What was found
AT FL 350, HAD A LEVEL 3 AIR MANIFOLD 3 FAILURE. RAN QRH, ALERT WENT AWAY. DECLARED AN EMERGENCY AND DIVERTED TO NEAREST SUITABLE AIRPORT. CHECKED MANIFOLD FAILURE INDICATORS IN CAC AND FOUND RT MANIFOLD PRESSURE SWITCH FAULTING IAW AMM 36-23-03-4-0, 36-00-01-5-0, 36-00-02-5-0. REMOVED AND REPLACED THE RT MANIFOLD PRESSURE SWITCH IAW AMM 36-23-03-4. CARRIED OUT PRESSURE DECAY TEST WITH APU IAW AMM 36-00-01-5. DECAY TEST PASSED. LEAK CHECKED DUCTING FROM CAC TO INBD SIDE OF NR 3 ENGINE. NO LEAKS FOUND. CARRIED OUT ENGINE RUN UP IAW JRA 5 & 6, FUEL BURN INDICATED DURING RUN UP WAS 240, FUEL ON BOARD WENT FROM 50,400 TO 50,200 LBS. CARRIED OUT A DECAY TEST WITH ENGINES IAW AMM 36-00-02-5. ALL TESTS PASSED. CHECKED MANIFOLD FAILURE INDICATORS IN CAC. AFTER ENGINE RUNS, NO FAULTS INDICATED. ACFT OK FOR SERVICE.