As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
STRONG VIBRATION FELT AND HEARD OVER 280KTS. SOUND REDUCED AS WE SLOWED AND INCREASED AS WE SPED UP. SLOWED TO 250KTS REMAINDER OF FLIGHT. VIBRATION STRONG ENOUGH TO BE FELT THROUGH SEATS(<P>INSPECTED A/C PER B737 AMM 05-51-67. FOUND EXTERNAL POWER DOOR OPEN. INSPECTED DOOR. OK FOR SERVICE. NO OTHER DEFECTS FOUND. SECURED EXTERNAL POWER DOOR CLOSED.</P>)