The piston insulator is removed from the pistons,
REASSEMBLY.--Reassembly of the trimetallic
and the pistons are removed from the brake housing by
brake is essentially in the reverse order of disassembly.
threading a return pin into the threaded hole in the
Lubricate the packings, retainers, cylinder walls, and
piston and pulling slowly. Exercise care to avoid
other contacting surfaces within the brake housing
damage to the seal groove and cylinder walls. Remove
with a light coating of MIL-G-81322, general-purpose
the bleed valve assembly and the brake inlet plug
a i r c r a f t g r e a s e b e f o r e r e a s s e m b l y. A p p l y
assembly.
MIL-G-6032B grease to the piston side of the piston
insulators. Lubricate the brake housing bolts and the
CLEANING AND INSPECTION.--Dust and
contacting surfaces of the bolt heads with antiseize
loose grit are removed by using low-pressure air, and
compound. The coating of these bolts and the
then all parts are cleaned in a P-D-680 cleaning solvent
contacting surface of the bolt heads, followed by
and dried with a clean, lint-free cloth.
torquing, are referred to in some MIMs as "Lubtork."
All metal parts are visually inspected for cracks,
TESTING.--The reassembled trimetallic brake
w e a r, o r o t h e r d a m a g e , a s s p e c i fi e d i n t h e
must be tested to ensure the quality of maintenance.
"Intermediate Repair" section of the MIM. Some parts
Connect the brake assembly to a hydraulic test stand
may require inspection by one of the nondestructive
and apply 25 psi to the inlet port. Open the bleeder
methods. The return spring is inspected for proper
valve until air-free fluid flows from the valve. Increase
resilience. The amount of force required to move the
the pressure to 1,000 psi for 2 minutes and check for
grips on each tube and grip assembly is checked with a
leaks. Relieve and reapply 1,000 psi several times, and
special tube and grip tester.
then release the pressure slowly to 90 psi. Holding the
The rotating disc is inspected for cracks,
90-psi pressure, measure the clearance between the
distortion, and thickness. The disc must be replaced if
pressure plate and the first rotating disc. Minimum
it is worn below 0.2-inch thickness, if it is cracked, or if
clearance must be 0.065 inch. If used discs were
the friction mix is worn unevenly. The friction mix
reinstalled, check for proper rotation. Secure the test
may be pitted up to 0.5 square inch in any segment.
stand, disconnect the brake, and plug the inlet port to
The stationary disc is inspected for cracks and
prevent contamination.
thickness. If the minimum thickness is less than 0.3
Q14-31. During single or dual brake assembly
inch or the disc is cracked, it should be replaced.
maintenance, what prevents the piston from
returning to its original position when the
The backplate and pressure plate should be replaced
brakes are released?
if they are cracked. If the wear pads are worn to less than
0.088-inch thickness, they should be replaced.
Q14-32. What fastness the wheel brake disc guide
linings to the disc guide?
WEAR PAD REPLACEMENT.--Wear pad
replacement on the pressure plate and the backing plate
Q14-33. How long should you hold the brake pressure
is authorized. Drill out rivets that hold the worn pads.
when testing for fluid leakage and proper
Discard the worn pads. Check the plates for cracks,
operation on the duel disc brake assembly?
deformation, and rivet hole elongation. Use a standard
Q14-34. As brake disc wear occurs, what components
squeeze rivet machine to rivet the replacement wear
provide automatic adjustment through the
pads to the plates, using the type of rivet specified in
split collar?
the applicable MIM. The rivet bucktail must be below
the surface of the wear pad. Rivets with more than one
Q14-35. What is the minimum percentage of the
crack visible in the bucktail or with less than 50 percent
circumference allowed on rivets used on the
wear pad of the formed head flush with the
of the circumference of the formed head flush with the
sides of the countersunk area?
sides of the countersunk area are not acceptable. The
new wear pads must be surface ground to 0.100-inch
thickness, and should be flat within 0.010 inch after
SKID CONTROL SYSTEM
grinding. The reworked plates should be vapor
MAINTENANCE
degreased to remove all oil and grinding material. The
dried plates should be wrapped in clean, heavy paper
for protection until they are replaced in the brake
LEARNING OBJECTIVE: Recognize the
assembly.
o rg a n i z a t i o n a l - a n d i n t e r m e d i a t e - l eve l
14-36
