As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LOW FREQUENCY VIBRATION CAN BE HEARD AND FELT ON FLOOR PANELS. BEGINS AT 320 KTS, BELOW 320 KTS VIBRATION CEASES. TIGHTENED LOOSE FLAP TO BODY FAIRING ON LEFT FLAP ASSY AND ADJUSTED NOSE LANDING GEAR DOOR PRELOAD PER DC9 MM 32-22-01. INSPECTED TABS AND ANTENNA'S FOR SECURITY. NO DEFECTS NOTED.