As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU PNEUMATICS SURGING. TRANSFERRED TO MEL 49-11-01-01. MDDR NR 139876 CAT "C" DUE DATE 31DEC20. MCC NOTIFIED. "M" FUNCTION C/W. REMOVED AND REPLACED APU SURGE VALVE, IAW AMM 49-53-01. OPERATIONS CHECK GOOD. THIS CLEARS MDDR NR 139876.