What was found
WE RECEIVED A L COWL ANTI ICE DUCT MASTER WARNING IN CRUISE. PERFORMED QRH PROCEDURE EMERGENCY 12-4 WHICH INSTRUCTED AN IN FLIGHT SHUTDOWN. THE MSG PERSISTED. (FLIGHT 3161) REFERENCE AML 721053. REFERENCE AML 721095. T/S L COWL ANTI ICE DUCT WARNING MESSAGE IN REF. TO FIM 36-21-09. PERFORMED LEAK CHECK OF THE LT SIDE COWL A/I DUCTING IN REF. TO AMM 30-20-00. NO LEAKS NOTED AT THIS TIME. PERFORMED VISUAL INSPECTION OF ALL LH DUCTS, COUPLINGS, JOINTS, AND LOOPS. WITH NO DEFECTS NOTED AT THIS TIME. REF AMM 36-21-00. PERFORMED OPERATIONAL TEST OF THE LT COWL A/I VALVE IN REF. TO AMM 30-22-01. OPS CHECKS GOOD AT THIS TIME. SUSPECT BAD LEAK DETECTION TRANSDUCER. REMOVED AND REPLACED LEAK DETECTION TRANSDUCER REF. EAML 721053 FOR R&R INFORMATION. FOR T/S PURPOSES REMOVED AND REPLACED THE ALIC REF. EAML 721095 FOR R&R INFORMATION.