What was found
ACFT WOULD NOT PRESSURIZE ON TAKEOFF. RETURNED TO FIELD. LANDING UNEVENTFUL. FOUND CLAMP CONNECTING COMPRESSOR OUTLET DUCT AND COMPRESSOR OUTLET CROSSOVER DUCT FROM THE LT AIR CONDITIONING PACK CAME LOOSE AND LEAKING AIR. R & R LT COMPRESSOR OUTLET DUCT AND COMPRESSOR OUTLET CROSSOVER DUCT, REF AMM 21-51-21-000-801/400-801. PRESSURIZED THE ACFT IAW 21-00-00-863-801. PRESSURIZATION CHECK GOOD. ACM AIRFLOW CHECKS GOOD. NO FURTHER DEFECTS NOTED. RETURNED TO SERVICE.