As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
BOS - FLT 6447 - DURING TAXI OUT, CREW NOTED INTERMITTENT ODOR. SIMILAR TO BLEED OR FAN BURNING ODOR. F/A REPORTED SCRATCHING NOISE NEAR WING ROOT. AIRCRAFT RETURNED TO GATE WERE MAINTENANCE DEFERRED THE RT RECIRC FAN ASSY. AIRCRAFT RETURNED TO SERVICE. (M)