What was found
L 10TH DUCT WARNING MESSAGE ON CLIMB AT 15000FT. DID THE QRH PROCEDURE, DIRECTED TO GET LEFT ENGINE TO IDLE. DECLARED EMERGENCY AND DID A SINGLE ENGINE LANDING WITH RIGHT ENGINE. (FLIGHT 5541 FILED OPEN)FOUND LEAK COMING FROM LH 10TH STAGE PRSOV FLANGE CRACK FACING LOOPS A50WK AND A51WK. REPLACED LEFT PRESSURE REGULATING SHUT-OFF VALVE ASSY IN REF TO CRJ200 AMM 21-51-43. COMPLIED WITH OPERATIONAL CHECK OF LEFT PRSOV IN REF TO AMM TASK 21-51-43-710-801). ALL INDICATIONS NORMAL. OPS CHECK AND LEAK CHECK GOOD.