What was found
(CAN) IN CRUISE FLIGHT, THE NR 1 ENGINE ADAPTER CAUTION LIGHT CAME ON AND THE CREW HEARD THE 115 V CB POP, LOCATED ON THE PANEL BEHIND THE CO-PILOT. 1 CB RESET WAS ATTEMPTED ONCE ON THE GROUND AND IT POPPED AGAIN. MAINTENANCE INVESTIGATION FOUND THE LT INTAKE LIP HEATER ELEMENT SHORTED AND BURNED OUT WITH A STRONG BURNED ELECTRICAL ODOR. THE LT LIP HEATER WAS REPLACED AND THE ACFT RETURNED TO SERVICE. INTAKE LIP HEATER PN 4100S028-05, SN 2316. ENGINE PN PW150A, SN FA0839, ENGINE TSN 4023, CSN 2831. ACFT TSN 4006, CSN 2814.