What was found
DURING FLIGHT 3116, LT INTAKE HEAT INOP. AIR TURNBACK TO DTW. MAINTENANCE OHMED OUT INTAKE, UPPER DUCT, EXHAUST NOZZLE, BIR CATCH ALL CHECKS GOOD. SUSPECT BAD DE-ICE CONTROL. MAINTENANCE REPLACED DE-ICE CONTROL, GROUND RUN A/C FOR 30 MINUTES ALL WORK DONE IAW SAAB 340 MM, ALL CHECKS GO.