What was found
RUDDER RATIO EICAS MESSAGE AFTER TAKEOFF. QRH CHECKLIST ACCOMPLISHED. NOTIFIED GOC. NO ADVERSE HANDLING CHARACTERISTICS NOTED IN FLIGHT OR ON LANDING. EMERGENCY DECLARED. SHGN 29APR22 17:31 OAK FOLLOWING 757 FIM 27-21 FAULT TREE 809. AT STEP 21 FOUND HYD PRESS SWITCH S27 WITH DISCOLORATION AT PIN 3. REMOVED AND REPLACED SWITCH S27 PRECAUTIONARY REF AMM 29-11-17-4. LEAK AND OPS NORMAL. RUDDER SYS TEST NORMAL REF AMM 27-21-00-5. STILL T/S RUDDER RATIO SYS. SHGN 29APR22 18:02 OAK REF TSI 27-21/7703 AND 27-21/7702. ALL TEST AND BITE CHECKS PASS NORMAL. CAN NOT DUPLICATE PROBLEM. REMOVED AND REPLACED LEFT RUDDER RATIO CHANGER MODULE REF MM 27-09-00-2 AND PERFORMED ADJUSTMENT AND TEST REF MM 27-21-00-5. ALL TEST PASSED. REF TSI 27-21/7702 SUGGEST CHANGING RIGHT RUDDER RATIOCHANGER MODULE AS WELL. ONLY 1 IN STOCK OAK. PLACED ANOTHER AOG. REMOVED AND REPLACED RIGHT RUDDER RATIO CHANGER MODULE REF MM 27-09-00-2 AND PERFORMED ADJUSTMENT AND TEST REF MM 27-21-00-5. ALL TEST PASSED. ACFT OK TO CONT SERVICE.