What was found
FLT 1250 - GEG-PDX - UNABLE TO CONTROL CABIN PRESSURE. THE AIRCRAFT WOULD MAINTAIN 5 PSID AND THE CABIN CLIMBED TO 15,000 FT. THE CREW DESCENDED THE AIRCRAFT TO A LOWER ALTITUDE AND WENT ON OXYGEN. THE AIRCRAFT CONTINUED TO PDX AND LANDED WITHOUT FURTHER DIFFICULTIES. CLEANED BOTH LEFT AND RIGHT OUTFLOW VALVE. FURTHER TROUBLESHOOTING FOUND TWO EACH B-NUTS LOOSE BEHIND THE F/E PANEL. TIGHTENED THE SAME AND PERFORMED AND OPERATIONAL CHECK AND ALL INDICATIONS WERE FOUND TO BE NORMAL. (M)