RPTR EXPERIENCES CRACKED WINDSHIELD.

Narrative

ENRTE TO DCA THE CAPT'S FRONT WINDSHIELD 'EXPLODED AND CRACKED INTO A SPIDER WEB LIKE PATTERN' THAT AFFECTED THE ENTIRE WINDSHIELD. (THERE WAS NO EVIDENCE OF A BIRD STRIKE.) WE COMPLETED THE CRACKED WINDSHIELD CHKLIST (WHICH CALLS FOR A MAX SPD OF 180 KIAS AND REDUCED CABIN PRESSURE DIFFERENTIAL TO 2.5-3.0 PSI) AND DSNDED TO 6000 FT. WE DECLARED AN EMER (THE WINDSHIELD CONTINUED TO POP AND CRACK) AND ASKED TO DIVERT TO PHL. THE FO (PF) FLEW AN ILS TO RWY 17 AND LANDED WITHOUT FURTHER INCIDENT. DISCUSSIONS LATER WITH MAINT CONFIRMED OUR RPT TO THE COMPANY THAT THE INNER PANE HAD CRACKED IN SPOTS NEAR THE CTR POST; L SIDE POST; AND DIRECTLY IN FRONT OF THE CAPT'S VIEW. ALSO; THE OUTER PANE HAD CRACKED OVER THE ENTIRE WINDSHIELD. THIS IS NOT THE FIRST INCIDENT WHERE A FRONT WINDSHIELD HAS SEVERELY CRACKED ON A DEHAVILLAND DHC-8. RECENTLY THE COMPANY HAS CHANGED VENDORS ON WINDSHIELDS TO SAVE MONEY. THE MATTER IS CURRENTLY UNDER INVESTIGATION BY THE COMPANY AND A PLT GROUP'S SAFETY AND ENGINEERING DEPT. I DO RECOMMEND THAT; DUE TO THE QUICK ACTIONS REQUIRED BY THE CREW; TO PREVENT INJURY OR DEATH TO THE PLTS BECAUSE OF A POSSIBLE TOTAL STRUCTURAL FAILURE OF THE WINDSHIELD; THAT THE CHKLIST BECOME A CRITICAL ACTION PROC OR 'BOXED ITEM' TO MEMORIZE. KNOWING WHAT TO DO (SLOW BELOW 180 KTS AND REDUCE CABIN DIFFERENTIAL TO 2.5-3.0 PSI) AND DOING IT IN A TIMELY MANNER COULD PREVENT TOTAL FAILURE OF A WINDSHIELD. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: ANALYST ASKED THE RPTR IF THE WINDSHIELD IS GLASS. THE RPTR STATED YES AND 3 LAYERS; OUTER; MIDDLE AND INNER PANES. THE MIDDLE IS STRUCTURAL. THE COMPANY MECH AND RPTR AGREE THE INNER AS WELL AS THE MIDDLE AND OUTER WERE CRACKED. THE COMPANY MGMNT SAYS THE INNER WAS NOT CRACKED. THE RPTR WAS NOT SURE IF IT IS STILL A PROB. HE STATED THAT HE DID NOT KNOW WHO THE VENDOR IS OR IF THE COMPANY IS STILL USING THIS VENDOR. WITHIN THE LAST YR ANOTHER CAPT WITH THIS AIRLINE EXPERIENCED SIMILAR CRACKING. THE FIRST THING THE RPTR DID WHEN THE WINDSHIELD CRACKED WAS TURN THE WINDSHIELD HEAT FROM 'ON' TO 'NORMAL' TO 'WARM UP.' THEN HE SLOWED THE ACFT AND ESTABLISHED THE PROPER PRESSURE DIFFERENTIAL FOR THE PROC. THE RPTR BELIEVES THAT THE PROB WAS VERY LIKELY WINDSHIELD HEAT. THERE WERE NO PREVIOUS DELIMITATION OR WRITE-UPS. IN FACT; THE RPTR HAD THIS ACFT ON THE FIRST FLT OF THE PREVIOUS DAY AND PREFLT CHK REQUIRED CHKING ALL 3 PHASES OF THE WINDSHIELD HEAT AND ITS ENTIRE OP. THERE WAS NOTHING WRONG AT THAT TIME WITH THE SYS.