Final answer:
The T/R Quad Fail caution is displayed on the aircraft's caution and warning panel or EICAS, alerting pilots to a failure in the Thrust Reverser Quad Redundant system.
Step-by-step explanation:
The T/R Quad Fail caution is typically displayed on the caution and warning panel or the Engine Indicating and Crew Alerting System (EICAS) of an aircraft. This caution indicates that there has been a failure in the Thrust Reverser Quad Redundant system, which is a critical system used for decelerating the aircraft during landing. The specific location of this caution display can vary depending on the aircraft model, but it is generally found in the cockpit where it is clearly visible to the pilots to ensure prompt attention and corrective action.