What was found
AIRCRAFT NOT GROUNDED: PILOT REPORTS CLIMBING THROUGH FL280, CAPTAINS WINDOW AREA BEGAN A LOUD SQUEALING NOISE. LEVELED OFF AT FL330 AND NOISE WAS SO LOUD THE COCKPIT CREW HAD TO YELL TO HEAR EACH OTHER, NOISE COULD BE HEARD IN THE FORWARD GALLEY, DESCENT TO FL250 WAS NO HELP. CLIMBED AGAIN TO FL330 AND THE NOISE SLOWLY WENT AWAY. MAINTENANCE INSPECTED AND CLEANED WINDOW SEALS, NO DAMAGE OF SEAL NOTED. INSTALLED INSULATING COMPOUND AND LEAK CHECKED NORMAL. ACCOMPLISHEDWINDOW CONFIDENCE CHECK IAW AMM 05-51-24-720-801.