As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AT T/O CREW REPORTED LEFT DUCT PSI FLUX ALONG WITH L-2 DOOR AREA HAVING VIBRATION AND VIBRATION WAS FELT IN CONTROL COLUMN ROLL MODE. RETURNED TO JFK FOR REPAIRS. INSPECTED LEFT ENGINE FOR BIRD STRIKE. BOROSCOPED AND VIBE SURVEYED. REPLACED PRSOV FOR HISTORY OF BLEED FLUX.