What was found
WHILE AT 22,000 FEET AND IN CRUISE FLIGHT, THE PILOT TURNED ON WINDSHIELD HEAT AND IMMEDIATELY THE WINDSHIELD SHATTERED. BOTH PPG AND RAYTHEON ADMIT THIS IS A COMMON OCCURRENCE. THE EXACT DATE WHEN THE DISCREPANT WINDSHIELD WAS INSTALLED IS NOT CLEAR. REPLACED WITH NEW UNIT, CORRECTED PROBLEM. CORE ROUTED TO SCRAP. DATE: 4-23-98.