As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LOUD VIBRATION AFTER TAKEOFF. VIBRATION INCREASED WITH SPEED AND DECREASED AT LOWER SPEEDS. RETURNED TO DEPARTURE AIRPORT. PERFORMED VIBRATION CONDITIONAL INSPECTION. FOUND NLG DOORS ON GRAVEL SKI EQUIPPED AIRCRAFT TO BE BINDING ON EACH OTHER. ADJUSTED PER AMM 32-22-12. AIRCRAFT RELEASED AN OPERATIONAL CHECK FLIGHT NORMAL. NO REPORT OF VIBRATION ON SUBSEQUENT FLIGHTS.