Cirrus Design Corp SR22T N825JC incident near Tulsa, Oklahoma

Probable cause

The mechanic’s improper installation of the alternator wiring connections, which resulted in electrical arcing and thermal damage to the airplane.

NTSB analysis

An airframe and powerplant mechanic removed and replaced the airplane’s engine, which included rewiring the two alternators, and performed an engine run-up without incident. A pilot then performed a short ferry flight, also without incident. After parking the airplane at the destination airport and shutting down the engine, the pilot saw smoke coming from the engine compartment. The pilot exited the airplane, looked into the louvered vents under the engine compartment, and saw electrical arcing and smoke, but did not see any fire. The airplane battery and associated wiring sustained thermal damage. The airplane’s composite firewall sustained substantial damage due to thermal damage.

The mechanic who performed the engine replacement took a photograph of the alternator wire connections before removing the original engine, which he used as a reference when rewiring the alternator following the engine replacement. The photograph showed the correct wire connections, but those connections were different than those at the time of the accident. Postincident examination of the airplane revealed that the alternator wire connections were not done in accordance with the airplane manufacturer’s maintenance manual, which resulted in electrical arcing and substantial thermal damage to the airplane.

Text from the NTSB. Open the NTSB docket for CEN24LA308 for the full record.