap in areas where there’s a possibility of rubbing on bolts on the wing spar, or screws from inspection plates etc.
Zip ties on wiring runsHeat shrink where wiring runs terminate into molex connectors
The last month has been busy, and I wasn’t able to make much progress on the airplane. Yesterday and today I worked on the pitot tube mount install, and a couple of other odd jobs.
I enlarged a set of systems holes in the left wing ribs so I could run a pitot and static line from the wing root to the ADAHRS, that will be installed in the left wing (two of them actually).
Hole circled in red can be enlarged up to 5/8ths. Since I’m installing the ADAHARs in the wing, I need to run a static line out there.Hole enlarged and static line inserted.
I decided to replace the pitot mount plate that came with the Gretz mount, because it needed more joggle, but was already dimples which would interfere with the joggling process. A secondary issue was that it wasn’t really wide enough for the 14, due to the rivet spacing on the wing spar.
Bottom left is the Gretz supplied plate. Top left is the new plate I made, and on the right is the joggling device. The sheet to be joggled is inserted into the slot and laid flat. Then the sheet and joggle device are squeezed in a vice. The result was a nice crisp joggle
I ended up making two, because the first wasn’t quite wide enough, but it was easy enough to cut out on the bandsaw, mark, drill, joggle, cut out the hole for the pitot mast, and then dimple. I had to make a tool for joggling, based on an idea from EAA Hints for Homebuilders. It came out perfectly, and it’s going to be great.
I installed a piece of angle onto the appropriate rib, then fitted the bottom skin and then match-drilled holes into the skin from inside. This necessitated a new drill, so I picked up an electric angle drill from harbor freight. It worked great until the battery ran out, and I realized I didn’t have a battery charger for this brand. So annoying! I will try to get one tomorrow.
Angle being fitted to the ribAngle installed on the ribAngle drill to match drill into the skin from inside the wingPart way through the match drilling process
Then I switched to another job, drilling, tapping and countersinking the pitot mast, prior to powder coating. The mast is steel, so countersinking takes a bit longer, but it’s also easier to control. The hard part is countersinking the curved leading edge of the mast. I ended up free-handing this, as I found I could see a little easier than if I had used the caged countersink. The end result was ok; not perfect, but good enough… I doubt I’ll spend much time looking at the pitot tube!
Drilled and tapped screw holes for fastening the pitot mast to pitot tubeCountersink screws
I mounted the pitot heat controller onto an access panel. This will be the mid wing access panel, just inboard of the pitot tube. This was simple enough, just center in the panel, drill holes, countersink, install screws. I did run into some problems with cracks forming on the dimples on the large #8, and even #6 holes.
Drilling and upsizing holes for the controller unitDimpling the plate with the DRDT-2 dimpler
The first crack showed up while dimpling the mount holes using my #8 dies. A warning in the plans calls out the risk of cracks when dimpling large holes. This is compounded by the fact that the wing skin (and access panels) are about as think as you can dimple. All the stress of the dimpling process will crack any stress risers, so I found out.
This dimple cracked because I didn’t remove some scratches near the edge of the hole. When I was drilling the holes, some metal chips were trapped between layers and scratched the skin. I used scotch bright to remove them, but didn’t completely smooth out the scratches. This seems to have caused the crack on this hole. I set this panel aside and rebuilt using another (I have several in the kit). In the new panel I went ahead and drilled and dimpled all the holes, just in case I ran into another crack issue… which I did on the last hole. This hole was a #6 screw hole, and I guess I had an imperfection somewhere. The crack was not all the way through so I tried filing it out. This worked ok, so I decided to keep this panel.
Cracked dimple on a #8 screw hole.
I made some spacers to allow the skin dimples to nest without countersinking the controller box.
Countersunk spacers
I tested the install with some screws and nylock nuts on hold it in place.
Final setup of pitot heat controller unit
Then I primed the parts with some rattle can primer, put some locktight on, torqued it up and put some thread lock on.
