What was found
CLT - FLT 1635 - AIRCRAFT DEVELOPED AN AIRFRAME VIBRATION AT LEVEL OFF AT FL 260. AFTER CHECKING THAT ALL AIRCRAFT SYSTEMS WERE NORMAL, THE CAPTAIN DECIDED TO DIVERT TO CLT. THE CAPTAIN BELIEVED THERE WAS AN ACCESS DOOR OPEN. THE FLIGHT LANDED WITH NO FURTHER INCIDENT. MAINTENANCE FOUND AND CONFIRMED THE EXTERNAL POWER ACCESS DOOR WAS OPEN CAUSING VIBRATIONS. DOOR WAS CHECKED FOR DEFECTS AND FOUND OK. SECURED DOOR. NO OTHER DEFECTS FOUND. (X)