What was found
DURING CRUISE FLIGHT, AIR MANIFOLD 2 FAIL, LEVEL ONE AIR SYSTEM 2 OFF. MANIFOLD RED LIGHT ON OVERHEAD MEL, RELEASED FOR SERVICE PER MEL/CDL: 36-23-01-02. NR 2 MANIFOLD FAIL DETECTION LOOP INOPERATIVE. TROUBLESHOT PER FIM 36-23-01, 36-23-04, AND 36-23-09. CLEARED AIU1 MX PREFLIGHT AND RAN AIR SYSTEM TEST. TEST FAILED AND AIU 1 CURRENT FAULT SHOWED "314211 NO LOOP 2 INPUT RECEIVED DURING PREFLT TEST-P (FIM FAULT CODE 36-23-09)." R & R NR 2 MANIFOLD FAILURE DETECTION CONTROLLER M/M 36-23-01-4. OPS CHECK SYSTEM DURING ENGINE RUN PER MD10 JRH, NO PROBLEMS NOTED. AIRCRAFT OK FOR SERVICE.