Finishing Kit

September 13, 2012

Pitch Servo Install- continued, Roll Servo, too! - 5.0 hrs.

A very busy couple of months have just slipped by without much progress on the project. Part of the deal I made with my other half in getting an engine, was to get some home improvement projects and honey-do's caught up. So I have been very busy around here. Just not on the project! But I have managed now and then to get an hour or two and move forward on some small items. I'm also going through a learning curve right now, reading and studying about wiring and trying to make some decisions about the plan of action from here forward. When you are finished with the Finish Kit from Vans, you enter a whole new world without much specific direction. It's no longer like you're going through the manual step-by-step and checking things off as you go. You basically know what lies ahead, but there's no specific order laid out for you. You can do it one of many different ways. There seem to be a lot of pathways to the finish line. It would be very easy to spead yourself too thin doing too many things at once, and get to feeling overwhelmed. I'm trying very hard to avoid this tendency. When I start something, I like to carry it through until it's finished wherever possible. Quite a few RV projects seem to come up for sale at this point, I've noticed. I don't want to become a statistic. I want to get this thing finished! I'm more motivated than ever, and more excited, too. The finish line is out there, in the somewhat foggy distance, but nearer than it has ever been.

One thing I do is frequently check the classified ads on, one of my favorite blogs. I have picked up some great deals there! Including the pitch servo that I installed in the fuselage recently. I was waiting for the day when an opportunity would come up to get the second one that I'll need, and it finally came. I found a great deal on one from Stein, so I picked it up. Part of the deal was an opportunity to buy some of his pre-wired "half harnesses" that he makes. I got these at half-price, so I couldn't resist. When they arrived with the second servo, I was thrilled that I made the decision to go ahead and buy them. They're really nice! They have the Dsub connectors on one end. The other end has the pins on the ends of the wires, so when I get the Autopilot installed in the panel, it will be easy to put the pins in the connector at that time.

So here we go... my first wiring job!

It could scarcely be any easier. Just plug the Dsub connector in and tighten the attachment screws. As you can see, I routed the wire through some conduit I installed when I built the baggage area of the plane. Am I ever glad now that I did that! You can see the half-harness from Stein is labeled for the pitch servo. The other one, obviously, is labeled for the roll axis. Forward from here, it goes under the seat, through the wing spar center section, and the coil of wires is now lying on the floor under the panel. It's done for now. I also left a string through the conduit, so I can easily pull more wires through later.

Next, it's time I try my hand at the task of safety wiring. This is a new skill for me. So I prepared to take my time and probably do it several times until I get it right and get the hang of it. Here you can see my tools laid out, along with my book "Standard Aircraft Handbook" that I have used for reference many times. There's a very brief discussion about safety wiring and a diagram or two, but that's about it. I'm going to have to look for some other resources to learn more.

Here's my first attempt! It took me a while to figure out a strategy, get the wire estimated the right length, and then go from bolt to bolt and get it installed. There's an old saying you follow. It goes "righty tighty, lefty loosey". Remembering this makes sure you get it installed in the correct way, to prevent the undoing of the bolt, due to vibration.

I was quite proud of this job. But the more I look at it, the less satisfied I am with it. It looks a bit sloppy, and the wire isn't twisted evenly, especially on the lower horizontal run. I'll probably end up doing it over. I could use the practice anyway. It would be easier if it was on the workbench, but I'm bent over the side of the fuselage in this case. Nevertheless, I went ahead and re-installed the elevator pushrod, and connected the hardware.

September 22, 2012

Well, it's over a week later, but for continuity I wanted to put this on the same page. Since I now have the second servo for the roll axis, I decided to go ahead and install it in the right wing. This definitely presents a different set of circumstances. But first, I decided to go ahead and redo the safety wiring in the fuselage on the pitch servo. Here's my final job:

This time, I routed the wire starting at the bottom left and going right, then up. I'm much happier with this job. UPDATE: December 12, 2013: After doing all this work purchasing and installing these servos, I learned that for the ultimate autopilot experience, there is a different servo for the pitch axis. The basic servo, Model # DSB-B, that you see above will work just fine. But they make a model # DSP-B that includes vertical steering capabilities. Since the autopilot I plan on installing has this feature, and the wiring harness I bought from Stein includes the extra wire for the DSP-B pitch servo, I decided to pull this servo and install the better one. So I sold the servo seen above, and installed the one seen below. And once again, another safety-wire experience.

So now, it's on to the right wing:

I pulled off the access cover and put my shop light inside the wing. It's very straightforward to position the servo in place and bolt it down. There are 3 bolts, two on the side facing me here on the bottom, and a third one on the back side on the top. The TruTrak drawings that came in the installation kit are very nice, but they don't show anything about hardware. Most of it is fairly obvious, but there are some large fender washers, and I'm wondering there TruTrak intends them to go. I think I'm going to send them an email and ask a question or two. I'm also wondering about the length of the pushrod (not shown here) and how long it's supposed to be. The drawing gives no dimensions.

In the picture above, the red arrows point to the two attachment bolts that need to be safetied. This will be straightforward enough. I'll wire them to each other. But the third bolt is on the back side of the servo, on top, as seen below. I inserted my inspection mirror so you can see the bolt head back there. How am I going go safety this? There's nothing back there to wire it to. In addition, these little jobs require some antics, to get your hands and tools inside to get the job done.

I posted these pictures and some questions on the forums on VAF and Rivetbangers, and got some very nice replies from my friends online. So I'll figure out a plan here very soon and get this job finished. When I do, I'll be updating this page.

UPDATE: Well, I did figure something out after all. After looking at a lot of great ways to safety this bolt, I took an easier way out. Getting into the tight space between the wing ribs, working through this small opening with my big hands proved to be difficult enough. Let alone trying to work with my safety wire pliers, on the back side of this servo. So at the suggestion from a friend online, I took the servo out and ran a #12 reamer all the way through this hole, and simply installed an AN3-12A bolt and locknut. Simple! I checked for any clearance issues with the pushrod that will go on here, and there's no problem. I'm glad to have this finished. Sometimes, we overlook a simple solution and complicate things too much!

Now I'll safety the two bolts on the bottom-front and be done with this.

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