Vans Aircraft RV-12 Airplane Build, Section 35: Landing Gear & Engine Mount (part 6)

Reference: Page 35-06; 3.0 hours

Today started the process of bleeding the brakes on the RV-12 airplane. What a pain!

Step 7: Fill the brake system with the brake fluid recommended in the wheel and brake package instructions. Follow the instructions in the wheel and brake package for bleeding the brake system (note that the loop around the base of the main gear legs is standard for RV aircraft and has not hindered the removal of air from the brake system).





Builder's note: pictured above is the first bleeding system I used. I later built a pressure tank and used compress air to prime the system. It worked well on the left side but not the right side.

So, after talking with Matco (the brake manufacturer) I discovered if the piston is pressed all the way in (as pictured below) there is no room behind the piston to allow the fluid to flow into the system and press the piston out.


Builder's note: I did have some air bubbles that didn't want to flow out. So I loosened some of the strategically placed fitting and then forced the bubbles out as can be seen below.



Checking the next day I did find a few leaks between the master cylinders and the brass elbows. Some of these I added an extra turn in tightening to stop them and one needed to be removed and resealed. This completed the priming and bleeding of the brake system.

Vans Aircraft RV-12 Airplane Build, Section 35: Landing Gear & Engine Mount (part 5) & misc jobs

Reference: Page 35-06; 1.5 hours

This last week I had another EAA Technical inspection from a different counselor. Jake my old counselor (retired?) in January of this year. Ernie has inspected at least 14 RV-12 constructions and know a lot about their weak point. So there are a few things I am going to correct and I will list them as they are completed and add them to the GOTCHA list.

The first on is were the wires come through the seat rib for the auto pilot servo. As can be seen in the first picture the wires come through the rib but can rub against the edge of the rib. So i install edge grommet to protect the wires.





Reference page 35-07 (previously page 35-06); SB 10-12-14

Inspected the nose fork per SB 10-12-14 and found no manufacturing defects. Step 1: Attach the WD-1201 Nose Gear Assembly to the fuselage using the hardware called out.



Step 3: Tap 5/16-24 the holes indicated in Figure 2 of the RV-12 plans on page 35-07. Thread screws into the WD-1230 Nose Fork Assembly as shown in Figure 2.



Step 4: Grease the SF 4048-16 Bronze Bushings with Aeroshell #5 or equivalent. Slide the WD-1230 Nose Fork Assembly, the two U-611 Washers, and the NAS1149F2090P Washer (The U-611 washers are "cupped", and to function properly, the outside perimeter of both washers must be in contact with each other when installed) onto the WD-1201 Nose Gear Assembly. Finally, thread on the MS21025-20 Nut.





Step 5: Thread safety wire through the bolt holes used to secure the Nose Wheel and Tire Assembly to the WD-1230 Nose Fork Assembly, then attach a spring scale to the end of the safety wire. Tighten the MS21025-20 Nut until a force of 18-20 lbs is measured as the Nose Fork Assembly pivots around the spindle. Use the nut as a drill guide and drill #30 both sides of the nose gear leg for the cotter pin. Deburr as required then secure the nut with the cotter pin called-out in Figure 2.







Step 6: Slide the U-1210A Axle through the bearings, then slide the U-1210B Spacer over the end of the axle as shown in Figure 3. Bolt the Nose Wheel and Tire Assembly, the axle, and the spacer to the Nose Fork Assembly using the hardware called-out in Figure 3. The Nose Wheel utilizes ball bearings that are prelubricated and sealed. The axle nut need only be torqued so that slight drag is produced from the bearings and then backed off slightly (approximately 1/4 turn). Please note that this is different than the torquing procedure used for the main wheel which has tapered roller bearings with an integral grease seal.

I didn't take any pictures of the mounted wheel. Not sure why. But this completes this entry and the installation of the landing gear with the exception of adding brake fluid and bleeding the brakes on the RV-12 aircraft.

Vans Aircraft RV-12 Airplane Build, Section 35: Landing Gear & Engine Mount (part 3)

Reference: Page 35-04, 35-05, 35-06; 6.5 hours

Snowday or airplane workday!!! Today we got hit with the start of the worse snowstorm we have seen in 15 to 20 years. Keep in mind this is nothing like the mid-west but people aren't prepared for this kind of weather in Oregon ( you don't shovel rain)!



So, I worked on a few miscellaneous projects around the RV-12 airplane project. First was to repair some paint ships on the instrument panel. This required removing some of the aluminum from the edge of the panel and repainting.



Next was finishing the inside of the front canopy edge. Recall i put a thin layer of epoxy over it to protect it from any solvents in the paints I will spray it with. It was then coated with UV Smoothprime and sanded



Reference: 35-04

Step 3: Made the brake lines out of 1/4" aluminum tubing supplied by Vans Aircraft. Added fluid nuts and flaired ends as directed.



Step 4: Attached the Main (Plastic) Brake lines to the fittings on the Inboard Main Gear Attach Brackets, using pipe thread sealant.



Step 5: Routed the brake lines down the gear legs and attached these to the brake calipers as direct in the RV-12 airplane plans.



Builder's note: Routing the brake lines is usually done after the main wheel are installed , but I couldn't make it out of the driveway and down to the airport to get the needed grease.



This completes page 35-04.

Reference: page 35-05

Step 1: Secure the Main Brake Line to the center section of the RV-12 airplane fuselage and each other using wire ties.





Step 2: Install the provided clear tubing two onto both the leaft and right main brake lines.

Builder's note: These will be secured with wire ties after the gear is painted.



Builder's note: I am holding off on steps 3 & 4 (adding the Cover plates that fit under the landing gear and installing the inspection covers until I fit the main wheel on the R-12 aircraft.

Step 5; Separated the Anti-Rotation Plates for the front wheel fork.



This completes page 35-05 for now.

Reference: page 35-06

Step 1: I'm holding off on installing the nose gear as it will just be in the way for now. Right before installing the Rotax engine on the RV-12 I will install it.

Step 2: Countersunk the four outboard holes on the nose fork that will hold the Anti Rotatiion plates. Riveted the plates in place.




The remaining steps on page 35-06 of the RV-12 airplane plans, deal with the front nose gear and fork. I will complete these later.