What was found
(CAN) ON OCT. 27, 2006 A/C 201 EXPERIENCED A CRACKED NR 4 LT EYEBROW WINDOW. THE A/C CONTINUED TO ITS DESTINATION WITHOUT ANY FURTHER EVENTS. THE NR 4 WINDOW WAS REPLACED. BOEING IS AWARE OF THIS IN SERVICE ISSUE AND HAS INITIATED SERVICE RELATED PROBLEM (SRP) 56-0018. BOEING HAS ALSO ISSUED SERVICE BULLETIN 737-56-1017 TO PROVIDE 737NG OPERATORS WITH AN OPTION TO REPLACE THENR 4 AND 5 WINDOWS WITH STRUCTURAL PLUGS. WESTJET IS PLANNING ON INCORPORATING THIS SERVICE BULLETIN. (TC# 20061114009)