What was found
BOS-SYR - FLT 4776 - CREW NOTED THAT THE LEFT INTAKEO LIGHT ILLUMINATED WHEN SYSTEM WAS SELECTED ON. ATTEMPTS FAILED IN TRYING TO RESET THE SYSTEM PER THE CHECKLIST. AIRCRAFT RETURNED TO BOS AND LANDED WITHOUT INCIDENT. MAINTENANCE REPLACED THE DUCT PARTICLE SEPARATOR IN THE LEFT INTAKE SYSTEM. LEFT INTAKE HEAT SYSTEM WAS OPERATIONALLY CHECKED GOOD AND AIRCRAFT WAS RETURNED TO SERVICE. (M)