Pitot/AOA – RV-14 Build

Assembly Tasks

Posted on November 21, 2025 by Neal

This week I made multiple trips to the hangar to work on various tasks.

Wing attach bolts

I finally torqued the wing attach bolts. The night before, I tested out my torque wrenches to ensure they were reading correctly, and they were both very close. I used a vice to hold the wrench, and then secured a weight over the arm and measured the distance from the fulcrum. For weight I used a 1 Gallon plastic jug filled with carefully measured amounts of water. The nuts were easy to torque, I only found one where it took a second to figure out how to torque it. I ended up using a socket extension that allowed some movement, so I could torque the nut without fear of bending small bits of aluminum that were close by.

Pitot tube:

I finalized the wiring and install of the pitot tube. I used butt splices to connect the pitot heat wiring, replacing the original molex connector. In the process I included a service loop to help with any future maintenance.

I also trimmed the pitot and AOA pneumatic lines at the wing root, inserting them both into the connectors under the seat. I still need to test the system for leaks, and to verify I didn’t switch Pitot and AOA at any point in the system.

Strobe lights:

I did some troubleshooting on an issue with the wing tip strobe lighting. Both sets of strobes are flashing, but weakly. There is only 6.6V at the wingtip, so I’m losing half the voltage somewhere in the system. I tried the easy tasks such as unplugging and reconnecting connectors, but no luck.

VOR Antenna

I completed the VOR antenna wiring, and was happy to tune in a nearby VOR and see a positive ID and a needle on the CDI. The reception seemed good, even though the antenna isn’t well grounded (I don’t have all the screws in the wingtip, and they provide the ground path). The job was quite simple, I just needed to cut the cable to length and install a BNC connector, then plug it into the fitting I had previously installed under the passenger seat. I added a service loop, for ease of maintenance. At the right wingtip I connected the ring terminals to the antenna and torqued them up. I also tidied up the wing tip wiring and then secured the wingtip fairing. I then fired up the instrument panel, turned in the Julian VOR and was happy to see the reception, even on the ground in a metal hangar at 20 miles, and without a properly grounded antenna.

The main spar wing attach bolts, final torqued

Signs of life from the VOR antenna. The Nav radio is tuned to 113.75, and the green line on the left hand screen (PFD) is pointing to the VOR station

The VOR antenna connection under the passenger seat

Right wingtip wiring. With the wingtip off, I found I could rotate it and set it on its aft edge, balanced against the wing. This made working on the wiring much easier.

Service loop for the pitot heater wiring. Insulated butt splices are visible here and would be the recommended place to disconnect the pitot wiring for any maintenance

Another angle of the pitot tube install. Note, the pushrod is disconnected to allow more room to access the pitot tube wiring.

Pitot wiring

Posted on April 29, 2025May 3, 2025 by Neal

Tonight I finalized the pitot wiring. I have a separate connector at the wing root for pitot heat. Since I had previously planned for a regulated pitot tube, I had three wires run to the pitot tube. With the unregulated model, I don’t need to use the third wire, so I’m leaving it in place as another spare wire.

I unpinned the pitot heat wire from the standard Vans wiring harness and connected it to the separate Pitot heat molex connector, then ran another ground wire from the pitot heat molex connector to the ground point on the fuselage. At the pitot tube end, I installed pins on the wires from the pitot tube, but held off on installing them into the molex connector. I need to wait until I have installed the mast, and the pitot tube, routing the wires through the mast in the process. If I install the connector now, there won’t be enough room to fit the molex connector through the mast.

Anyway, it was a fairly quick job to get this all finalized.

The four connectors at the wing root are a little overkill. The two on the left are standard Vans wiring harness. The third from left is the pitot heat connector, and the right hand connector connects spare wiring that runs to the wingtip.

This is where the pitot mast will attach. The wiring will plug into the molex connector on the right. The Pitot and AOA lines will attach to the white and blue lines respectively.

Feeling pretty good about progress so far.

