As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: AN EMERGENCY WAS DECLARED AND THE AIRCRAFT RETURNED TO PHL DUE TO THE FLIGHT CREW REPORTING THAT AFTER TAKEOFF ENGINE 1 HAD HIGH VIBRATIONS UP TO 9.9 ON N1 AND A BURNING SMELL WAS NOTED AT THE SAME TIME - THE BURNING SMELL CEASED AFTER BLEED 1 SHUT OFF - THE AIRCRAFT LANDED SAFELY AT PHL WITHOUT FURTHER INCIDENT. (OPEN)