As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LT ENGINE INTAKE HEAT MAT BEGAN TO SHOOT SPARKS, BURN INFLIGHT. AIRCRAFT RETURNED TO DTW. MAINTENANCE REPLACED LOWER DUCT ON LT ENGINE. RAN A/C HALF HR, OPS CHECK GOOD IAW SAAB MM 30-00-0. (P/N NH24668-169) (S/N OFF L283723) (S/N ON L198033).