Block 2 Exam Flashcards
What is variation?
- The difference between “true” and magnetic North
- Cannot be minimized
- Remains the same regardless of a/c heading
What is deviation?
- Magnetic fields from a/c electronics/wiring that cause the compasses reading to be off
- Can be minimized by aligning plane on a compass rose and adjusting the compasses compensating magnets
- Differs with a/c heading
What does the compass correction/deviation card tell us?
- The errors in compass reading that could not be fixed when a/c was adjusted on a compass rose
- Tells us the corrections that must be made to fly a certain Magnetic Heading
What is Northerly turning error?
- When the magnetic compass initially “jumps ahead” of the a/c and the turn, giving a false heading
- UNOS (undershoot north, overshoot south)
What is Southerly turning error?
- When the magnetic compass initially “lags” behind the a/c and turn, giving a false heading
- UNOS (undershoot north, overshoot south)
On what headings do Acceleration/Deceleration errors occur?
When flying on East and West headings! (A.N.D.S.)
If you began accelerating on an E/W heading, what error would the magnetic compass show?
The compass would indicate a turn to the North
If you began decelerating on an E/W heading, what error would the magnetic compass show?
The compass would indicate a turn to the South
What is oscillation error?
The result of all the other errors, and the swinging back and forth of the magnetic compass as it tries to line up
What are some characteristics of a Wet Vacuum Pump?
- Steel vanes require lubrication (engine oil)
- More common for low flying a/c
What are some characteristics of a Dry Vacuum Pump?
- Carbon vanes that are self-lubricating
- More common for high flying a/c
Characteristics of the Attitude Indicator?
- Relies on rigidity
- Vertical Spin Axis (allowing it to sense rotation about the a/cs lateral axis)
- Double gimbal mount, allowing the gyro to remain fixed in space as the a/c pitches and rolls around it
- Horizon disc, allowing gyro to remain on the same PLANE as the a/c
- Has an Erection Mechanism used to correct the effects of precession induced by friction
Characteristics of the Heading Indicator?
- Relies on rigidity
- Horizontal Spin Axis (allowing it to sense rotation about the a/cs vertical axis)
- Double gimbal mount
- Not a North seeking instrument so it must be manually set
- Air driven
Characteristics of the Turn-Slip Indicator?
- Relies on Precession (a/c yawing creates force on horizontal plane causing gyro/gimbal to spin)
- Shows relationship of inertia and gravity (Ball to the outside of the turn = increased inertia, ball to the inside of the turn = increased gravity)
- Gyro axis is parallel to a/c lateral axis
- Gimbal axis is parallel to a/c longitudinal axis (single gimbal mount)
Characteristics of the Turn Coordinator?
- Relies on Precession
- Shows relationship between bank angle and rate of yaw (Ball to the outside of the turn = SKIDDING, ball to the inside of the turn = SLIPPING)
- Gimbal frame is angled 30 degrees up from longitudinal axis of a/c
- Senses yaw and roll
What is an AHRS? How is it powered?
- Attitude and Heading Reference System
- ALL ELECTRICAL
- 3 rate sensors, 3 accelerometers (Determines which way is level and which way is north by using inertial sensors, rate gyros, and magnetometers)
- 2 axis tilt sensors
What is an ADC? What does it do?
- Air Data Computer
- Receives and processes pitot pressure, static pressure, and temperature
- Outputs altitude, indicated AS, true AS, and air temp.
What is an HSI? What does it include?
- Horizontal Situation Indicator
1. Direction Indicator (magnetic compass)
2. Course Deviation Bar (uses VOR/Localizer)
3. Course Indication Arrow
4. Glideslope Deviation Pointer
What does an Attitude Direction Indicator use to show attitude?
Combines gyro horizon with other instruments (such as HSI)
What would happen if the front of the pitot tube became blocked?
The ASI would drop to 0
In a traditional 6-Pack, what instruments have gyroscopes?
Attitude Indicator, Heading indicator, Turn-Slip Indicator, Turn Coordinator
What would happen to the Altimeter if the static port became blocked?
Altimeter be frozen at the altitude it was at when it became blocked.
How would the VSI be affected if the static port became blocked?
The VSI would indicate 0 (level flight)
What would happen if the front and back of the pitot tube became blocked?
- The pressure inside would become trapped, therefore the ASI would remain frozen at whatever airspeed in level flight
- ASI would increase if you entered a climb
- ASI woud decrease if you entered a descent
(acting like an altimeter)
What would happen to the ASI if the static port became blocked?
The ASI would give inaccurate readings
What powers the gyros?
Vacuum-driven: Uses suction/air pressure in vanes to maintain upright spinning parallel to ground
Electrically-driven: Uses electricity (only the Turn Coordinator in a standard 6-Pack)
What instrument(s) would you lose on an EFIS (electronic flight instrument system) if the Magnetometer failed?
Loss of Heading indicator.
What instrument(s) would you lose on an EFIS if the AHRS failed?
Screen background would go black…loss of horizon line and heading indicator.
What instrument(s) would you lose on an EFIS if the ADC failed?
Loss of Altitude, ASI and VSI
Will the EFIS display anything if there is a pitot/static blockage?
No, the EFIS does not monitor the pitot/static probes/ports so it will not recognize a blockage
What does the STBY Battery in our C172s power?
The Essential Bus:
- ADC/AHRS
- PFD
- Nav 1 (engine/airframe, Ess. Bus voltometer)
- Com 1
- STBY indicator lights
How long will the SBTY Battery last?
At least 30 minutes
When will the STBY Battery start powering things?
When M BUS Volts drops below 20
What is Equivalent Airspeed?
CAS corrected for compression effects (due to high speeds causing packing of air in pitot tube, usually above 10,000’)
What is Indicated Altitude?
Accounts for pressure, but not temperature.??
What instruments rely on Precession?
Turn-Slip Indicator, Turn Coordinator
What instruments rely on Rigidity in space?
Attitude Indicator, Heading Indicator
What is Absolute Altitude?
Height above the ground (AGL)
What is Pressure Altitdue?
Height above the standard datum (29.92” Hg)
What does the pitot probe measure?
RAM/Dynamic pressure
What happens to IAS as altitude increases?
- IAS decreases with altitude due to decreased pressure in the atmosphere (remember your cute example that sucked)
What is TAS?
True Airspeed, corrected for non-standard temperature and pressure.
How does the Altimeter work?
- Standard temp. and pressure is sealed inside wafers of altimeter
- Wafers EXPAND when climbing because air moves out
- Wafers COMPRESS when descending because air move in
What would happen if you flew from an area of lower pressure to an area of higher pressure without changing you altimeter?
You would be flying HIGHER than is indicated
What would most likely happen if you flew from an area with a hot temperature to an area with a colder temperature?
You would be flying LOWER than you were before
In a standard 6-Pack, what instruments operate on electricity?
Just the Turn Coordinator
What is rigidity in space?
When spinning at high speeds, gyros will resist tilting/turning in any direction other than around its spin axis
What is precession?
- The “rolling over” proportionate to the rate of the a/c’s rotation
- Any force is “felt” 90 degrees ahead of where it was originally applied
