How is hard alternate mode entered in the EEC?

How is hard alternate mode entered in the EEC?

• A. Retarding the thrust lever to idle
• B. Advancing the thrust lever to maximum
• C. Moving the start lever to OFF
• D. Activating soft alternate

Answer: (A)

Entering hard alternate mode is the EEC’s way of dropping back to a basic, non-FADEC control scheme so the engine can be kept safely running if the normal electronic control isn’t available. The trigger for this transition is moving the thrust lever to idle. When you pull the throttle back to idle, the EEC recognizes a request to switch to the simpler governing logic and disables the full FADEC control in favor of the hard alternate path. This allows the engine to be managed with reduced, but reliable, control to maintain a safe idle or stable condition. Advancing the thrust lever to maximum would command high power and isn’t a mode switch; moving the start lever to OFF would shut the engine down rather than engage alternate control; activating soft alternate is a different, less drastic fall-back that isn’t what triggers hard alternate in this case.

Entering hard alternate mode is the EEC’s way of dropping back to a basic, non-FADEC control scheme so the engine can be kept safely running if the normal electronic control isn’t available. The trigger for this transition is moving the thrust lever to idle. When you pull the throttle back to idle, the EEC recognizes a request to switch to the simpler governing logic and disables the full FADEC control in favor of the hard alternate path. This allows the engine to be managed with reduced, but reliable, control to maintain a safe idle or stable condition.

Advancing the thrust lever to maximum would command high power and isn’t a mode switch; moving the start lever to OFF would shut the engine down rather than engage alternate control; activating soft alternate is a different, less drastic fall-back that isn’t what triggers hard alternate in this case.