I went ahead and retrieved the bottom wing skin from storage. This has some history, having been partially attached to a different left wing earlier in the build. I was very careful when I removed it from the original wing, and it’s in great shape.

Pitot tube

Posted on April 28, 2025May 3, 2025 by Neal

Tonight I bent, flared, and fit the Garmin pitot tube. Doing this for the second time (first time was Dynon) was a lot faster, and easier because I could use the Dynon tube bends as a reference.

There are some interesting differences in the Dynon and Garmin pitot tubes. The Dynon is noticeably longer. The tubes are marked “pitot” and “AOA” on the Dynon, but unmarked on the Garmin. I added some heatshrink labels to identify the tubes, after gently blowing through them to confirm which was which.

I’m installing the unregulated Garmin pitot tube, so there’s no controller box needed. The switch on the panel will turn it on, and it’ll stay on until switched off on the panel. This is how it works on most aircraft, and since I’ll hardly ever use it, simple seems best.

Tubes need to be bent to allow clearance from the aileron pushrod, without contacting the spar

Some thought was required to remember to put the b-nuts on at the right time: after the tube is bent, before the tubes are flared.

Pitot Mast

Posted on April 27, 2025May 3, 2025 by Neal

I’ve decided to switch back to working on the wings, so I can finish them up and then move them to a hangar. That should give me a little more room in the garage to finish the tail fairing.

It has been a couple of years since I worked on the wings, and a bit of a saga. My original quick build wings were impacted by the Vans primer problem, and I sent them back. But I had already made up the bottom skin for the left wing, including a cutout and holes for pitot mast and reinforcing. I had started riveting the skin on when the vans primer problem was announced. I carefully removed the rivets, and saved the skin. Then I decided to switch from Dynon to Garmin, which meant a new pitot tube. Unfortunately the hole pattern is slightly different and the screws are different sizes between the two. Since the Gretz pitot mast I have is no longer available for sale, I wanted to keep the original mast and bottom skin, and find a way to make it work.

On closer inspection, the holes are in almost exactly the same place. The different is the screw diameter, with Dynon using something like a 3/16 and Garmin a smaller #6-32 screw.

Because the screws carry a sheer load, and because there is plenty of material supporting the screw, I decided to use something JB Weld to fill the void under the screw heads. I coated the pitot tube mount and the screws in boe-lube and then set them into the filler. In the morning the filler had dried, and I backed the screws out, then cleaned up the filler with a file and some sand paper. I painted the filled area with some powder-coat touch up paint. The finish looks rough, but I’ll worry about it when I paint the plane, eventually.

Pitot static lines

Posted on April 18, 2024 by Neal

Tonight I started on the task of running pitot static lines from the wing attach point to the panel. There are two lines that run in from the wing, a pitot line and an AOA line. They will t-off behind the panel with one line going into the back of the AHARS, which is mounted to the back of the PFD, and the other lines running to the G5 backup instrument.

This ribs already have one set of holes running through the seat ribs that is just the right soze for one line. There are other holes too, the outboard ribs have two additional holes for installing gear leg bolts for tri-gear models. The inboard ribs have tooling holes. I enlarged one of three tooling holes on each of three two ribs under the pilot seat, and installed snap bushings. Conveniently, the spar already has two holes I can use to run these lines forward of the spar and into the center tunnel.

I’m planning to install quick connect fittings somewhere under the pilot seat, probably on one of the inboard ribs. I ordered a few fittings from Stein Air and will tackle that when they arrive.

Shavings visible for enlarging the top hole. The angle of the camera makes it look like these holes are closely spaced, but there’s over an inch edge distance.

After using the step drill to enlarge one of the tooling holes. I actually drilled a new hole to offset the center of the enlarged hole, ensuring enough clearance

Pitot tubing

Posted on April 22, 2022May 28, 2022 by Neal

Today I match drilled the pitot tube brace to the rib, and then riveted it in place on the rib. Now it’s ready for the bottom skin install. Then I installed an adel clamp to hold the pitot lines near where they will connect to the pitot tube, and torqued the bolt.