Which component is integral to the engine fire warning system alongside the core element and sensor tube?

The responder assembly is a critical component of the engine fire warning system because it is responsible for processing the signals received from the sensor tube and determining whether a fire condition exists in the engine. When the sensor tube detects excessive heat or a rapid rise in temperature, it relays this information to the responder assembly, which then activates the warning indicators in the cockpit. This provides vital information to the pilot, allowing for timely responses in the event of an emergency.

Components like a temperature gauge or a thermostat do play roles in monitoring engine performance and operational parameters, but they do not directly contribute to the fire warning system's capability to detect fires and alert the crew. A control panel provides the interface for the pilot but is not integral to the actual detection and warning process. Thus, the responder assembly is essential for ensuring that the fire warning system functions properly and informs the crew of any fire-related hazards.