Instrument Systems

Question 1

Gyroscopes

Answer 1

Rotating Wheel.

Mounted so free to move.

Question 2

Electrical gyroscopic system

Answer 2

Helps with redundancy
•Typically powers Turn Coordinator
•Spools up the gyro through electrical current

Question 3

Venturi driven gyroscopic system

Answer 3

• Older Aircraft
• Located on the outside of airframe
• Uses Bernoulli’s Principle

Question 4

Pump driven pressure gyroscopic system

Answer 4

• Draws air through filter on pump side
• Pressure regulator opens/closes to regulate system pressure
• Pushes air through gyros
• Outlet is in the cockpit

Question 5

Pump driven vacuum system (gyroscopic system)

Answer 5

• Most common in newer aircraft
• Dry type vacuum pump

Draws air through the filter system
•Pulls air through Attitude and Heading indicator where it spins gyros
•Air continues to engine driven vacuum pump
•Vacuum Relief Valve- Prevents it from exceeding limits

Question 6

Vacuum gauge

Answer 6

• Allows for Pilot Check of system
• Low Reading: Instruments may not read correctly- Causes (pump problems, leaks, etc…)
• High Reading: Could damage instruments- Causes (obstructions), pressure relief valve

Question 7

Gyroscopic principles

Answer 7

• Rigidity in Space
• Remains in a fixed plane when spinning
• Gimbals instrument around gyro to allow it remain in place able to show changes in pitch and attitude
• Axis points in same direction

Question 8

Precession

Answer 8

• When outside force is applied to gyro it will be felt 90 degrees in rotation of spinning
• Includes friction

Question 9

Pitot-static system: total pressure

Answer 9

Pitot or ram pressure
•Supplied by pitot tube
•Location varies
•Needs to face directly into the relative wind
•Pressure caused by moving air (Dynamic)
•Only linked to airspeed indicator

Question 10

Pitot-static system: static air pressure

Answer 10

• Supplied by static port
• Location varies
• Needs to be in undisturbed air
• Pressure just outside of the airplane
• Linked to all instruments

Question 11

Alternate static source

Answer 11

When set to alternate position, the altimeter, VSI, and airspeed indicator on PFD and Aspen will use cabin air for static pressure.

Due to the venturi effect of the air flowing around the fuselage, the air pressure inside the cabin is lower than the exterior pressure
•When the alternate static source is used, the following instrument indications are observed:
•Altimeter: reads slightly higher than actual
•ASI: indicated greater than actual
•VSI: shows momentary climb then stabilizes if altitude is held constant