FAA Instrument Rating Airplane (IRA)Flight Instruments and SystemsMedium
A technician is troubleshooting a turn coordinator that displays roll and yaw information differently than a standard turn-and-slip indicator. Which design feature explains why the turn coordinator senses both roll rate and yaw rate?
- AIt relies solely on the vacuum system, unlike the turn-and-slip indicator
- BIt uses a vertically mounted gyro that only detects pitch changes
- CIt measures magnetic heading changes directly instead of gyroscopic precession
- DIts gyro spin axis is canted upward at an angle to the longitudinal axis, allowing it to sense roll as well as yaw
Show answer & explanationAnswer & explanation
Correct answer: D. Its gyro spin axis is canted upward at an angle to the longitudinal axis, allowing it to sense roll as well as yaw
The turn coordinator's gyro is mounted with its spin axis canted upward, so precession causes the instrument to respond to both roll rate and yaw rate, unlike the turn-and-slip indicator's gyro, which is mounted with the spin axis parallel to the lateral axis and senses only yaw.
Why the other options are wrong
- A. Turn coordinators are typically electrically driven, not vacuum-driven.
- B. A vertical spin axis would sense pitch, which is not how a turn coordinator is built.
- C. The turn coordinator relies on gyroscopic precession, not direct magnetic sensing.
Turn Coordinator Gyro Design
The turn coordinator's gyro spin axis is canted upward relative to the longitudinal axis so the instrument responds to both roll rate and yaw rate, unlike the turn-and-slip indicator.
- Canted gimbal enables sensitivity to roll entry
- Electrically powered, providing backup if vacuum fails
- Turn-and-slip indicator only senses yaw (rate of turn)
Memory trick: Canted gimbal catches roll AND yaw.