What was found
PBI FLT1733 - EN ROUTE FROM DCA TO PBI, DURING CRUISE, CREW REPORTED THE FIRST OFFICER'S R1 WINDSHIELD BEGAN TO ARC. THE R1 WINDOW HEAT WAS SELECTED OFF. WITHIN A FEW MINUTES, THE WINDOW STARTED TO CRACK IN MULTIPLE PLACES RESTRICTING VISIBILITY. FLIGHT LANDED WITHOUT FURTHER INCIDENT. MAINTENANCE REMOVED AND REPLACED THE FIRST OFFICER'S R1 WINDSHIELD PER MM 56-11-11. ALSO, REMOVED AND REPLACED THE R1 WINDOW HEAT CONTROL UNIT AS PRECAUTIONARY. OPERATIONAL CHECK GOOD.