With my new drill bits in hand, I finished up the Aileron Trim bracket tonight.
Last night I bench tested my landing lights and found one of the LEDs wasn’t working. I took the time to check all the other LEDs (Nav, strobe, taxi, and spot-lights), and everything else worked well. Some very bright lights!
I disassembled the landing lights and contacted Paul at FlyLEDs for some help.
Last night I primed a few small parts and tonight I assembled the Alieron Trim bracket. Once again I was stuck when I realized I didn’t have the right size drill bits to finish the job. I finally pulled the trigger on a set of 1-60 drill bits so I shouldn’t have this problem again.
I’ve been struggling to make much progress recently, as I keep running into decisions that require research, and often ordering new parts and/or tools. Tonight I started on the Aileron Trim servo mount, as this arrived recently from Vans.
Tonight I worked on the “Combo” landing lights from FlyLED. The lighting arrived in a box from Australia, and it was fun to unpack and explore the parts.
The Combo lights are installed in the landing light coves on the leading edges of the wings. These are designed for tail-wheel aircraft, with a cluster of 4 lights, one of which can be angled down, wired separately, and comes with a diffuser cap, to serve as a taxi light.
The largest and heaviest part of the lights are the heat sinks, which are attached to the boards with a couple of small screws and some thermal paste.
The LEDs themselves are very small, but the lenses are larger. The lenses focus and concentrate the light into beams.
Once my bench power supply arrives, I can test these out to see how bright they are.
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!
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.
Tonight I installed most of the fittings into the fuel tanks. The only fitting I didn’t install was the drain on the left tank. Since that wing is sitting on the bench, and the drain port is on the bottom, I’ll wait until I put it back in the stand to install.
I spent time researching exactly how much torque these fittings need, and how to apply the sealant. Couple of useful videos on the EAA website, and more specific info on Vans Airforce. These (like all fuel fittings) are NTP, tapered threads. Torque values are not really applicable, since the jamming of the threads is what provides the seal. It’s not a complete seal, since there is a spiral pathway that fuel could flow out of the fitting, so some sealant is required. Over-torquing will damage the threads, since these are aluminum fittings and relatively soft. Vans recommend installing by tightening until the first sign of resistance is encountered, then turning 1.5-2 turns beyond. The sealant recommended by both the EAA and Vans Airforce members is called EZTurn, which is a sticky, but workable fuel-resistant sealer. Tape is not recommended, due to the risk of contamination of the fuel system with chunks of tape. For the same reason, any sealant should not be applied to the first 2-3 threads on fuel fittings.
I started by cleaning out the fitting ports, using some rubbing alcohol on a lint-free rag. Despite taping over these ports, there was a surprising amount of dirt in the threads. Then I cleaned the fitting threads and applied a coating of sealant, skipping the first 2-3 threads.
I got all of the fittings in, except the left tank drain port, which I can quickly add once the wing is in the stand. I’m going to keep it on the bench until my landing lights arrive on Thursday, so I can fit them. The last step in the tank work is testing for leaks, which I will tackle next weekend once the proseal has fully cured.
I’ve been waiting on some more tank sealer so I could install the fuel senders. UPS claimed they delivered it on Wednesday, but it didn’t show up. On Thursday it turned up with another package, so I was able to install the senders tonight.
I took time doing prep work; scuffing the surfaces, cleaning the surfaces, checking that my multi-meter was working, checking that the screws installed in the nutplates, checking that I had the right size Allen Key, etc. Finally I was ready to mix the sealant and get started.
I had one wing on the bench and one in the stand. The wing in the stand was in a slightly awkward position, as the stand itself was interfering with the placing of the sender into the hole in the end of the tank. With a bit of adjustment I got it to work ok, and that’s the wing I started with. In hindsight, I should have started with the easier wing, so I could build some experience. Oh well.
On the right wing, I could have used more sealant. I’m sure I got a good seal in the end, but I don’t think I hit the goal of 0.7mm between sender and rib. This space is to allow easier removal of the sender in the case of future tank maintenance. With a slight gap, a blade can get in there to cut the sealant. I have some gap there, but I think it’s less than desired. It’s also tricky to get an even torque on the screws around the flange of the sender, it’s probably not exactly square. I checked that the plate is grounded, and it seems fine.
Then it was onto the easier-to-access left wing. This was quick, clean, and came out great. I used more sealer, and ended up with a nice even bulge of seal around the sender flange. Looks to be just right. Hopefully if I have to do maintenance on tanks, it’ll be the left one!
Next up I’ll be installing the tank drain fitting, then pressure testing the tanks for leaks.
Tonight I started on the autopilot servo mounts by tapping threads for the control rods.
Last night and tonight I bent the fuel sender float arms to the right shape and test fit them into the tanks. It’s a bit hard (impossible?) to tell if the floats are exactly where they are supposed to be, since the tanks are already assembled and sealed. Perhaps if I had a tiny borescope I could peek inside the tank drain and see.
These came out ok, and from careful testing, I can tell they are just off the bottom of the tanks (plans call for at least 1/16 from the bottom), and not interfering with the vent lines. I have no way of testing if they are staying clear of the top of the tank.
I can’t do the final install on these until I get another shipment of proseal, hopefully this week.
Tonight I installed the two VA-146 flange bearings, one on each wing. The holes were already final size and deburred, so this was just a case of setting the rivets, easy! the only challenge was working around the wing stand for the right wing (the left is on the bench).
These bearings will hold one of the aileron pushrods attachments. It’s a tube that runs fore and aft, and connects the fuselage pushrod the the one in the wing.