As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
IN FLIGHT ABOVE 200 KTS THERE IS A RUMBLING VIBRATION THAT VIBRATES THE WHOLE AIRPLANE. IT CHANGES PITCH OR SEVERITY WITH INCREASE IN SPEED, 250 KTS IS THE SPEED THAT IT IS MOST PRONOUNCED. FOUND ACCESS PANEL ON LOWER LT STUB WING NR 313AL TO BE OVERLAPPING PANEL NR 313AC AND OIL CANNING. TRIMMED PANEL NR 313AL IAW SRM OK 51-00-03 AND MM CH 53-30-00. INSTALLED PANEL NR 313AL NO OIL CANNING PRESENT.