What happened
The incident occurred while the aircraft was taxiing on the ground. During this phase of operation, the crew observed that the number one engine fire warning light had illuminated. In response to this indication, both the pilot and the co-pilot immediately initiated an engine shutdown procedure. They proceeded to complete the appropriate emergency checklists and actions required for such a situation.
The investigation
Following the event, a physical examination of the aircraft was conducted to determine the root cause of the warning. The inspection revealed that the manifold associated with the number one engine was obstructed. Specifically, the blockage was caused by coking deposits within the component.
Findings
The obstruction led to a fuel spill, which subsequently ignited and caused a fire within the nacelle area. This mechanical failure explains the activation of the fire warning system during the taxi phase.