Turn coordinator how does it work

The inclinometer does not indicate the amount of bank, nor does it indicate slip; it only indicates the relationship between the angle of bank and the rate of yaw. The turn indicator is a small gyro spun either by air or by an electric motor. The gyro is mounted in a single gimbal with its spin axis parallel to the lateral axis of the aircraft and the axis of the gimbal parallel with the longitudinal axis.

It is restrained in this rotation plane by a calibration spring; it rolls over just enough to cause the pointer to deflect until it aligns with one of the doghouse-shaped marks on the dial, when the aircraft is making a standard rate turn.

The major limitation of the older turn-and-slip indicator is that it senses rotation only about the vertical axis of the aircraft. It tells nothing of the rotation around the longitudinal axis, which in normal flight occurs before the aircraft begins to turn. Therefore during a turn, the indicator first shows the rate of banking and once stabilized, the turn rate. Some turn coordinator gyros are dual-powered and can be driven by either air or electricity.

Turn coordinators are installed on an aircraft's dashboard and are considered one of the pilot's primary instruments during flight. The miniature airplane component of the turn coordinator relays rate-of-turn information to the pilot and is a crucial component while flying under instrument flight rules IFR.

This allows air traffic controllers to estimate how long an aircraft will need before completing the assigned turn. A turn coordinator's second component, sometimes referred to as the slip and skid indicator, tells a pilot if his aircraft is in coordinated flight.

If the airplane is flying straight, the ball will be centered; otherwise, the ball will move to either side of the center. For example, if the aircraft is executing a left bank, yet the ball moves to the right, the aircraft is considered in a slip condition. If the ball moves in the direction of the bank, the plane is considered to be in a skid condition. The difference is that they are combined with other instruments and rather than relying on a spinning gyroscope, the AHRS attitude and heading reference system generates the outputs that get translated into the instrument readings.

The turn indicator is typically along the top of the HSI and is really a heading trend indicator along with up to two indices, one for half-standard rate and one for standard rate heading changes.

The slip and skid indicator is located just under the roll pointer. It is a small horizontal line that moves to either side indicating a slip or skid just as a ball would within an inclinometer. The other indication on the face of both the Turn and Slip Indicator and the Turn Coordinator is the inclinometer. This liquid filled tube has a slight curve to it and contains a ball. The ball will indicate how coordinated — or not — you are without regard to the bank angle.

If the aircraft is slipping, the ball will fall towards the inside of the turn meaning more rudder is required in the direction of the turn. If the aircraft is skidding, then less rudder is needed in the direction of the turn input is the way to go. For more reading on this topic, see our article on slipping vs. It is during IFR flight, though, that the real value of this important difference between the two instruments comes into play especially during partial-panel flight by reference to the instruments.

A quick glance at the Turn Coordinator will tell the pilot if the aircraft is moving about the longitudinal axis, i. This is why, during partial panel operations, the Turn Coordinator becomes the primary bank instrument. The other reason why the Turn Coordinator is a primary bank instrument when partial panel is because of its power source.

Unlike most traditional attitude indicators, the Turn Coordinator in most modern aircraft is electrically powered. This provides redundancy in case of a vacuum failure.

The Turn and Slip Indicator and the Turn Coordinator are checked in similar ways during the preflight inspection and before takeoff. Upon first entering the cockpit during preflight, the inclinometer should be observed. It is important to ensure that the glass tube is completely filled with liquid and that there are no bubbles visible.

Also, take a look at where the ball is sitting within the glass tube. If it is resting outside the lines on the glass tube but the aircraft appears to be sitting level along the longitudinal axis with neither wingtip above the other, this might be worth exploring a bit more.

Gently shake the aircraft by the wingtip and see if the ball moves to a more appropriate resting place. After startup and as you are taxiing out to the active runway, take a look at the instrument while executing a turn. The turn needle or aircraft silhouette should indicate a turn in the direction you are turning and the ball should indicate a skidding turn by moving to the outside of the turn.