Fabricating the right cockpit brake line - 6 hours

 I'm really struggling with what to do for the cabin area brake lines. Originally I was thinking braided nylon brake lines. I also feel pretty confident in making them out of 1/4" 3000 series aluminum.  Each has its pros and cons. (Braided lines are easy, but they make the braking feel less firm and they don't bend corners as well. I know I will have space issues with my install. Hard lines are difficult to fit, but are cheap and fit in tight spaces). The disadvantages that I am focusing on right now are the braided line is how to insert the tubes through the cover support ribs on the front of the spar. The holes are not large enough for the fittings so I would need to do some surgery. The difficult part with the aluminum lines is getting the line through the gear weldment and flaring them in place for the fitting through the bottom of the skin.

I finally decided that I will at least attempt to make them out of soft aluminum tubing and if I fail, I'll go with the braided lines. After a couple hours making templates with scrap tubing. I finally figured out my bend recipe. I made the complete right brake line, and fit in into the plane. Getting the tube routed through the gear weldment was interesting (a pain). Turns out that I just struggle too much trying to flare that end near the weldment. Also take into the account if I ever have a leak or need to replace this line...This is likely impossible to re-do when the plane is complete. 

 

It just wasn't working to my liking, so I abandoned the idea. I was deflated. I wasn't fully on board yet with switching to braided lines. Getting the cover support rib issue worked out was not going to be fun, nor easy. After some head scratching..I though back to a suggestion from my buddy mike who mentioned a bulkhead fitting in the cover support rib could be an option. Well that does solve the impossible part of the aluminum tubing option. 

 

 I went to work again...this time using a bulkhead fitting in the most outboard cover support rib. Yes, is slightly interferes with the lower hole. But if I shave down that one flat on the fittings...Bingo! We have a solution. I started working away at making a couple of lines again and by the end I have my bend recipe for the right brake line worked out. 

Measure out 50" of tubing and straighten it. 

1. Start with flare for the firewall fitting. 

2. Measure 2 1/2"

3. Bend 45deg aft. 

4. Allow short length, bend 60deg fwd.

5. Immediately bend 30deg aft so the tube is back parallel (For and offset S bend....yes the math doesn't checkout but with the consecutive bends in my tool, the original bends relax a little)

6. Measure 3", bend 90deg down.

7. Measure 2", bend 90deg aft

8. Measure 24", bend 75deg up.

9. Measure 1 1/2" (or just a tad more), bend 90deg to the right side of the plane. This gets the line through the large "S" in the fuel supply line 

10. Measure 3 1/2", bend up 30deg, Allow about an 1" then down 30deg (For an S bend). This will allow the line to get up and through the first inboard cover support rib.

11. Measure about 2", bend up 30deg, then down 30deg (For another S bend). This gets the tube aligned for the outboard support rib/bulkhead fitting. 

12. Trim to final fit (you will remove about 3/4"). Slide on the bushing, the AN collar and nut. Then bend the tub fwd enough to allow a flare to be fabricated. Bend the tube back by hand to the bulkhead fitting.   

Started fitting the AN837-4D elbow - 4 hours

 Time to get started on the brake lines. One item that I didn’t do yet was fully open the pilot hole for the brake line fitting in the F-772 forward bottom skin. The reason why is I want to make absolute certain that hole is centered in the opening in the weldment.

This is a very time-consuming process but my previous dry fitting showed that the holes are just a tad off. To start, I made sure the hole was centered. Then I started opening up the hole. Of course, I can’t use a unibit without damaging the weldment. So lots of work and lots! of time with the Dremel.

 

 

Aluminum tubing tools

For reference. I have the following tools for bending and flaring my aluminum lines;

• Imperial 470-Fh Triple Head 180deg Tubing Bender (From Aircraft Spruce). I've but some gorilla tape on the underside of the lip as the tool likes to mar the aluminum there. I use air tool oil to help lube the tube before bending.
  

