Hydraulic Brakes and Rudder Centering Springs




Tracey O'Brien's hydraulic brakes are installed on the plane. Control is by a dual master cylinder mounted on a plate bolted to the cockpit side rails. Dual brakes aren't really necessary on the Challenger. But a stick mounted cylinder prevented full forward stick given my instrument panel layout. The nylaflo hydraulic lines are run aft through rubber grommeted holes in the side rail ribs. Nylaflo tubing can be bent by softening it with a heat gun. Careful not to crimp it or overheat it. Also, don't heat the tubing where it enters the compression fittings on the master cylinder; it's got to be straight and round at that point in order to seal. After filling the system, I found that the handles were uneven at equal braking pressure. Tracey answered my e-mail (he's very accessable via either phone or e-mail) with the solution to shim the pad with less travel. Another item on the to-do list. Seems like as soon as you check one thing off that list, more items appear; anyone else have that experience?







Filling and bleeding the system is accomplished from the bottom upwards. 'A' is a can of brake fluid with a tire valve installed in the cap and a rubber brake hose connected to the bleeder nipple on the brake cylinder. The can is pressurized with a small 12V portable air compresser and battery 'B' forcing fluid out of the can and through the system then out the bleeder valve on the master cylinder and into a waste can through another hose at 'C' . Pump till there's no bubbles (work the master cylinders while pumping) and close the bleeder valves.




I've been told that the FAA airworthiness inspector is likely to look for a rudder centering mechanism of some sort. Here's my solution: 'A' is half of an elevator hinge. 'B' is threaded adjusting rod with a nyloc behind the hinge. 'C' is an internally threaded connector with lock nuts on each end (locktite these nuts). 'D' is a turnbuckle fork. 'E' is the spring pinned to the fork and connected to the rear rudder pedals with a bolt through the pedal. The spring bears on a short piece of tubing placed over the bolt to act as a bearing. this is done on both sides, natch. Does it work? Seems to... Is it necessary? Who knows. But it looks groovy, can't hurt, and is easily removable after inspection if desired..







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