As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRFRAME VIBRATION INFLIGHT MORE NOTICEABLE IN REAR CABIN AREA. STARTED FL 280 MACH .79. ACCOMPLISHED MT 53-005 IAW TSM 05-50-00-810-801-A. NO NOTICEABLE PLAY IN RUDDER OR ELEVATORS. FOUND YELLOW HYDRAULIC BAY ACCESS PANEL 196BB LOOSE WITH PIECES OF SEAL MISSING. REPLACED SEAL PIECES, DOOR NOW TIGHT & DOES NOT RATTLE.