As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
BOS-PHL - FLT 4773 - DURING CLIMB-OUT, CREW NOTED A BURNING SMELL IN THE COCKPIT. THEY SHUTDOWN THE RIGHT BLEED SYSTEM AND THE SMELL WENT AWAY. A/C DIVERTED BACK TO BOS AND LANDED WITHOUT INCIDENT. MAINTENANCE REMOVED AND REPLACED THE RT ACM AND PERFORMED ALL REQUIRED CHECKS SATISFACTORILY. AIRCRAFT RETURNED TO SERVICE. (M)