When the aircraft yaws, or rotates about its vertical axis, it produces a force in the horizontal plane that, due to precession, causes the gyro and its gimbal to rotate about the gimbal's 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
A red flag shows the instrument is in a non-operational status
Inclinometer is located below the instrument used to determine quality of a turn (angle of bank and the rate of yaw)
The words printed 2-minutes means a standard rate turn held for 2-minutes would result in a 360° turn
This ball measures the relative strength of the force of gravity and the force of inertia caused by a turn
Gyroscopically driven using the principle of precession
A line indicates the standard rate turn
Mounted with about a 30 - 35° canted on the gyro
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
Slip: rate of turn is too slow for the angle of bank
Skid: rate of turn is too great for the angle of bank
Turn and Slip Indicator
The turn and slip indicator is an older design, and provides rate of turn and roll information [Figure 2]
Because the gyro is mounted along the aircraft's longitudinal axis, yaw and roll information are not provided
Turn & slip indicators therefore only show rate of turn.
Turn Coordinator Indications:
Turn coordinators precisely indicate the quality of turn, and generally the rate-of-turn.
Specific rate of turn indications relate to standard rate turns:
When the miniature aircraft (or the needle is straight up and down), the aircraft is straight and level
When the miniature aircraft (or needle) is aligned with one of the turn alignment marks, it is in a standard rate turn
A standard rate turn is defined as an aircraft turning at 3° per second
This standard turn rate is dependent upon True Airspeed and so the faster an aircraft is moving, the more angle of bank is required to achieve this set 3° rate
SRT Angle of Bank = [True Airspeed in Knots / 10] + 5
Turn Coordinator Preflight Actions:
Upon engine start and the activation of the gyroscopes (vacuum or electrical system), any flags should disappear.
As the aircraft begins to taxi, the aircraft should indicate a bank in the direction of taxi turns and the ball inside the inclinometer should deflect outward from the turn.
Inertial Reference Unit (IRU), Inertial Navigation System (INS), and Attitude Heading Reference System (AHRS)
IRUs are self-contained systems comprised of gyros and accelerometers that provide aircraft attitude (pitch, roll, and heading), position, and velocity information in response to signals resulting from inertial effects on system components.
Once aligned with a known position, IRUs continuously calculate position and velocity. IRU position accuracy decays with time.
This degradation is known as "drift."
INSs combine the components of an IRU with an internal navigation computer.
By programming a series of waypoints, these systems will navigate along a predetermined track.
AHRSs are electronic devices that provide attitude information to aircraft systems such as weather radar and autopilot, but do not directly compute position information.
Aircraft equipped with slaved compass systems may be susceptible to heading errors caused by exposure to magnetic field disturbances (flux fields) found in materials that are commonly located on the surface or buried under taxiways and ramps.
These materials generate a magnetic flux field that can be sensed by the aircraft's compass system flux detector or "gate", which can cause the aircraft's system to align with the material's magnetic field rather than the earth's natural magnetic field.
The system's erroneous heading may not self-correct.
Prior to take off pilots should be aware that a heading misalignment may have occurred during taxi.
Pilots are encouraged to follow the manufacturer's or other appropriate procedures to correct possible heading misalignment before take off is commenced.
Turn Coordinator Anamolies & Malfunctions:
Private Pilot (Airplane) Operation of Aircraft Systems Airman Certification Standards:
Objective: To determine whether the applicant exhibits satisfactory knowledge, risk management, and skills associated with safe operation of systems on the airplane provided for the flight test.
Private Pilot (Airplane) Operation of Aircraft Systems Skills:
The applicant exhibits the skills to:
PA.I.G.S1:
Operate at least three of the systems listed in K1a through K1l appropriately.
PA.I.G.S2:
Complete the appropriate checklist(s).
Private Pilot (Airplane) Systems and Equipment Malfunctions Airman Certification Standards:
Objective: To determine whether the applicant exhibits satisfactory knowledge, risk management, and skills associated with system and equipment malfunctions appropriate to the airplane provided for the practical test
Causes and remedies for smoke or fire onboard the aircraft.
PA.IX.C.K4:
Any other system specific to the airplane (e.g., supplemental oxygen, deicing).
PA.IX.C.K5:
Inadvertent door or window opening.
Private Pilot (Airplane) Systems and Equipment Malfunctions Risk Management:
The applicant is able to identify, assess, and mitigate risk associated with:
PA.IX.C.R1:
Checklist usage for a system or equipment malfunction.
PA.IX.C.R2:
Distractions, task prioritization, loss of situational awareness, or disorientation.
PA.IX.C.R3:
Undesired aircraft state.
PA.IX.C.R4:
Startle response.
Private Pilot (Airplane) Systems and Equipment Malfunctions Skills:
The applicant exhibits the skills to:
PA.IX.C.S1:
Describe appropriate action for simulated emergencies specified by the evaluator, from at least three of the elements or sub-elements listed in K1 through K5 above.
