As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTED THAT THE LANDING GEAR WOULDN'T RETRACT AFTER TAKEOFF FROM PHL, DECLARED AN EMERGENCY AND RETURNED TO FIELD AT PHL AND LANDED WITHOUT INCIDENT. MAINTENANCE TROUBLESHOT AND PERFORMED A GEAR SWING PER EMB AMM AND OPS CHECK GOOD. A/C WAS THEN RELEASED BACK INTO SERVICE.