Remote Indicating Magnetic CompassNavigation — Instrumentation — DGCA CPL practice questions

All 6 questions — Remote Indicating Magnetic Compass

Navigation — Instrumentation · DGCA CPL. The correct option is marked on each.

1. Q1. A gyro-magnetic compass or magnetic heading reference unit is an assembly which always consists of:

   • A.2 and 5
   • B.1, 3 and 5✓
   • C.2, 3 and 5
   • D.1 and 4

   Why: The gyro-magnetic compass always requires: (1) a directional gyro (horizontal gyro) — provides short-term stability; (3) an earth's magnetic field detector (flux valve) — provides long-term magnetic reference; (5) a synchronizing control (rapid synchronization facility). Statement 2 (vertical axis gyro) is wrong — the gyro in the RIMC is a horizontal gyro (like a DGI), not a vertical axis gyro. Statement 4 (azimuth control) is not a standard separate component — the precession motor performs azimuth correction, but it is not called an "azimuth control" as a named element. See Section 3 . —…

2. Q2. A slaved directional gyro derives its directional signal from:

   • A.a direct reading magnetic compass
   • B.the flight director
   • C.the flux valve✓
   • D.the air data computer

   Why: The slaved directional gyro in the RIMC/gyro-magnetic compass derives its long-term directional reference from the flux valve (magnetic detector unit). The flux valve senses the earth's magnetic field and generates an error signal if the gyro drifts from alignment. See Section 4 . — The flux valve is the magnetic "brain" of the system. The DRMC is a separate backup and is not the input to the RIMC's slaving system.

3. Q3. The gyro-magnetic compass torque motor:

   • A.causes the directional gyro unit to precess✓
   • B.causes the heading indicator to precess
   • C.feeds the error detector system
   • D.is fed by the flux valve

   Why: The precession motor (torque motor) receives the amplified, phase-detected, DC error signal and uses it to turn (precess) the horizontal gyro. The gyro's rotation is then transmitted via the direct drive shaft to the heading indicator, changing the compass card reading. See Section 4 . — Signal flow: Flux valve → Error detector → Amplifier → Precession motor → Gyro → Drive shaft → Heading indicator. The motor acts on the gyro.

4. Q4. The heading information originating from the gyro-magnetic compass flux valve is sent to the:

   • A.error detector✓
   • B.erector system
   • C.heading indicator
   • D.amplifier

   Why: The flux valve senses the earth's magnetic field and recreates it (via the 3-leg stator) around the direct drive shaft in the compass unit. This recreated field is compared with the position of the gyro drive shaft rotor (error detector / rotor-stator comparison). The comparison generates the error signal. See Section 9 . — Flux valve → Error detector (rotor-stator) → Amplifier → Motor → Gyro → HI. Each step in order. The flux valve's first contact point is the error detector.

5. Q5. The input signal of the amplifier of the gyro-magnetic compass resetting device originates from the:

   • A.directional gyro erection device
   • B.error detector✓
   • C.flux valve
   • D.directional gyro unit

   Why: The precession amplifier's input is the AC error signal generated by the rotor-stator comparison (error detector). The amplifier then amplifies, phase-detects, and rectifies this signal before passing it to the precession motor. See Section 9 . — The amplifier is in the middle of the chain: Error detector → Amplifier → Motor. Its INPUT is always the error signal from the detector. Its OUTPUT drives the motor.

6. Q6. A flux valve senses the changes in orientation of the horizontal component of the earth's magnetic field:

   • A.2, 3 and 5✓
   • B.1, 3, 4 and 5
   • C.3 and 5
   • D.1, 4 and 5

   Why: Statement 2 — CORRECT: The primary coils of the flux valve are fed AC voltage, which creates anti-phase fields in the flux valve legs. See Section 8 . Statement 3 — CORRECT: The flux valve (flux gate) output can be used by a gyro-magnetic (flux gate) compass or as an input to a DGI slaving system. Statement 5 — CORRECT: The flux valve provides high accuracy magnetic field indication (less than 0.5% error). Statement 1 — INCORRECT: The flux valve is a 3-spoked device, not a pair of soft iron bars. The legs are made of a material that saturates magnetically at a defined level. Statement 4 — I…