(c)
Reconnecthydrauliclines and bleed brakes.
(d)
Reinstallwheel by slowly sliding it over the axle. Align the brake disc-carrierteeth with slots in the wheel.
(e)
Install axle nut ensuring the bearingsare seating properly. (Refer to 32-40-00 Assembly and Installationof Main Wheel.)
EFFECTIVITY:
32-40-00
Jan 10/90
PIPER AIRCRAFT
PA-42-720(Advanced Trainer)
MAINTENANCEMANUAL
B. BrakeAssemblies (continued)
5. Inspection of Brake Assembly
(a) Inspect O-rings for nicks, distortion,or excessive wear. Replace as necessary.
6. Cleaning of Brake Assembly
(a)
Except for disc-carriers and lining assemblies,clean all metal parts with a Stoddard solventor suitable equivalent.
(b)
Remove and clean O-rings with denaturedalcohol; dry thoroughly.
(c)
If the finish on torque plateor housing assemblyneeds refinishing or removal,use the following instructionsto remove old paint from metal surfaces.
NOTE: It is not necessary to strip paint on assembly to inspect using dye-checkor fluorescent penetrant.
7. BrakeWear Limits (referto32-40-00 Chart 3)
BREAKWEAR LIMITS
CHART 3
Disk Carrier and Carler, Lining and Inspection Areas Linign Assembly Torque Button Assys
Thickness Max. 0.519 0.265 Min. *0.370 *0.160
Dishing Max. 0.050 +0.025
(Flatness) Min. 0.000 0.000
I.D. Max. 7.000 7.000 Min. 6.800 6.800
*Minimumthicknessis85 percent of lining surface. This is an overhaul limit only.
Parts may wear beyond thesedimensionsin service.
+Carrier,lining,andtorquebuttonassembliescan be cold flattened with a mallet and flat plate. Check flatness on lining side of segment.
Inorder to preventpremature removal andsubsequentoverhaulof brakes still serviceable, B. F. Goodrichhasestablisheda brake removalwearlimit (BFG S/B 399)checkprocedure. Proceedas
follows:
(a)
Pressurizebraketo 100 psi.
(b)
Measuredistancebetweenthe carrier. Lineandtorque button assemblyand the piston housing (refer to 32-40-00 Figure 404). (A 0.350inchmeasurementindicatesbrakeneedsto be overhauled.)
EFFECTIVITY:
040-999
PAGE16
Jan10/9032-40-00
PIPER AIRCRAFT
PA-42-720(AdvancedTrainer)
MAINTENANCE MANUAL
B. Brake Assemblies (continued)
8. Removal of Brake Master Cylinder (referto 32-40-00 Figure 405)
(a)
Ensure all hydraulic pressure is off the brake system and parking brake is off.
(b)
Disconnectand cap brake lines from the affectedcylinder to prevent contaminationof system.
(c)
Removebolt connecting boss end of brake to its fitting or channel assembly. Remove the bolt connectingbrake rod end bearing to pedal attaching arm.
(d)
Remove cylinderfrom aircraft.
9. Disassemblyof Brake Master Cylinder (referto 32-40-00 Figure 406)
(a)
Internal parts of brake master cylinder are removed by removing the snap ring from the annular slotat the lower end of the cylinder. Pull completepiston assembly from cylinder.
(b)
Slide the packinggland, O-ring, washer,and spring from piston rod.
(c)
The piston valve assembly is removed by taking off the self-locking nut from the piston rod, allowingthe piston with component parts to be removed.
10. Assembly of Brake Master Cylinder (referto 32-40-00 Figure 406)
(a)
InstallO-ring on cylinder piston and assemble the piston, spring, washer seal, and valve onto the piston rod. Allow the valve to extend into the base of the piston. Slidethe O-ring and washerin place. Secure with self-locking nut.
(b)
Install O-ring seal on packinggland and slide spring, washer,O-ring, and packing gland onto piston rod.
(c)
Dip piston assemblyin hydraulic fluid (MIL-H-5606) and install assemblyinto cylinder. Push packinggland into cylinder until snap ring can be installed into the annularslot at the bottom of cylinder.
11. Installationof Brake Master Cylinder (refer to 32-40-00 Figure 405)
(a)
Compresspiston within cylinder. Adjust rod end bearing so the total length (refer to 32-40-00 Figure 406).
(b)
Withcylinder ports towards the front of the aircraft, mount boss end of master cylinder to the fittingconnecting the cylinder to its support assembly.
(c)
Connect rod end bearing to its rudder pedal control arm.
(d)
If brake pedal is out of alignment with other pedals, adjust by disconnecting the rod end in or out,whichever is required.
(e)
Remove caps from hydraulic lines. Reassemblelines with supply line attached to the upper port and pressure line attachedto the lower part.
(f)
Bleed brakes and ensure no sponginess exists in the operation of the brakes.
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