As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PERFORMED AN AIR TURN BACK, DUE TO A LOSS OF PRESSURIZATION. EXPEDITED DESCENT NO MASKS DEPLOYMENT. MX FOUND A COMPRESSOR INLET CLAMP LOOSE AT THE RT ACM AND RE-SECURED IT. ALSO FOUND THE LT PRSOV INOPERATIVE AND REPLACED IT. PERFORMED HULL LEAK CHECK AND SINGLE PACK CONFIDENCE CHECK. CHECKED GOOD.