In lockout, how is engine power limited?

In lockout, how is engine power limited?

• A. The main fuel manifold sets the limit
• B. The fuel pressure sensor sets the limit
• C. The LDS controls the maximum power
• D. Adjustment of the engine power control levers set the maximum power available to the HMU

Answer: (D)

In lockout, the maximum engine power is governed by the engine power control levers. Those levers provide the input signal to the Hydromechanical Unit (HMU), which is the fuel metering system that actually limits how much fuel the engine can receive. When the levers are set in lockout, they are restricted to a fixed, lower setting, so the HMU can only meter up to that amount of fuel. The engine cannot deliver more power than this limit, even if other parameters would suggest more fuel could be supplied. The main fuel manifold and fuel pressure sensor are part of the fuel delivery and monitoring system, but they do not establish the power limit by themselves. The LDS isn’t the mechanism for setting the lockout limit either. The essential control is the engine power control lever setting, which defines the maximum fuel the HMU can meter and thus the maximum power the engine can produce.

In lockout, the maximum engine power is governed by the engine power control levers. Those levers provide the input signal to the Hydromechanical Unit (HMU), which is the fuel metering system that actually limits how much fuel the engine can receive. When the levers are set in lockout, they are restricted to a fixed, lower setting, so the HMU can only meter up to that amount of fuel. The engine cannot deliver more power than this limit, even if other parameters would suggest more fuel could be supplied.

The main fuel manifold and fuel pressure sensor are part of the fuel delivery and monitoring system, but they do not establish the power limit by themselves. The LDS isn’t the mechanism for setting the lockout limit either. The essential control is the engine power control lever setting, which defines the maximum fuel the HMU can meter and thus the maximum power the engine can produce.