Primary finding
Probable cause
The mechanic’s improper installation of the alternator wiring connections, which resulted in electrical arcing and thermal damage to the airplane.
Investigator assessment
Analysis narrative
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.
Source record
Factual narrative
On August 3, 2024, at 1300 central daylight time, a Cirrus SR22T, N825JC, was involved in an incident near Tulsa, Oklahoma. The airplane sustained substantial damage after the engine was shut down. The pilot was uninjured. The airplane was operated under Title 14 Code of Federal Regulations Part 91 as a ferry flight. Before the ferry flight, an airframe and powerplant mechanic with inspection authorization installed the engine onto the airplane by. The engine installation also included the installation of alternators 1 and 2. The mechanic was not affiliated with a certificated aircraft repair station or Cirrus Aircraft. The mechanic performed an engine run-up, but there was no test flight before the accident flight. The pilot flew the airplane from Tulsa Riverside Airport (RVS), Tulsa, Oklahoma, to Tulsa International Airport (TUS), Tulsa, Oklahoma, where the airplane’s parachute was to be repacked. After the approximate 10-minute flight, the pilot parked and shut down the airplane, and while the pilot was still seated in the airplane, line personnel saw smoke coming from the engine compartment. The pilot looked up and saw light white smoke coming from around the propeller spinner. As the pilot exited the airplane, the intensity of the smoke increased, and it changed to a darker color. The pilot looked into the louvered vents under the engine compartment and saw electrical arcing and smoke, but did not see any fire. The pilot called the fire department and sprayed halon through the louvered vents. Line personnel sprayed a dry multipurpose extinguisher into the airplane’s engine oil access door. Two fire department trucks then arrived and extinguished the fire. Postincident examination of the airplane revealed that the external wire connections to alternator 1 (Plane Power, model number ES10024, serial number H-X092248) were not in accordance with the Cirrus Airplane Maintenance Manual (AMM). Photograph 1 shows the airplane’s alternator 1 installation, and Photograph 2 shows an exemplar installation of alternator 1 in accordance with the Cirrus AMM. Photograph 1 – Alternator Installation at the Time of the Incident Photograph 2 – Alternator Installation in Accordance with the Cirrus Airplane Maintenance Manual Models SR22 and SR22T Photograph 3 is the photograph taken by the airframe and powerplant mechanic before the engine/alternator removal and the photograph that he stated he used as reference to rewire alternator 1. Photograph 3 - Photo Before Engine/Alternator Removal An airplane logbook entry by the mechanic, dated August 10, 2023, at a Hobbs time of 1,122.4 hours, stated that a rebuilt engine and both alternators were installed. An airplane logbook entry by the mechanic, dated July 22, 2024, at a Hobbs time of 1,138.1 hours, stated the engine was removed due to a loss of oil pressure, a rebuilt engine was installed, and both alternators were installed. The airplane battery and associated wiring sustained thermal damage. The airplane’s composite firewall sustained substantial thermal damage.