As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIR TURN BACK, IMMEDIATELY AFTER GEAR RETRACTION, NR 1 HYDRAULIC SYSTEM QUANTITY WENT TO ZERO AND NR 1 HYDRAULICS SYSTEM PRESSURE ALSO WENT OT ZERO WITHING 30 SECONDS. FOUND LEFT CCA FILTER HOUSING CRACKED. REMOVED AND REPLACED LEFT CCA IAW AMM 27-11-08. (M)