What was found
CREW REPORTED A RUBBERY BURNING ODOR DURING TAKEOFF, PACK NOT COOLING , FELT VIBRATION UNDER FLOOR. ACFT RETURNED TO DEPARTURE, & LANDED WITHOUT INCIDENT. MX INSPECTED AND FOUND NR 1 ACM TO BE SEIZED. R & R THE NR 1 ACM, OPS TESTED WITH NO DEFECTS, AND THE ACFT WAS APPROVED FOR RETURN TO SERVICE.