PLT OF SMT TWIN ENG ATX ACFT EXPERIENCED AN UNSAFE LNDG GEAR POS INDICATION AND ACFT VIBRATION AFTER LIFTOFF. RETURN LAND.

Narrative

EVEN THOUGH I RETRACTED MY 'EMER' STATUS IN THIS SIT; THE FAA IS STILL REQUIRING ME TO SEND THEM A LETTER EXPLAINING WHAT HAPPENED. I HAVE ENCLOSED A COPY OF THAT LETTER. THE WHOLE PROB COULD HAVE BEEN AVOIDED BY NOT TAXIING THROUGH SLUSH; LIKE I DID ON THAT MORNING PRIOR TO DEP. THE RAMP AREAS WERE STILL WARM ENOUGH TO CREATE SLUSH; YET THE AMBIENT TEMP WAS WELL BELOW FREEZING. I DEPARTED DEN AT APPROX XX55 AM; RWY 36. AFTER I CLRED THE END OF THE RWY; I RETRACTED THE LNDG GEAR AND NOTICED THE GEAR UNLOCKED LIGHT REMAINED ON. KNOWING THE RAMP AREAS WERE SLUSHY THAT MORNING; I CYCLED THE GEAR 2 MORE TIMES TO SEE IF THAT WOULD SHED ANY SUSPECTED ICE BUILD-UP ON THE GEAR. EACH ATTEMPT FAILED TO TURN OFF THE GEAR UNLOCKED LIGHT; SO I PULLED THE LNDG GEAR CIRCUIT BREAKER. I THEN RE-ENGAGED THE CIRCUIT BREAKER AND THE GEAR UNLOCKED LIGHT WENT OUT. AT THAT TIME; I ASSUMED THAT THE SLUSH PROB HAD BEEN CORRECTED. AFTER ABOUT 10 MINS IN FLT; THE ACFT BEGAN TO VIBRATE ABOUT 20-30 MI W OF DEN VOR. AGAIN; I ASSUMED IT HAD SOMETHING TO DO WITH SLUSH ON THE BOTTOM OF THE ACFT. HOWEVER; THERE WAS NO INDICATION THAT THE GEAR HAD BECOME UNLOCKED. WHEN THE ACFT CONTINUED TO VIBRATE AFTER LEVELING OFF; AND NOT KNOWING THE EXTENT OF SLUSH ON THE AIRPLANE; I DECIDED TO DECLARE AN EMER AND RETURN TO STAPLETON. BY THE TIME DEN APCH STARTED VECTORING ME FOR THE ILS 36 APCH; ABOUT 20 MINS INTO THE FLT; THE ACFT BEGAN TO FLY SMOOTHLY WITH NO VIBRATION. AT THAT TIME; I DECIDED THE ACFT WAS FUNCTIONING NORMALLY AND REQUESTED THAT DEN APCH RETRACT MY EMER STATUS; WHICH THEY AGREED TO DO. IN ADDITION; I TOLD THEM THAT THIS WOULD BE A PRECAUTIONARY LNDG; NOT AN EMER LNDG. AFTER LNDG; I INSPECTED THE ACFT AND FOUND ICE BUILD-UP ON THE LNDG GEAR DOORS; STRUTS; AND WHEEL BRACKETS. I CLRED THE ENTIRE AIRFRAME OF ICE. SATISFIED THAT MY PROB WAS RESOLVED; I CONTINUED WITH THE FLT TO RIL; WHICH WAS UNEVENTFUL.