PropJock

November 19, 2011. 3.9 hours and lots of cogitating.

I have figured out 3 ways to mount the Whelen strobe power pack on my plane and built two of them. The third way is to mount it on the deck of the tail section under the vertical stabilizer. I trashed two of the ideas and went with imitating the Van’s mount on the side of the plane behind the baggage compartment. Actually I made two mounts, one for the right side and one for the left. I made a cardboard mockup and then cut it out of aluminum sheet. I put the strobe power pack on the right side and I’ll put my ELT on the left.

There’s not a lot to this process. I cut a rectangular piece of aluminum out of 0.32 material and then bent a tab to mount to the J-Stringer and then cut the bottom of the sheet to parallel the lower J-stringer. I bent 1″ tabs to off-set the mount from the side of the plane. I then marked the mounting holes for the power pack and installed platenuts and then used pulled rivets to attach the mounting plate.

I’ll mount the ELT after I buy it (likely this week) and then after running wires for the ELT, the magnetometer, and the strobes, I will be ready to cover the top aft fuselage. That deserves a big “woohoo” like only my wife can do.

Spruce Aircraft says the tubing should be here Monday to do the fuel lines and brake lines and Stein Air says the wiring I need to wrap this up should be here before Thanksgiving. My goal is to have the fuel lines done before we go to Mooresville for Thanksgiving.

11/13/11, 3.1 hours

I started off today by trying to fix the doghouse cover over the fuel pump. I spent an hour working on sorting out the problems – and there are several. It just got too frustrating and I put it down for now. It can be fixed, I believe, but it is going to take some work. I think I turned my brain off when I assembled the parts.

So, I moved on to some other things that needed fixed. There’s a long countersunk screw that connects the ailerons to the control rod that goes back to the aileron bell crank. Well, I’d made all the spacers and inserted all of washers per the plans and ground the screw to length – the maximum possible length that didn’t crush the aileron skin. The end of the screw came just to the end of the nut. The rule of thumb is there should be 2 threads showing past the end of the nut. To accomplish this I’d need to either crush the edge of the skin, or remove some skin, grind another screw a little longer, and install it. I did just that. I got two threads to show on each side.

I next reinstalled the flap control rods and looked for interference. My recollection was there was a little on the right side. I couldn’t find any interference but both sides were a bit close in one spot and I relieve the fuselage to allow a bit more clearance.

Next, I reconnected the ailerons and looked for interference on them. Talk about close tolerances! Moving the control stick you can’t feel any interference but inspecting the control rods showed the powder coating was wearing off the outer edge of both control tubes at max deflection in that direction. It appears I need to remove about 3/16″ of metal to assure full freedom of movement. That’s easy to do – removing the control rod in order to do it is a bit more challenging.

Lastly, I figured out where an how to mount the Whelen strobe pack and I made a rack for it and have it about half assembled. Now I need to figure out where to mount the aft strobe. The obvious spot has a flat for the light but no possible way to access the nuts to affix the light. This stuff should be easy, but it isn’t.

I still need to plumb the fuel lines. No magic plans are coming to mind to make this an easy project.

11/12/11 2.6

That’s not misprint – I worked the same number of hours today as yesterday. As hard as it is to believe, all I accomplished was getting the magnetometer shelf finished and installed. The shelf itself is pretty simple. The tough parts were installing the shelf so that it was level in both roll and pitch, and parallel to the center line.

The F707 bulkhead is so flexible that I decided I should rivet the shelf to the left J-stringer, then install the forward of the two aft skins, thereby putting all the part into their final position, and then position and drill the right side of the shelf to the top central rib behind the F707. Positioning the shelf correctly was critical. Once I got it positioned, I removed skin, drilled the holes and finished riveting the shelf in place.

11/11/11 2.6 hours

After talking to another builder friend about how he routed his wiring, I realized that I forgotten to put two holes in the F707 bulkhead. With all the control tubes, the bell crank and the AP servo, access wasn’t quite as easy as it would have been had I not forgotten to drill the holes…but it was possible. Most of the first hour doing this task was spent taking the control tubes off and then reinstalling them.

After getting the holes in, I started making a shelf for the magnetometer. It’s hard for me to imagine it took more than 90 minutes and five rather simple parts were not done. In fact, I actually made two left hangers when I needed a right and a left. Time to quite after a ‘brain fart’ like that.

1 hour

Nothing accomplished beyond a lot of head scratching. Not sure how to install the fuel line to the Andair valve, passing it through two plastic bushings along the main spar, through the gear web, a couple of bends and out the fuselage to the tank. After a lot of cogitation and some consultation, I’m going to try bending the parts into place and flare them after they’re in place…or nearly so. This means the last flare won’t happen until the wings are back off. I’ll try and leave some extra tubing in case of I need to repeat a flare. If noting else, I know the 3/8″ tubing is easier to flare than the 1/4″.

10/29/11 2.0 hours, 535.1 Fuselage Build Time, Total Build Time 1148.1

It has taken a fair amount of preparation to get to this point – most of it rather frustrating. In any event, I’ve been reading about problems with poorly done plumbing and how to do it right. There is some skill in getting the 37 degree flare formed correctly and installing it without over-torquing the fitting, which could cause a leak in either the fuel or the brake system, since they both use aluminum tubing and flares.