• Rolo-Flair manual rotary flairing tool. (From Aircraft Spruce). This is a big bulky unit. It works great but its big. I use a drop or two of air tool oil on the flare face and then use some 400 grit sandpaper on the outside of the flare edge.
  
  
  

•  1/4" handheld tubing straightener (From Amazon.ca)
  
  
  

 

Installing and then uninstalling the park brake - 2 hours

 I installed the Matco PVPV-D park brake on the AirWard brake adapter, then temporarily installed the rudder/brake pedals. It became very clear that I was going to have clearance issues if the rudder pedals are full forward. Since I am quite tall (6'-3") I need ever inch I can get. 

 

 I am going to have to abandon the plan of installation. I really struggled with what to do now. Do I just go back to the standard Vans installation and not have a park brake. Doing some reading on this, The opinions are divided. Some say no, some say its a must. Its not easy decision to just omit it. 

 I ran the options with my buddy Mike and we ended up agreeing not to abandon the installation of a park brake. We figured that we can install the AirWard mount, but just up higher on the fire wall. This solves the issue of clearance and gives me the freedom to mount the park brake any way I want. It also gives me (or any future owner) the option to use, or bypass the park brake. 

Glad that I have a clear idea of how to proceed. I removed the AirWard adapter, and re-installed the  F-6122-1 bracket.

Touch-up proseal on side steps - 2 hours

 I need to touch up the proseal on the side steps. I do not want water to sit on the top of the side step flange, so the best solution is to have a good fillet of proseal on the top and sides of the side step. I don't enjoy working with proseal so lets just get this over with.

 I applied a health fillet of proseal around the side step. As well I used a syringe to get proseal tucked into the corners. 

 A bit of proseal as well along the bottom skin of the wing area.

 Then I bunch of cleanup with a rag and MEK. Yuck I hate this stuff.

Since I have a little time on my hands. I also installed all of the ends on the control rods and push tubes. I torqued all of the Jam nuts.

 UPDATE - Don't bother installing the control rod ends and jam nuts on the F-789 pushrod. In order to fit the rod into the fuse they must be removed and installed once the pushrod is slid into place.

 

 

Fabricating the F-789 Elevator push tube - 2.5 hours

 The last push tube to finish is the F-789 elevator push rod. Again I used Autocad to work out the rivet spacing 

The lines are marked on the tube, and drilled in the drill press. 

The same prime and paint process was used, and by the end of the evening I have the push tube primed and assembled and late evening I was able to spray a couple of coats of final color. 

During the day, a local builder Tracy Trathern who has a beautiful RV-7A dropped by to look in on the project. He also dropped of an ELT that he was selling. So I am now a proud owner of an Artex ELT 345. I will need to figure out how to mount this on my plane. 

More fabrication of the pushrods - 3 hours

 Todays build was not that long. Just the logistics of this particular build, need to finish this aft pushrod in order to finalize the forward elevator pushrod. 

The manual has you confirm correct position of the pushrod in that the bottom bellcrank bolt is entered in the opening (using a socket) when the elevators are perfectly neutral/aligned with the horizontal stabilizer. Once this was set. I made my reference lines, measurements and began cutting the pushrod accordingly. Van’s dimension is extremely close to spot on. 

 

I then could drill the aft end of the pushrod for rivets. Now….priming the inside of that tube was an incredible pain. My quart can of 1K primer that I used on the wing tubes was rock solid cause it sat so long. All I have now is 2K epoxy primer. I mixed up a small amount and dumped it into the tube and worked it back and forth. WOW is that stuff heavy. It’s so thick inside trying to do it this way. Eventually I abandoned this idea and cleaned the entire tube out with MEK and a rag, pushing it through a few times with a long stick.

Instead I used the self etching rattle can primer. Using the included narrow nozzle and spraying down the tube from each end. Not 100% prefect. But at least its not super heavy. 

I could then install the primed ends into the tube and rivet. 

 

Once riveted and a bit more primer. I gave a final paint coat later on in the evening.