As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMB-OUT THROUGH 20,000 FEET, ENCOUNTERED AIRCRAFT VIBRATION. IT APPEARED THE RIGHT INBOARD TRAILING EDGE HAD STARTED TO FLUTTER. ACCOMPLISHED AIRCRAFT VIBRATION CHECK. ADJUSTED THE RIGHT INBOARD AFT FLAP AND PERFORMED FLIGHT CONTROL SYSTEM CHECK. CHECKED OK.