What was found
DURING CLIMB BETWEEN 12,000 AND 17,000 FT, THE A AUTOPILOT WAS ENGAGED AND IT IMMEDIATELY "PUMPED" THE YOKE ONCE, FELT BY EVERYONE AND THEN IT SEARCHED FOR A VERTICAL SPEED TO MAINTAIN, VARYING BY 2,000 FPM. IT WAS DISCONNECTED AND A 2ND ATTEMPT MADE WITH SAME RESULT B AUTOPILOT WAS ENGAGED AND IT OPERATED NORMALLY. ACFT GROUNDED. FCC "A" FAILS SELF TEST WITH MSG'S 22-11337, 22-11121, 22-11235. "A" CHANNEL AUTO TEST FAILS WITH MSG 22-11132. PERFORMED FIM 22-11, TASK 820 FCCS EXCHANGED. NO FAIL MSG'S A OR B. EXCHANGED FCC'S TO ORIGINAL POSITIONS. NO FAIL MSG'S ON SELF TEST. FCC "B" LRU TESTS GOOD. REF AMM 22-11-33, NR 35. REPLACED FCC A IAW AMM 22-11-33. ACCOMPLISHED FCC "A" LRU INTERFACE TEST AMM 22-11-35 NR 35 OPS NORMAL. ACCOMPLISHED LAND VERIFY AMM 22-11-00 GRP 49. OPS NORMAL. ACCOMPLISHED FCC/AT HGS SENSOR TEST SMM 34-36-00, OPS NORMAL. ACFT REMAINS CAT IIIA A/L & HGS QUAL STATUS SCREW IS IN CATIIIA A/L HGS POSITION.