As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
VIBRATIONS FROM FRONT OF AIRCRAFT OCCURRED WHEN LANDING GEAR RETRACTED ON TAKEOFF. VIBRATIONS CEASED WHEN GEAR WAS EXTENDED, BUT RESUMED WHEN GEAR WAS RETRACTED. AIRCRAFT RETURNED TO GEG. INSPECTED AND VERIFIED PROPER SECURITY OF NOSE LANDING GEAR DOORS. NO DEFECTS NOTED.