What was found
R PSCK OVERTEMP CAUTION MESSAGE. SMOKE AND ELECTRICAL BURING SMELL IN CENTER CABIN IMMEDIATELY AFTER DEPARTURE, RETURNED TO MDW. DEFERRED RT PACK PER MEL 21-51-1A. VERIFIED RAM AIR SOV OPERATIONAL, NO SMELL PRESENT, MXC NOTIFIED #53431, ENTERED INTO MM02, PLACARD INSTALLED.