As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON CLIMB THRU 15,000 FT, A LOUD SQUEAL WAS HEARD FROM CAPT'S FORWARD WINDOW LOWER LT CORNER. SQUEAL STAYED AT CRUISE, 5.4 PSI ON DIFFERENTCIAL & CABIN ALT OF 6,000. ON DESCENT SQUEAL WENT AWAY AT 2500 CABIN ALTTITUDE. RETURNED TO FIELD. LANDING UNEVENTFUL. TORQUE CHECK OF WINDOW SCREWS OK. REPLACED EMERGENCY CREW HATCH. PRESSUREIZED AND DE-PRESSUREIZED IAW AMM TASK 21-00-00-863-801 AND 21-00-00-863-802 TO 3.5 PSI DIFF ON GROUND, NO DEFECTS NOTED, NO SQUEALS NOTICED. RETURNED TO SERVICE.