As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
VIB INDICATION FOR BOTH ENGINES WENT OFF THE SCALE WITH A VIOLENT SHAKING OF THE AIRFRAME AT 18,000 FEET. (FLT 6479) RAN BOTH ENGINES AT VARIOUS POWER SETTINGS. OPERATED BOTH COWL ANTI-ICE VALVES SEVERAL TIMES. INSPECTED FAN BLADES AND TURBINE BLADES, NO DAMAGE NOTED. NO ABNORMAL VIBES NOTED.