What was found
AIRCRAFT RETURNED TO PLATFORM DUE TO (MACH TRIM FAIL) AND (SPEED TRIM FAIL) LIGHTS TURNED ON. BREAKERS P18 AND P6 WERE CHECKED, BEING CORRECT. FIM 22-1 TASK 801 PROCEDURE AND FCCS TEST IN CDU WERE PERFORMED, DETECTING FAILURES CODES 22-11199 AND 22-11333. ADDITIONALLY, FIM 22-15, TASK 817, 22-16, TASK 834 AND 22-16, TASK 835 PROCEDURES WERE PERFORMED, DETECTING THAT FCC (A) FAILED. FCC WAS REPLACED IAW MM 22-11-33, TESTED CORRECT.