What was found
FLT#679, JFK-MKE. (AIRCRAFT PERFORMED AN AIR TURN BACK TO JFK) 'IMMEDIATELY AFTER T/O L BLEED FAIL. WHILE RUNNING ECL EXPERIENCED STRONG A/C VIBRATION WITH A FUME SMELL (EXHAUST SMELL) AFTER LANDING - CABIN INSTANTLY GOT HOT, SLIGHT SMELL, THEN R PACK FAIL (OVERHEAT); PERFORMED BAS IBIT ON IASCIA CH A AND B. NO FAULTS PRESENT, TEST PASSED. IDLE ENG RUN ACCOMPLISHED REF AMP TASK 72-21-01. ISOLATED TO PACK 1 WITH ENG BLEED. NO FAULTS PRESENT. A/C OK FOR SVC.'