SMA PLT OBTAINS FLT ASSIST FROM APCH CTLR WHEN ACFT VIBRATION IS SENSED AFTER AN INFLT ENCOUNTER WITH ICING IS EXPERIENCED.

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WHILE IN IMC ON AN IFR FLT CLRNC FROM 0G7 TO N88 (SENECA FALLS; NY; TO DOYLESTOWN; PA; PHILADELPHIA AREA) AT ASSIGNED ALT OF 5000 FT I ENCOUNTERED UNFORECAST ICE. I RPTED THIS TO ATC AS REQUIRED BY FARS AT FIRST (FOR APPROX 5 MINS) ICE WAS ONLY A VERY SLIGHT TRACE OF RIME. AFTER 5 MINS RIME ICE BEGAN TO FORM BEYOND A TRACE AT WHICH POINT I AGAIN RPTED TO ATC. THEY ASKED MY INTENTIONS AND I REQUESTED A RPT OF THE TOPS. THEY ASKED A NEARBY AIRLINER FOR A RPT AND THEY RPTED ON TOP AT 7000 FT MSL. I THEN ASKED FOR AND RECEIVED A CLRNC TO 7000 FT (AGAIN TO COMPLY NOT ONLY WITH THE FARS CONCERNING CONTINUANCE OF A FLT IN ICE; ETC; BUT ALSO TO AVOID ANY POSSIBLE PROBLEMS WITH THE BUILDUP OF ICE AFFECTING THE SAFETY OF THE FLT; ETC). UPON CLBING THROUGH 5000 FT MSL I NOTICED A SLIGHT VIBRATION START; SEEMING TO COME FROM CARGO/TAIL SECTION OF ACFT. AT THIS POINT I WASN'T SURE IF VIBRATION WAS REAL OR THE PRODUCT OF MY IMAGINATION AT THE TIME DUE TO THE TURB IN SOLID IMC COUPLED WITH THE THREAT OF POSSIBLY HAVING TO DEAL WITH ICE. UPON REACHING CLRNC LIMIT OF 7000 FT MSL; I LEVELED OFF ONCE AGAIN IN CRUISE AND OVER THE NEXT 2-3 MINS AGAIN REASSESSED MY SITUATION. I WAS NOW IN AND OUT OF THE TOPS BUT MORE 'IN' THAN 'OUT'. ICE WAS NO LONGER FORMING ON THE ACFT BUT I HAD PICKED UP MORE ICE ON MY CLB TO 7000 FT MSL. THE ACFT NOW HAD A DEFINITE VIBRATION ORIGINATING FROM THE REAR AREA OF THE ACFT SO I CONTACTED APCH CTL ADVISING THEM I HAD PICKED UP ICE ON THE CLB; WAS STILL IMC AT 7000 FT AND HAD A VIBRATION THAT I FELT NEEDED TO BE CHKED OUT. I REQUESTED AND RECEIVED AN IMMEDIATE DSCNT AND VECTORS TO THE NEAREST ARPT WHICH WAS BGM. UPON DSNDING TO MY ASSIGNED ALT OF 3000 FT MSL I BROKE OUT AT APPROX 2200 FT AGL WITH THE ARPT AT 12 O'CLOCK AND 6 MI. LNDG WAS UNEVENTFUL. UPON CHKING OUT ORIGIN OF NOISE I FOUND THAT DUE TO THE TURB DURING THE CLB; A PREHEATER (SELF CONTAINED IN A METAL TOOL BOX TYPE UNIT) HAD SHIFTED REARWARD APPROX 1/2-1 INCH FROM WT OF MY SUITCASE IN FRONT OF IT (BOTH WERE STRAPPED DOWN SECURELY WITH TIE DOWNS MOUNTED TO FRAME OF ACFT) AND HAD BEGUN TO VIBRATE FROM CONTACT WITH REAR PLASTIC WALL OF CARGO HOLD. AFTER REARRANGING THE LOAD; I OBTAINED ANOTHER BRIEFING FROM FSS AND COMPLETED FLT VFR TO DEST N88 UNEVENTFULLY; AFTER KNOCKING OFF REMAINING ICE FROM AIRFRAME. I HAD ADVISED ATC DURING THE DSCNT THAT I SUSPECTED THE CAUSE OF THE VIBRATION WAS FROM SOME HEATER PIPES I HAD IN CARGO HOLD BUT WANTED TO LAND AND CHK IT OUT FOR SURE. CTLR RESPONDED 'ROGER' AND ASKED IF I WANTED HER TO ROLL THE EQUIP TO WHICH I DECLINED AS I DIDN'T FEEL THE SITUATION WARRANTED THIS MEASURE.