Narrative:

While in IMC on an IFR flight clearance from 0g7 to N88 (seneca falls, ny, to doylestown, PA, philadelphia area) at assigned altitude of 5000 ft I encountered unforecast ice. I reported this to ATC as required by FARS at first (for approximately 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 reported to ATC. They asked my intentions and I requested a report of the tops. They asked a nearby airliner for a report and they reported on top at 7000 ft MSL. I then asked for and received a clearance to 7000 ft (again to comply not only with the FARS concerning continuance of a flight in ice, etc, but also to avoid any possible problems with the buildup of ice affecting the safety of the flight, etc). Upon climbing through 5000 ft MSL I noticed a slight vibration start, seeming to come from cargo/tail section of aircraft. At this point I wasn't sure if vibration was real or the product of my imagination at the time due to the turbulence in solid IMC coupled with the threat of possibly having to deal with ice. Upon reaching clearance 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 aircraft but I had picked up more ice on my climb to 7000 ft MSL. The aircraft now had a definite vibration originating from the rear area of the aircraft so I contacted approach control advising them I had picked up ice on the climb, was still IMC at 7000 ft and had a vibration that I felt needed to be checked out. I requested and received an immediate descent and vectors to the nearest airport which was bgm. Upon descending to my assigned altitude of 3000 ft MSL I broke out at approximately 2200 ft AGL with the airport at 12 O'clock and 6 mi. Landing was uneventful. Upon checking out origin of noise I found that due to the turbulence during the climb, a preheater (self contained in a metal tool box type unit) had shifted rearward approximately 1/2-1 inch from weight of my suitcase in front of it (both were strapped down securely with tie downs mounted to frame of aircraft) 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 flight VFR to destination N88 uneventfully, after knocking off remaining ice from airframe. I had advised ATC during the descent that I suspected the cause of the vibration was from some heater pipes I had in cargo hold but wanted to land and check it out for sure. Controller responded 'roger' and asked if I wanted her to roll the equipment to which I declined as I didn't feel the situation warranted this measure.

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Original NASA ASRS Text

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

Narrative: 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.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.