What was found
ON THE FLIGHT, DURING CLIMB OUT EXPERIENCED MODERATE VIBRATIONS IN THE ACFT THAT BEGAN TO INTENSIFY. ALL ENG PARAMETERS & INDICATIONS WERE NORMAL. THE CAPTAIN DISCONNECTED THE AUTOPILOT FOR THE REMAINDER OF THE FLIGHT & NOTICED NO ABNORMAL VIBRATIONS IN THE FLIGHT CONTROLS. THE CAPTAIN ELECTED TO RETURN & NOT KNOWING THE SOURCE OF THE VIBRATIONS, DECLARED AN EMER & LANDED WITHOUT ISSUE. THE VIBRATIONS PERSISTED UNTIL LANDING & SHUTDOWN. THE POST FLIGHT INSPECTION OF THE SPINNERS INDICATED THERE MIGHT BE SNOW INSIDE THE SPINNERS, BUT DUE TO THE LIMITED VIEW IN THE SPINNER OPENINGS, IT COULD NOT BE CONFIRMED. REMOVED THE SPINNERS & REMOVED SNOW FROM INSIDE BOTH SPINNERS. REINSTALLED THE SPINNERS. FLIGHT CREW RAN THE ENGS & VERIFIED THE VIBRATION WAS ELIMINATED. ACFT WAS RETURNED TO SERVICE WITH NO FURTHER DEFECTS NOTED.