As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
TEST FLIGHT DISCREPANCY . . BURNING SMELL ON DESCENT PASSING 14K. DISSIPATED ON LDG. ONLY IN COCKPIT. PERFORMED OPS CK OF BOTH PACKS ON GROUND WITH APU REF AMM 21-00-00. COULD NOT DUPLICATE SMELL. OPS CK GOOD. NOTE: REF FIM 21-00 TASK 808. RAN ALL FANS, AND GALLEY EQUIPMENT, FLT DECK HEATERS AND OPERATED PACKS USING ENG AIR. NO ABNORMAL ODORS NOTED