What was found
AFTER ENGINE START RUDDER PWR OFF ALERT ILLUMINATED WITH BOTH ENGINES RUNNING, AUX AND HYD TRANS PUMPS ON. CHECKED RUDDER OPERATION WHICH APPEARED NORMAL. PERFORMED FIM 27-20-00-810, NO DEFAULT NOTED OK FOR SERVICE, 2ND BTB: SWAP TO ACFT 476, ACFT 486. REMOVED AND REPLACED RUDDER CONTROL MANUAL SWT. OPS CHECK OK ACFT RELEASE FOR SERVICE.