As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) FLIGHT DEPARTED AND BEGAN TO EXPERIENCE AN AIRFRAME VIBRATION, CREW DECLARED A PAN PAN AND DIVERTED BACK. EMERGENCY CREWS WERE ON STAND BY ON LANDING AND ONCE ON GROUND WERE WAIVED OFF BY FLIGHT. R & R ELAC NR 1 IAW AMM 27-93-24 PB401. PERFORMED OPS TEST IAW AMM 27-93-00-710-001, PASSED. PERFORMED LAND CATIII CAPABILITY TEST IAW AMM 22-97-00-710-001. TEST PASSED.