As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CRUISE PHASE OF FLIGHT, THE AIRCRAFT WAS TURNED BACK DUE TO THE LH ENGINE AIR BLEED FAULT. THE AIRCRAFT LANDED WITH NO INCIDENT NOR WEIGHT EXCEEDANCE. AT MAINTENANCE, THE BLEED PRESSURE REGULATOR VALVE AND ITS SOLENOID ON LH ENGINE WERE REPLACED PER TROUBLESHOOTING AND MAINTENANCE MANUAL AND PERFORMED ALL REQUIRED FUNCTIONAL TEST WITH NOT FAULTS. AFTER THE DESCRIBED CORRECTIVE ACTIONS WERE PERFORMED, THE AIRCRAFT WAS RETURNED TO SERVICE.