—NOTE—
By watching the fluid pass through the plastic hose at the fluid reservoir and the
bleeder fitting on the gear being bled, it can be determined whether any air is left in
the system. If air bubbles are evident, filling of the system shall be continued until
all the air is out of the system and a steady flow of fluid is obtained. Should the
brake handle remain spongy, it may be necessary to disconnect the bottom of the
toe brake cylinders (next to the pedal) and rotating the cylinder horizontally or even
above horizontal and by use of the hand brake alone, purge the air from the
system.
d. Close the open bleeder fitting to which the pressure hose is attached. Do not remove the tube from the
fluid reservoir until both brakes have been bled. Check the brakes on the side being bled for proper pedal
pressure. Replace cap on bleeder fitting.
—NOTE—
It may be necessary to remove any trapped air in the top of the wheel brake unit by
applying pressure to the system with the brake hand lever and slowly opening the
bleeder and release the hand lever.
e. Repeat steps b through d to the left main landing gear.
f. Drain excess fluid from the reservoir to fluid level with a syringe.
7-49. BRAKE SYSTEM LEAK CHECK. Pull for a good, firm hand brake and lock parking brake mechanism.
Allow system to stand for approximately 10 minutes, then by gripping the park brake handle it should not be able
to be pulled aft further than the original set. Should the handle be able to be pulled towards the panel and feel
spongy, a leak is present at some point in the system. This leak may appear at any one of the connections
throughout the system or internally in the master brake cylinder or wheel brake assemblies.
7-50. BLEEDING OF THE BRAKES AFTER A UNIT HAS BEEN CHANGED.
a. Actuate the hand brake handle until some pressure builds up in the system. At this time. crack the
attaching B nuts at any of the hose connections of the replaced unit. Most of the handle sponge feeling should be
displaced by this action.
b. Actuate the master cylinder and the toe brake cylinder of the side unit was changed and bleed fluid through
the brake assembly on the wheel by pumping pressure and cracking bleeder until pressure drops.
—CAUTION—
Do not allow pressure to bleed off before closing bleeders, for this will allow air to
enter the system. Repeat the pumping and bleeding approximately 10 or more
times or until all the air is released from the system. During all bleeding, fluid level
of the reservoir must be maintained.
PIPER AIRCRAFT
PA-28-161 CADET
AIRPLANE MAINTENANCE MANUAL
Issued: FEBRUARY. 28, 1989
LANDING GEAR AND BRAKE SYSTEM
1I20
