Incident Overview
On September 22, 2018, at approximately 20:15 local time, a single-engine business jet identified as a Cirrus SF50 Vision Jet with registration N474CG experienced a serious incident at Zurich Airport (LSZH). The aircraft was operated by I-Fly AG and owned by Southern Aircraft Consultancy Inc Trustee. The flight was a training mission conducted under Instrument Flight Rules (IFR), originating from Mainz-Finthen (EDFZ) in Germany.
Operational Context
The Pilot-in-Command (PIC), a Swiss national holding an FAA ATPL(A), flew the aircraft with four occupants on board. One passenger, a German national holding an EASA CPL(A) but lacking type rating for the SF50, sat in the left pilot seat as a student. The PIC occupied the right front seat, while three other individuals were seated in the rear. This was the student's second flight in this specific aircraft model.
Sequence of Events
The flight proceeded without incident until landing on Runway 28 at Zurich Airport at 20:09. During taxiing to General Aviation stand GA 1, the crew noticed a faint unusual odor. After parking and shutting down the engine two minutes later, the smell intensified, described by the student as an electrical burning scent.
Upon exiting the aircraft, the student observed white smoke emerging from the nose gear well and the edges of an access panel on the right side of the nose. The smoke was cool but the panel surface was hot to the touch. Inside the cockpit, the PIC noted that Battery 1 was still supplying 56 Amperes despite all consumers being off, with no corresponding alerts displayed on the Crew Alerting System (CAS).
Investigation Findings
The PIC disconnected Battery 1 approximately three minutes after engine shutdown, which stopped the smoke. Subsequent inspection by avionics technicians revealed significant fire damage and soot deposits in the area of the air conditioning system compressor. Specifically, severe burn marks were found at the electrical connections of the compressor, including a white hot spot above the positive terminal screw and a metallic melt bead nearby. No circuit breakers had tripped, and no warnings were generated by the aircraft's systems.
Technical analysis indicated that the compressor is powered via the Aft Master Control Unit (MCU) and protected by a 150A fuse. The Recoverable Data Module recorded a discharge current rising to 62 Amperes from Battery 1 to the AFT MCU main bus immediately after engine shutdown, which persisted until the battery was manually disconnected. The absence of warnings suggests a failure in the monitoring logic or protection circuitry for this specific subsystem.