When dealing with Brians boosters what is the second bleeder on the booster for? I use it to dampen the sensitivity of the booster. Do you need to drain these boosters in entirety if you are not having large issues as I have only a soft sponge feel after the winter.
John
John,
That is there to bleed out entraped air in the cylinder. Otherwise, you get a soft pedal. Here are the bleeding procedures for cubs. Note items 5, 6, 7, 9 and 10.
Bleeding procedure for Cubs:
1. Remove cap from reservoir to observe fluid level.
2. Close bleed valve on master cylinder.
3. Attach pressure vessel at the wheel, and pump fluid up through master cylinder into reservoir, until ¾ full.
4. Close off bleeder at wheel and disconnect pressure vessel.
5. Open bleeder at master cylinder and allow fluid to bleed out from reservoir until fluid is observed exiting out of bleeder valve.
6. Replenish reservoir and pump up pressure with pedal by hand, hold pressure, and crack bleeder valve on master to allow air to escape. This is similar to bleeding your car brakes. Continue process until all air is purged, and pedal becomes hard.
7. Once air is purged from master, air can still be trapped back at the brake cylinders at the wheel. If brake feels soft, push pedal down and lock parking brake, then crack bleeder at wheel cylinder to allow any trapped air to escape. Release parking brake to allow fluid to replenish in master from reservoir. May require more than one attempt to purge all the air. Use a second person is no parking brake valve is installed.
8.Replenish the reservoir and replace cap.
9. You may need to crack the bleeder valves a second time after aircraft has set overnight.
10. “CAUTION” all the air must be removed before brake will work correctly. A “soft” brake usually means air is trapped somewhere. It is also important that a few thousands of play is present between end of shaft and brake pedal to insure full travel to operate internal check valve.
Brian.