As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
BURNING SMELL IN COCKPIT DURING CLIMB. TURNED OFF OVERHEAD A/C UNIT AND PULLED LOWER ROTATING BEACON BREAKER. SMELL DISAPPEARED SOME. NOTICE FAINT SMELL ON DESCENT. OPERATED COCKPIT A/C AFTER ROTATING BEACON REMOVED AND REPLACED. DURING ENGINE GROUND RUN, NO DEFECTS NOTED. COULD NOT DUPLICATE SMELL.