DEPARTING ERI IN IMC PLT OF SMA DISCOVERED HIS MAGNETIC COMPASS WAS MALFUNCTIONING AND HIS DIRECTIONAL GYRO WAS PRECESSING RAPIDLY. DEP CTLR GAVE HDGS UNTIL COMPASS PROBLEM WAS RESOLVED.

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THE PROBLEM WITH THE ACFT DIRECTIONAL GYRO WAS KNOWN. THE PROBLEM WITH THE MAG COMPASS WAS NOT. YOU DO NOT EXPECT A PROBLEM WITH A COMPASS; THAT INDICATES KNOWN HDGS. COMPASS WILL 'STICK' ON A HDG; ADD THAT TO A DG THAT NEEDS RESET EVERY 5 MINS. UPON CLBOUT FROM ERI; DEP CTL CLRNC AS FOLLOWS WHEN ABOVE 2100 FT MY HDG 210 DEG DIRECT YNG WHEN ABLE. DUE TO THE LOW CEILING AND MY KNOWN DG I WANTED TO BE ON COURSE PRIOR TO PENETRATING THE CLOUD DECK AND GOING IMC. (THIS WAS ALSO THE FIRST INST WX IN A LONG WHILE. THE PREVIOUS DAY I PRACTICED 2 APCHS AND 1 HR HOOD TIME IN THIS ACFT KNOWING I WOULD BE IFR ACTUAL ON FRI). MY ACTUAL HDG AFTER CLBING ABOVE 2100 WAS 240 DEG ON MY DG HDG WAS 210 DEG. ON THE COMPASS 248 DEG. THE COMPASS WAS STUCK BTWN 240 AND 250. I HAD BOTH ERI AND YNG VOR UP AND IDENTED. THINKING I WAS TRACKING DIRECT YNG AS CLRED. AFTER 2 MINS APCH TOLD ME TO FLY HDG 210 DEG WHICH I BELIEVED I WAS. THEY SAID I WAS PROCEEDING DIRECT ERI. IN SUCH A SHORT PERIOD OF TIME MY ACTUAL HDG HAD NOT AFFECTED THE CDI FOR YNG. IN TIME IT WOULD HAVE. I WAS TRACKING BACK TO ERI HDG 240 DEG. ERI WAS USING RWY 6 POTENTIAL TFC CONFLICT HEAD ON. I TURNED 20 DEG L (30 DEG I SHOULD HAVE) SORTED OUT THE MAGNETIC COMPASS (GOT IT UNSTUCK BY TAPPING WITH FINGER) RESET THE DG (EVERY 4- 5 MINS) WHILE HAND FLYING ACFT. (NO AUTOPLT). IN IMC CONDITIONS TURNED ANOTHER 10 DEG L TO 210 DEG VERIFIED COMPASS UNSTUCK. PROCEEDED REST OF FLT NORMALLY.