What was found
DURING LANDING ON MAIN WHEEL TOUCHDOWN ALL BRAKES SEEMED TO APPLY BRAKING ACTION IN AN EVEN MANNER, CAUSING THE NOSE TO SLAM DOWN. THE BRAKES CONTINUED TO APPLY BRAKING ACTION TO A COMPLETE STOP WHILE ON THE RUNWAY. WE USED CAUTION WHEN APPLYING POWER TO CLEAR THE RUNWAY BUT MORE THAN NORMAL POWER WAS REQUIRED TO KEEP THE PLANE MOVING. ONCE CLEAR, WE CYCLED THE PARKING BRAKE & ANTI-SKID & RETRACTED THE FLAPS. AFTER WAITING 3 MINUTES THE BRAKES WERE NO LONGER APPLYING BRAKING ACTION SO WE MOVED THE PLANE TO THE FBO. NEITHER PILOTS NOTICED IF BRAKE PRESS WAS REGISTERING ON THE BRAKE PAGE DURING THE EVENT & THE BRAKE TEMPERATURES ROSE EVENLY TO 260. POWERED UP AIRCRAFT AND PERFORMED PARKING AND NORMAL BRAKE APPLICATION. PRESSURE ON SCALE IS SHOWING AS NORMAL. PERFORMED ANTI-SKID UNIT OPS TEST AND TEST PASSED. JACKED AIRCRAFT AND PERFORMED GEAR SWINGS. NOW NOTICED THE LT MAIN RETRACT TIME VALVE ASSEMBLY PLUNGER STICKING AT TIMES AND PRESSURE WILL REGISTER ON TRANSDUCER OR SHORT TIME AND ONCE PLUNGER IS OUT PRESSURE WILL DROP. REMOVED LT MAIN RETRACT TIME VALVE PN: 1159H20265-3, SN: FAH4577 AND INSTALLED NEW VALVE SAME PN, SN: FAH4224 IAW GIV CMP 323084. REMOVED AND REPLACED ANTI-SKID CONTROL UNIT IAW GIV CMP 323084, 324204 AND 323001. PERFORMED GEAR SWINGS, FUNCTIONAL CHECKS AND ALL CHECKS GOOD IAW CMP 32300