What was found
****PART DEFECT/LOCAL: TAIL EQUIP BAY-VALVE STUCK CLOSED****PILOT REPORTED UNABLE TO START LT ENGINE. NO BLEED AIR PRESSURE AVAILABLE. TROUBLESHOT SYSTEM, FOUND POWER TO ISOLATION VALVE, BUT NO MOVEMENT OF VALVE. FOUND VALVE TO BE STUCK IN CLOSED POSITION. REMOVED FAULTY VALVE, INSTALLED REPAIRED VALVE OF SAME PART NUMBER. OPERATIONAL AND LEAK CHECK GOOD. ALL WORK PERFORMED IAW GAC GIV MM, CH 36-12-00 AND CMP S61065. OLD VALVE SEAT TO GAC FOR EVALUATION. AIRCRAFT RETURNED TO SERVICE. LANDINGS: 1,511. (X)