As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ABOUT 2 MIN AFTER SELECTING AIRFOIL ANTI-ICE A BURNING ODOR ENTERED THE CABIN AND WAS DETECTABLE IN THE COCKPIT. SMELL WENT AWAY WHEN AIRFOIL ANTI-ICE WAS TURNED OFF. ODOR WAS APPARENT ALSO WHEN TAIL DE-ICE WAS SELECTED. REMOVED AND REPLACED APU. OPS AND LEAK CHECK GOOD. (M)