Which mechanism directly causes the starter motor to disengage in a gas turbine engine?

• A. Hydraulic detent
• B. Centrifugal force releasing the clutch
• C. Manual clutch release
• D. Electrical cut-off

Answer: (B)

The starter disengages automatically by centrifugal release. When starting, the starter is engaged to drive the engine through the accessory gearbox. As the engine accelerates and its speed surpasses the starter’s speed, centrifugal force on the clutch mechanism pushes the clutch to disengage (an overrunning action). This prevents the running engine from driving the starter, allowing the engine to continue accelerating on its own. Hydraulic detent, manual clutch release, and simply cutting power to the starter do not directly cause this mechanical disengagement, whereas centrifugal release is the mechanism that does.