In a loss of hydraulic pressure to the nose wheel steering system, how many sweeps of steering authority does the emergency accumulator provide, and how is one sweep defined?

• A. Two sweeps; a sweep is movement of the tiller from 12 o'clock to the left or right and back to 12 o'clock
• B. One sweep; a sweep is movement from center to left and back
• C. Three sweeps; a sweep is movement from 12 o'clock to right and back
• D. Four sweeps; a sweep is rotation of the tiller through 360 degrees

Answer: (A)

When hydraulic pressure is lost in the nose wheel steering, the emergency accumulator provides a limited amount of steering authority so you can still maneuver on the ground. This energy allows two complete steering actions, or sweeps. A sweep is defined as moving the tiller from the centered position (12 o'clock) to one side (left or right) and then back to center. So you get one sweep to the left and back, and one sweep to the right and back, for a total of two sweeps. After the stored energy is used, further steering input from the tiller isn’t available. This is why two sweeps is the correct count, with the sweep defined by the center-to-one-side-and-back movement.