Tonight I spent time redoing some wiring on the left wing. The main task was widening the holes in the ribs, allowing more wires to pass through for the heated pitot tube, plus some spare wires.
I picked up a 5 foot drill bit extension from Amazon for a few dollars. I installed my step drill bit which has a max size of 1/2 inch, my target hole size. The first problem was the fitting on the extension, which was significantly wider than 1/2 inch. I spent time grinding this down to just a hair under 1/2 inch.
Modified drill extension. This was ground down to fit through a 1/2 inch hole
With that done, I pulled out the wiring runs from the holes in question. I decided to unpin the molex connector for the main harness, because I’m going to replace this with a 12 circuit connector. This will allow me to terminate the pitot wires along with the lights etc. I found a wiring diagram another builder used, and will borrow that same layout. Anyway, I pulled out the wiring and then popped out the snap bushings, and started stepping up the holes.
I’m only going to up-size the system holes for the wiring runs, the two “spare” sets of holes will be occupied by my two pneumatic tubes for pitot and AOA. I could probably squeeze some more wires in with the tubes, but that’s not the plan.
The extension worked quite well, and I was able to quickly drill through all the ribs. The only issue came with the very last one, the most inboard that I needed to drill, because the drill extension was 6 inches too short. I was drilling from the inboard end, and had anticipated this, so I had another 12 inch extension. All was well until the smaller extension started slipping, and quickly reamed itself out. Luckily the step drill was almost through the hole, and some quick filing enlarged the hole enough for the snap bushing.
Drill extension extending through the ribs that have been drilled. I was trying to fix my smaller extension here while drilling the final rib.
Some deburring, installing larger snap bushings, and then I re-ran the wiring.
This shouldn’t have taken long, but the tool modifications took longer than I had hoped. It was late by the time I finished, so that’s all I got done tonight.
Step drill almost through the last of the ribs. Beyond this rib, only a subset of wires need to continue out to the end of the wing, so I don’t need to increase the hole diameters from here out. The left hand bay in this pic is where the pitot heat controller will mount, terminating several larger gauge wires.
I spent a couple of hours running wires in the left wing tonight. It wasn’t much work, but the experimenting/thinking/researching took time. I decided where to place the pitot tube, the pitot controller, and looked at a few different blogs to get some inspiration. Sadly, by the time I finished the wiring, I had already decided I’m going to rip it all out again and change a couple of things.
Running the lighting wiring harness in the left wing
I ran the left hand wiring harnesses per the plans. There are three sets of holes in the ribs, two are big enough for my pneumatic hoses for the pitot and AOA, one per hole. That leaves just one set of holes for all the wiring. This might be ok if you are just installing the regular wiring harnesses, but I’m planning to run some twisted pair wire for the pitot heater, plus several spare wires, and there’s no way that will all fit in the relatively small sized holes. I found a Vans article that describes options, and I decided to step out the wiring holes to half inch, which should solve the problem.
Today I ran wiring for the right wing. I found that I had plenty of space for the standard wiring harnesses, plus several spare 18 and 22 gauge wires that I ran for future use. The wiring runs were for the AutoPilot, Trim Servo, and the wing lighting.
I have a label printer that will print on heat shrink, so I can easily label wires. This makes it so easy!
An example of a printed heat shrink label. Slip this over the wire, hit with heat-gun for a few seconds and the label is done
Many builders run conduit through the wings, to make it easier to run cable in the future. At this stage my plan is to just install several spare wires for future use, and not install conduit. Conduit would require drilling a new set of holes through each rib. It’s not really necessary, as I can reach each rib via the access panels anyway.
First wiring to go in was the autopilot servo harness. Wiring runs through the inboard ribs of the right wing. Opening in the background is where the aileron trim will mount.At the wing root, the wiring harnesses terminate in these molex connectors. I will probably install so heat shrink here in the future as a strain relief for the bundle.Wingtip lighting harness installed on right wing
