As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LEFT PACK SURGING CAUSING LEFT ENGINE PARAMETER FLUCTUATION. RESET PACK ONCE PER FLIGHT MANUAL PROCEDURE 2.20.14 INDICATION RETURNED TO NORMAL BRIEFLY, THEN FAILED AGAIN SHORTLY THEREAFTER. UPPER PACK CONTROL VALVE FAIL INTERNALLY WITH THE VALVE CLOSED. NOTICED WHEN DOING LEAK CHECK ON UPPER FCV THAT THE LOWER FCV WAS FLUCTUATING OR SURGING. NEED MORE TIME TO T-S. REMOVED AND REPLACED LOWER FLOW CONTROL VALVE. OPS CHECK AND LEAK CHECK GOOD AT THIS TIME.