What was found
LEFT DUCT PRESSURE 4 PSI RIGHT DUCT PRESSURE 35 PSI FOR FIRST 50 MIN OF FLY, DUCT PRESSURE NORMAL FOR REMAINDER AT 35 PSI (VERBAL FROM PILOTS: 39,000 FT ALT FAULT OCCURRED). GROUNDED - YES. REF B737-900 FIM 36-10 TASK 804 DUCT PRESS LOW, #1 ENG BLEED AIR SOURCE. REF FIM 36-10 TASK 813 ENG BLEED AIR DISTRIBUTION SYS LEAK CK, REF FIM 36-10 TASK 812, PNEU T/C USING PNEU TESTER. SUPPLIED AIR TO PRECOOL VALVE, PRSOV & BLEED AIR REG NO DEFECTS NOTED. LEAK DETECTED ON PRSOV CONT PRESS SENSE LINE. R/R PRESS SENSE LINE REF B737-900 AMM 36-11-04. NO LEAK DETECTED. PERF HI ENG POWER RUN FOR ENG BLEED AIR CROSSOVER TEST. WITH BOTH ENG AT IDLE BLEED 1 AND OFF, APU BLEED OFF, BOTH PACKS OFF AND ISOL VALVE CLOSED, #1 ENG BAR FAILS TO OPEN/CLOSE (INTERMITENTLY). R/R #1 ENG BAR REF AMM 36-11-03/401. LEAK/INSTL TEST GOOD. ACCOMP CROSSOVER CHECK PER AMM 36-11-00-710-801 OPS CHECKED GOOD.