What is the T2 probe and where is it mounted?

• A. It is the fan inlet temperature sensing probe, one is located on each engine cowling.
• B. It measures cabin temperature.
• C. It monitors oil temperature in the gear box.
• D. It calibrates fuel flow for takeoff.

Answer: (A)

The T2 probe is the fan inlet temperature sensing probe. It measures the temperature of the air as it enters the engine, and that data is used by the engine control system to manage performance, starting, and safety functions (such as anti-ice and fuel metering adjustments).

On the CRJ-550, there is one T2 probe mounted on each engine cowling, positioned in the engine inlet area. This per-engine placement ensures the control system has accurate readings for each engine independently.

Other options don’t fit because T2 is not a cabin temperature sensor, not an oil temperature sensor in the gear box, and not a device used to calibrate fuel flow for takeoff.