As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
INSPECTION TYPE:N/A AT APPROX 3000 FT CREW NOTICED SMOKE IN COCKPIT DID AN AIR TURNBACK TO DEC. REMOVED AND REPLACED THE A-SYSTEM AIR PRESUURE REGULATOR IAW M/M 2912. FOUND EVIDENCE OF HYDRAULIC FLUID IN RES AIR PRESSURE CHECK VALVE ASSY RNR ALL 3 CHECK VALVES PERFORMED LEAK CK RAN ALL ENGINES WITH 2 PACKS, NO FAULTS NOTED RNR WATER SEPARATOR BAGS PRECAUTIONARY.