What was found
DURING CLIMB, UNABLE TO MAINTAIN PRESSURIZATION WITH FOUR T/C'S OPERATING AT 24,000 FT. CABIN DIFFERENTIAL KEPT CLIMBING, RETURNED TO JFK. FOUND LEFT SIDE TURBO COMPRESSOR HOT AIR DUCT CLAMP LOOSE BY BULKHEAD IN UNPRESSURIZED AREA. RETIGHTENED CLAMP, PRESSURIZED AIRCRAFT TO 8.6 AND NO LEAK NOTED.