How long after main gear touchdown does N1 revert back to ground idle?

The correct choice, indicating that N1 reverts back to ground idle 4 seconds after main gear touchdown, is based on specific aircraft operational parameters. Understanding this timing is crucial for pilots managing engine performance during landing operations.

When the main gear touches down, the aircraft's systems are engineered to ensure that power management occurs smoothly. The 4-second delay allows for any necessary adjustments in engine performance as the aircraft transitions from flight to ground operations. This transition time ensures that the engines respond appropriately to the change in aerodynamic conditions while providing power needed for braking, steering, and any required thrust during roll-out.

This timing is a key aspect of the T-6A's operational procedures. Familiarity with such protocol is essential not only for ensuring safety during landings but also for optimizing the aircraft's system management in various phases of flight.