Under which conditions does the external overspeed and overtemp assembly initiate an engine shutdown?

Under which conditions does the external overspeed and overtemp assembly initiate an engine shutdown?

• A. When the engine oil pressure drops.
• B. When Turbine Outlet Temperature (TOT) exceeds 1,500°F or speed exceeds 15,800 rpm.
• C. When ambient temperature exceeds 100°F.
• D. When generator voltage goes out of range.

Answer: (B)

External overspeed and overtemp protection keeps the engine from damage by watching two critical limits: turbine outlet temperature and engine speed. If the turbine outlet temperature rises above 1,500°F, or the rotational speed climbs beyond 15,800 rpm, the protection system trips and the engine is shut down to prevent thermal or mechanical failure. These thresholds are chosen to keep the turbine within its safe operating envelope, protecting blades, bearings, and overall integrity. Other fault conditions, like oil pressure loss, ambient temperature, or generator voltage out of range, are handled by different protection systems or are not immediate indicators of an overheat or overspeed situation, so they don’t trigger this particular shutdown mechanism.

External overspeed and overtemp protection keeps the engine from damage by watching two critical limits: turbine outlet temperature and engine speed. If the turbine outlet temperature rises above 1,500°F, or the rotational speed climbs beyond 15,800 rpm, the protection system trips and the engine is shut down to prevent thermal or mechanical failure. These thresholds are chosen to keep the turbine within its safe operating envelope, protecting blades, bearings, and overall integrity.

Other fault conditions, like oil pressure loss, ambient temperature, or generator voltage out of range, are handled by different protection systems or are not immediate indicators of an overheat or overspeed situation, so they don’t trigger this particular shutdown mechanism.