As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
RETURNED TO THE FIELD AT ORD DUE TO LEFT ENGINE BLEED FAILURE. *S/D* LT ENGINE HIGH STAGE CONTROLLER WAS FOUND WITH A LOOSE CONNECTOR. CONNECTOR WAS SECURED AND HIGH STAGE MUSCLE LINES WERE REPLACED AS A PRECAUTION. NO FURTHER PROBLEMS HAVE OCCURRED SINCE THE CORRECTIVE ACTIONS.