What was found
ENG ANTI-ICE COWL VALVE LIGHT IS ON AT LESS THAN 28000 FEET PERFORMED FIM 30-21 TASK 810, NO RELATED FAULT IN OMF. TS FIM UP TO STEP B.(3). DURING CHECK OF COWL THERMAL ANTI-ICE VALVE, FOUND PRSOV OPERATING INCORRECTLY, WILL NOT STAY IN OPEN POSITION WHEN BLEED AIR SYSTEM IS PRESSURIZED BY APU REF SUBTASK ADD EMP:U393575 36-00-00-860-230 OF AMM 36-00-00-860-805. SUSPECT BAD PRSOV, PRSOV ON AOG, LOCK OUT TOOL BOXES ARE IN THE FORWARD CARGO PIT. VALVE, SHUTOFF, OFF 42-3611-9-0002 1117 ON 42-3611-9-0002 2923 VALVE, SHUTOFF, OFF 42-3611-9-0002 1117 ON 0000 R/R ENG #2 PRSOV PER AMM 36-11-04. ALL OPS CHECKS GOOD AT THIS TIME. PARTS USED: 42-3611-9-0002,QTY :1 ROTABLE PARTS CHANGE WAS INDICATED - TT # 1527933 SN OFF 1117.