What was found
WHEN AIRCRAFT B-18308 CLIMBS TO FL256, NR 2 ENGINE THRUST REDUCED TO IDLE, AND MSG ENG 2 STALL, APPROXIMATELY 30 MINUTES AFTER, MSG ENG 2 FAIL, FLIGHT CREW PERFORM ENGINE SHUT DOWN PROCEDURE AND TURN BACK TO HND AIRPORT. GROUND INSPECTION DISCOVER PS3 TUBE BROKEN, BROKEN PS3 TUBE REPLACED, LEAKAGE TEST NORMAL. COMPLETE ENGINE STALL/ENGINE WINDMILLING CHECK, CHECK NORMAL. GROUND ENGINE RUN NORMAL. CHECK ENGINE QAR PARAMETER, CONFIRM PS3 PRESSURE SUDDEN DROP IS THE MAIN REASON FOR ENGINE THRUST REDUCE. REVIEW MAINTENANCE RECORD, NR 2 ENGINE COMPLETE SB 72-0546 MODIFICATION ON MAY 27, 2018 (ENGINE TSN/CSN: 39480/13570)