What was found
DURING CLIMB OUT, A BURNING PLASTIC SMELL WAS ENCOUNTERED AND DID NOT GO AWAY UNTIL AFTER ENGINES WERE SHUT DOWN. NO SMOKE OR HAZE PRESENT AT ANY TIME. RAN AIRCRAFT WITH APU AND ENGINE RUNNING COULD NOT DUPLICATE BURNING PLASTIC SMELL. APU OFF AND ENGINES AT HIGH POWER RAN SYSTEM FULL HOT AND COULD NO DEFECTS NOTED. TRIED SINGLE SOURCE LEFT AND RIGHT AT HIGH POWER NO DEFECTS OR BURNING SMELLS NOTICED AT THIS TIME. COMPLIED WITH TASK TC-68A-21-181006MR2 ENVIRONMENTAL CONTROL SYSTEM BLEED AND TRIM AIR DUCT BURN PROCEDURE USING LT AND RT ENGINE, THEN APU. NO DEFECTS NOTED.