Final answer:
TGT, or Turbine Gas Temperature, limiting engages to prevent engine damage by controlling the temperature in jet engines. It's managed by engine control systems like FADEC, with limits varying by operating conditions and specific engine models.
Step-by-step explanation:
The term TGT refers to Turbine Gas Temperature, which is a critical parameter in jet engines. The TGT limiting engagement, often with an M model engine, pertains to the maximum allowable turbine gas temperature threshold at which the engine's control system will begin to take action, such as reducing fuel flow to avoid damaging the engine. In most M model turbine engines, this limit varies depending on operational conditions but is typically programmed into the Full Authority Digital Engine (or Electronics) Control (FADEC) system to engage at predetermined temperature values, often measured in degrees Celsius or Fahrenheit. For example, during takeoff, TGT limits can be higher to allow for maximum power, but during cruise, the limits are set lower to maintain engine performance over time. In any case, the actual number can vary depending on the specific engine design, operational procedures, and the ambient environmental conditions.