Tag Archives: lights

LH Landing Light – Lens Retainer Strips

Several months ago, I’d taken a look at the landing/taxi light lenses and what it might take to mount them nicely. The LH wing panel was sitting horizontally on a workbench at the time.

About the first thing I noticed was that the mounting holes around the perimeter of the lens did not all correspond to the holes in the wing where the lights and the lens go. The holes lined up (pretty well) with the lens on the outside of the skin, but not when I put the lens in the opening, behind the skin – where it really belongs.

The other thing wasn’t really so much something I noticed, but rather, I realized that I needed to find a better solution for mounting the lens than the factory provided for – sheet metal screws through the skin and into the plexiglass lens. That’s just not going to cut it.

Now I had another classic opportunity for inspirational procrastination. I put the time to good use. It took weeks, but once again – procrastination paid off! The idea of retainer strips with anchor nuts came early. I also found that I’d likely use #4-40 hardware, because metric MK-1000 nut plates are absurdly expensive and challenging to source in the US. I hate mixing hardware standards on this bird, but that’s just how it goes. The blind anchor nuts on retainer strips behind the lens stuck in my head as an obvious solution.

What was not obvious to me at the time, was how to hold the retainers in place so that the lens could be fitted and fastened with the little screws. I made a prototype with a hand-cut strip of 0.020 aluminum and held the anchor nuts with AN426AD-3-3 solid flush rivets. The strip was flimsy and I attempted to hold it against the backside of the lens with – if you can believe it – sewing thread. Once I got the screws started, I’d pull the thread out. I was too unwieldy.

Weeks went by. Then it hit me – the same basic idea, but with 0.5 x 0.025 stainless steel strips, held to the plexiglass lens with little #4 CSK screws and ny-lock locknuts. I had to make new holes in the bottom half of the lens to match the wing, made six retainer strips and mounted them to the lens. Now I have a lens that is easily installable and removable. I’ve come to believe that this is what the factory does for the Sling TSi and I might have seen it if I’d looked at the TSi construction manual. Oh well. I got there. I’ll repeat the fitting and fabrication process for the RH lens assembly.

Starting Off On the Right Foot

I ordered my quick-build kit in July and I’ve had my empennage sub-kit since August, but have yet to pull my first rivet. I’m finding that it’s taking many hours for research and for me to learn enough background information to make confident choices that will set the direction and metrics I will endeavor to satisfy as I build. I think that’s part of the fun.

Surface priming – materials and techniques – is a significant matter. I’m still wrangling a bit with that, but have determined that I have to be practical, or I’m never going to put pen to paper, so to speak. My priming standards are going to fall somewhere closer to the minimum of bare aluminum rather than the extraordinarily high level demonstrated by the truly awesome work of Pascal Latten for his Sling 2 build. Spray painting can be a messy and tedious business. I’m not a professional and I want to keep things clean and simple as possible, while achieving a worthwhile result. In a nutshell, I’m going to use RustOleum self-etching aerosol primer for most internal mating surfaces. For more exposed areas, such as the hinge areas and outward facing structure of the horizontal and vertical stabilizer assembies, I’ll use Alumiprep 33 and Alodine 1201, coated with more durable PTI 2 part epoxy primer – and ultimately the final color top coat.

Wiring, VOR antenna and external lighting choices figure in early for the empennage build.

Aveo Engineering produces what I think is the best option for the anti-collision light atop the rudder. For reasons that included fit, features and color, I’ve opted for the aviation red Posistrobe MiniMax to complement Aveo 3-in-1 nav/position/strobe lights on the wingtips – exact model number of the wingtip lights TBD. Without a huge amount of work, and or ready access to a completed Sling 2, it’s really mostly an educated guess that the overall lighting results will satisfy FAR 23.1385 – 23.1401. Hopefully it will and the DAR will agree.

Rudder Cap Strobe Mounting Area – small, even for the 1.74in wide MiniMax Light

Working through the electrical current requirements of the LED rudder strobe against AC 43.13B, I’ve tried to determine the necessary gauge and then acquire M27500 shielded cable to replace the TAF-supplied PVC jacketed wire in the kit. Based on actual experience with such wire in my Warrior, I’m not impressed with its suitability for aircraft applications. Based on my calculations, I think readily available 22 gauge conductors would be sufficient to handle peak current less than 3A over a run of 20ft. But, based on some data from the awesome builder I mentioned earlier, it’s possible that 20 gauge wire would be a better choice. I ordered some M27500-20TG4T14 from WireMasters. The minimum order was 100ft. This wire may turn out to be overkill for the small LED light. We’ll see.

You’ll find a chart like this in AC 43.13B

The VOR/GS antenna gets built into the vertical stabilizer, so I have to make a commitment to that, even before I’ve settled on my avionics choices. I’m hopeful that conformance with FAA TSO: C34e, C36e, C40c will make my choice compatible with whatever I finally choose for a VOR/GS receiver. Keeping the antenna price down will also make it easier to go with only a GPS navigator. At least the antenna and wiring will be in place. I’ve opted for the Rami AV-520 which has 2.5in diameter base “puck” with removable whips, built-in balun and coax connection.

I’m aiming for an advanced IFR all-Garmin EFIS panel with autopilot. We’ll see where it ends up.

I’ve ordered a bunch of stuff and it will be here next week. I’m perilously close to the official start my Sling 2 build.