What happened
On May 26, 2023, a Cirrus SR22, registered as N522AR, was conducting an instrument flight from Pompano Beach Airpark, Florida, to Exuma International Airport in the Bahamas. While en route, the pilot in command noticed the engine was running roughly. In response to this mechanical irregularity, the pilot elected to divert to the nearest available airfield, Norman’s Cay Airport.
Although the pilot successfully completed the landing at Norman’s Cay, smoke was immediately visible emerging from the engine compartment. Shortly after the aircraft came to a stop, the smoke transitioned into an active fire. The crew evacuated the aircraft, and the flames were eventually suppressed using a mobile fire extinguisher. There were no injuries reported among the three occupants, though the aircraft sustained fire damage to the engine and the forward section of the fuselage.
The investigation
The investigation focused on the mechanical failure that triggered the engine instability and subsequent fire. Authorities reviewed the maintenance records of the aircraft, confirming that the plane had been maintained according to manufacturer and regulatory standards and held a valid certificate of airworthiness. The pilot was also found to be appropriately licensed and current for the flight.
Technical examination of the engine revealed that the cylinder head of the number three cylinder assembly had separated from its steel barrel. This separation occurred at the threaded interface where the aluminum head and steel barrel are permanently joined during manufacturing. While the exact reason for this structural separation remains undetermined, the physical consequences were clear.
Findings
- The separation of the #3 cylinder head from the cylinder assembly was the primary cause of the incident.
- This failure caused the fuel injection line to be torn away from the cylinder assembly.
- Raw fuel was pumped directly onto the hot cylinder assembly, where it was ignited by exposed, active spark plugs.
- The continuous operation of the engine-driven fuel pump during the landing and taxi phases provided a constant fuel source, sustaining the fire.
- Weather conditions at the time of the occurrence were not a contributing factor.