What was found
AIRCRAFT WAS GROUNDED: PILOT REPORTS AFTER LANDING ON TAXI IN EXTREME BRAKE PULSING WHEN BRAKES APPLIED. TURNED OFF ANTI-SKID & AIRCRAFT TOOK A HARD RIGHT TURN , SWBACK TO NORMAL, & AGAIN, EXTREME PULSING. MAINTENANCE PERFORMED TROUBLESHOOTING IAW TSM 32-40-00-810-912-A. REMOVED & INSPECTED #3 TACHOMETER IAW AMM 32-42-68. INSTALLED & OPS TEST OK. REMOVED & REPLACED #4 TACHOMETER & OUTERSHELL IAW AMM 32-42-57. PERFORMED OPS OF #4 TACHOMETER IAW AMM 32-42-00, OPS TEST GOOD. BLED BRAKE SYSTEM IAW AMM 32-42-00. PERFORMED TAXI CHECK. NO DEFECTS NOTED.