As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
NR 1 ENGINE IFSD AT FL300. ENGINE STALL REPORTED WITH SURGING. FLAMES OBSERVED BY FA''S FROM FRONT AND REAR OF ENGINE. DIVERTED BOS. *S/D* ENGINE WAS REMOVED. FOUND AND REPLACED FAILED INTERMEDIATE PRESSURE CHECK VALVE IN PNEUMATIC SYSTEM LOCATED AT 11 O''CLOCK ON 8TH STAGE DUCT OF ENGINE HIGH PRESSURE COMPRESSOR. THE CHECK VALVE WAS STUCK IN THE OPEN POSITION.