What was found
LOUD SQUEAL, CLIMBING THROUGH 25,000 FT. LOUD SOUND CONTINUED UNTIL DESCENDING THROUGH 16,000 FT, THE FLIGHT DECLARED AN EMERGENCY AND LANDED WITHOUT FURTHER INCIDENT. AIRCRAFT WAS GROUNDED. MAINTENANCE FOUND SCREWS LOOSE ON THE WINDOW FRAME. TORQUED THE WINDSCREEN IAW AMM 56-11-11-400-801. LEAK AND PRESSURE TESTED IAW AMM 05-51-91-795-801, AND ACCOMPLISHED MCM 05-96-19. NO SQUEALS OR LEAKS NOTED.