As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PHL - FLT 1447 - EN ROUTE FROM PHL TO ATL, AT FL270, CAPTAIN REPORTED VIA ACARS THE L1 WINDSHIELD CRACKED. FLIGHT RETURNED TO FIELD AT PHL AND LANDED WITHOUT FURTHER INCIDENT. NO PRESSURIZATION PROBLEMS WERE ENCOUNTERED AND NO EMERGENCY WAS DECLARED. MAINTENANCE REMOVED AND REPLACED THE L1 WINDSHIELD. OPERATIONAL CHECK AND LEAK CHECK GOOD.