As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ACFT EXPERIENCED A WINGTIP VIBRATION OF APPROX 24" AMPLITUDE AND 3-PER-SECOND FREQUENCY AT BOTH WINGTIPS. THIS EVENT LASTED FOR A DURATION OF APPROX 15-20 SECONDS DURING DESCENT THROUGH FL330 AT MACH 0.78 AND RELATIVELY LIGHT ACFT LOAD. THIS EVENT WAS INDUCED BY PENETRATION OF LIGHT TURBULENCE. REDUCTION OF POWER AND DEPLOYMENT OF AIRBRAKES WITH ATTENDANT DECELERATION HALTED THE EVENT. THIS ACFT IS EQUIPPED WITH BLENDED WINGLETS (STC ST01411SE).