I decided to make a few practice flares and measure them carefully to see how they compare with the book specs. It took three tries to get my first one that wasn’t under-flared or over flared. Both rejects looked good to the naked eye. I inspected every flare with a magnifying glass. I decided to start by plumbing the vent system for the fuel tanks. Basically the first part consists of a connection at the tank, a penetration through the fuselage, a bend and another fitting that connects to an ell mounted on an aluminum angle. Both ends are flared, and there’s a B-nut and sleeve at each end. The sleeve and B-nut have to go on BEFORE the flare or they won’t fit. The B-nut and sleeve also have an orientation and if you mistakenly put one on backwards, the only recovery is to cut it off and start over. The second piece is much longer but is only flared on one end, then follows a path up to the longeron, forward to the firewall, then down and exits through the floor of the fuselage.

Since this was the first time I had done this work, since I generally dislike plumbing, and since I didn’t have a mentor to comment, I went slowly. I think I made three attempts to bring the vent line into the fuselage before I got one I liked. The long piece that continued on was a snap to make and not hard to bend either. On the other side I made the tube that brings the vent in correctly on the first attempt.

Note: I am using the material supplied with the kit to make the vent lines. All of the material is 3003 aluminum. Certificated aircraft use 5052 tubing for brakes and fuel lines. The best I can say is 3003 appears to be adequate for the job given the history of the RV series of aircraft. 5052 is roughly twice as strong and apparently is a bit more forgiving in several ways. My plan is to make the remaining parts using 3003 and call them practice parts. I’ll order 5052 tubing and do the fuel lines and the brakes a second time – and with some experience under my belt.

(photos to come- I left my camera in NC last week)

10/29/11 3.1 hours, 533.1 Fuselage Build Time, Total Build Time 1146.1

Fit, drilled, deburred, dimpled, and riveted the fuel pump housing, including installing 8 #6 platenuts. On the bright side, I located 6 out of the 8 correctly. The other two are almost, but not quit close enough. The housing sits just a bit crooked and while I’m sure it would be good enough for a spam-can, I don’t want to look at it and constantly know I could have done it right (or at least better). It probably wont take more than an hour or so to fix.

I’ll also note that I made my worst riveting error to date on the housing. I am not sure how, but l smashed one edge of the housing on my very first rivet. It is pretty thin material (just guessing 0.020) and you can feel it give. Fortunately it is relatively easy to repair with a block and hammer.

Lastly, I’ve decided to “upgrade” the aluminum tubing that Van’s supplies for the brakes and fuel lines from 3003 to 5052, which is actually made for this purpose. Given the critical nature of the parts, and my inexperience, I will use Van’s material to practice on and then make the real parts from 5052.

10/28/11 2.6 hours, 530.3 Fuselage Build Time, Total Build Time 1143.0

Made the cuts required to fit the new base that the fuel pump rests on to the center tunnel cover. I installed the platenuts to secure both parts to the fuselage floor. Van’s isn’t exactly “cheap” but they certainly are frugal. You need four platenuts to secure each part. You have to cut two of the platenuts off, so you’ll need six more. Van’s sends you four and I guess he assumes you won’t use the others. In my case I drilled them out and reused them. Two extra platenuts would cost 96 cents retail.

I mounted the fuel pump and filter and removed the rudder trim cable. I still need to assemble the cover for the parts (as in riveting it together) and install more platenuts to secure the cover to tunnel and fuel selector mount. After that, I’m ready to start plumbing. Woohoo.

I’ve been reading on about plumbing the brakes and fuel lines. It appears that these part are among the most technically challenging to do correctly and also have the greatest risk to life and limb if done incorrectly. I plan to have my work carefully inspected by someone who understands what the parts should look like. It seems fortunate to me that I’ve done this research – more than just about any other part of the construction. This is part of the “educational” aspect of the build.

10/26/11 0.5 hours, 527.7 Fuselage Build Time, Total Build Time 1140.4

I discovered, about a month ago, that fuel injected engines need a high pressure pump and filter. I just knew this wasn’t going to be a $50 item and it wasn’t. $660 + shipping and handling later, the pump and filter arrived. I spent hours reading the shrunk down drawings trying to figure out how the plumbing fit together and how the new pieces fit together. The mounting kit requires some pretty substantial modifications to the center tunnel cover, the box the fuel selector and manual elevator trim rest on and the angle that the trim control sits. I spent thirty minutes stripping the protective plastic off and assembling the housing, and marking the cuts I needed to make in the tunnel. Maybe I was premature in having Steve do the painting…or maybe I need to invite him back to do some more.

10/23/11 3.6 hours, 527.2 Fuselage Build Time, Total Build Time 1139.9

My son-in-law Dennis and a friend, Gus, came over and helped me remove the wings so I could drill two holes on either side of the plane; one for the fuel line and one to vent the gas tank. I spent about an hour disconnecting everything holding the wings to the fuselage…and one of the lower bolts on each side was a real challenge to get out. When Gus arrived we started and for the most part the job went smoothly. Between Dennis and Gus following directions and figuring out how to get the task done, I think the actual time spent pulling, drilling, and reinstalling the wings was 45-50 minutes. Teamwork!

After a little lunch I went back to work fitting the vent lines only to discover that the 37 degree flaring tool I bought used on Van’s Air Force was really a 45 degree flaring tool. Not suitable for aircraft work. This was my second flaring tool. Someone borrowed and never returned my first tool. I’ve borrowed a tool to use this week.

After that I gave up and thought about where to mount my AHRS (Attitude, Horizon, Reference System). No decision yet. I also need to mount the magnetometer and I’m thinking out in the wing will be a good place. The instructions said the AHRS should be mounted in the cabin to reduce the risk of condensation. There’s not a lot of places in the cabin. I’m wondering if there’s a place behind the panel and wondering how much EM the radios will be giving off. I’ve also considered putting in the aft fuselage.