Friday, August 1, 2014

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.