As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: ON INITIAL CLIMB OUT, WHEN PASSING FL260 AND DOING 335 KNOTS, THERE WAS AN EXTREME VIBRATION FELT THROUGHOUT THE ENTIRE AIRCRAFT. ENGINE VIBRATIONS WERE LOW AND NORMAL. FLIGHT CONTROL PAGE SHOWED NO FLIGHT CONTROLS OUT OF NORMAL RANGE. WHEEL PAGE SHOWED NOGEAR DOORS OPEN. WE SLOWED OUR AIRSPEED TO M.75 AND AS WE LEVELED AT FL300 THE VIBRATION STOPPED. WE SUBSEQUENTLY INCREASED OURSPEED TO M.77 AND THE VIBRATION DID NOT RETURN. (OPEN)