What was found
AIR TURNBACK/DECLARED EMERGENCY, 2 LOUD BANGS HEARD, ALONG WITH MODERATE TO SEVERE VIBRATIONS FELT FROM NR 2 ENGINE. NR 2 ENGINE FUEL FLOW ERRATIC. ALL OTHER INDICATIONS NORMAL. FLAME SEEN FROM NR 2 ENGINE EXHAUST. REMOVED AND REPLACED NR 2 EEC, T12 SENSOR, 5TH STAGE PNEUMATIC BLEED CHECK VALVE AND N2 SENSOR PER MM. DURING TEST FLIGHT FOR COMPRESSOR STALL, NR 2 ENGINE STALLED TWICE DURING CLIMB. REMOVED AND REPLACED NR 2 ENGINE PER MM.