What was found
FLT 1004, JFK-BOS, BURNING SMELL SIMILAR TO BURNING CURLING IRON, COMING FROM OVERHEAD COCKPIT VENT, DID NOT SEE SMOKE. SMELLED DURING CLIMBOUT, ON APPROACH NO EICAS MSG WITH SMELL. FOUND DAMAGED CABIN SUPPLY DUCT. REMOVED AND REPLACED DUCT PER AMM 21-24-03, RAN PACKS, OPS CHECK.