Instrument Systems Flashcards

What type of gyroscope is used in modern Inertial Reference Systems instead of mechanical gyros?

Answer: Ring Laser Gyro (RLG) or Fiber Optic Gyro (FOG)

Modern IRS units use Ring Laser Gyros (RLGs) or Fiber Optic Gyros (FOGs), which have no moving parts and measure rotation via the Sagnac effect.

What does EICAS stand for and what is its primary function?

Answer: Engine Indication and Crew Alerting System

EICAS (Engine Indication and Crew Alerting System) displays engine parameters and generates crew alert messages for abnormal aircraft system conditions.

What is the function of a Flux Valve (flux detector) in an aircraft compass system?

Answer: Sense the direction of the Earth's magnetic field to provide a slaved magnetic heading

A flux valve (also called a flux gate) detects the horizontal component of the Earth's magnetic field to provide an accurate magnetic heading signal to the heading indicator or AHRS.

What does AHRS stand for and what sensors does it use?

Answer: Attitude and Heading Reference System — gyros, accelerometers, and magnetometers

AHRS (Attitude and Heading Reference System) uses solid-state gyroscopes, accelerometers, and magnetometers to compute aircraft attitude and magnetic heading.

What causes a static port blockage to affect aircraft instruments?

Answer: Freezes airspeed, altimeter, and VSI at the values present when blockage occurred

A blocked static port traps static pressure at the level when blocked, causing the altimeter, airspeed indicator, and VSI to freeze or show erroneous values.

Which component converts a synchro signal to a DC voltage for use in digital avionics?

Answer: Synchro-to-digital converter (SDC)

A Synchro-to-Digital Converter (SDC) translates the three-wire AC synchro signal from angular position sensors into a digital word for avionics computers.