What was found
EMERGENCY DECLARED - WHILE IN CRUISE, NAV MODE FAILED SEVERAL TIMES REVERTING TO HDG MODE. T/S IN REF TO TSM 2-10-00 AND AMM 22-40-00-05, FOUND FCU FAULTED, REMOVED AND REPLACED FCU IN REF TO AMM 22-15-12-04 AND TESTED IN REF TO 22-00-00 P BLOCK 501 AND 22-40-00 P BLOCK 501 PARA 1.B.