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Aircraft Flight Instruments

Aircraft Flight Instruments
Aircraft Flight Instruments

Objective: The student will be reviewing the flight instruments and going into more depth

Completion Standards: the student will be able to explain the different flight instruments in greater detail than they have before.

References: IFH Ch5, PHAK Ch8

Equipment: White Board and markers, iPad/ computer 

IP’s Actions:

  • Assess student

  • State the objective and completion standards

  • Writes down references

  • Provide attention getter

  • Present content

  • Assessment

  • Assign Homework

SP’s Actions:

  • Take notes

  • Ask Questions

Introduction: 

(Attention Getter) : (Link goes here)

Motivation: (Discuss purpose for lesson and relate to Attention getter)

Overview:

  1. Pitot-static System

  2. Vacuum System

  3. Attitude Indicator

  4. Heading indicator

  5. Turn and slip indicator

  6. Turn Coordinator

  7. Horizontal Situation Indicator (HSI)

  8. Radio Magnetic Indicator

  9. Magnetic Compass

  10. Electrical System

  11. Electronic Engine Instrument Display

  12. Primary Flight Display

Content:

Flight instrument systems

Minimum Equipment 

  • Similar to A-Tomato-Flames and Flaps {Addition}

GRABCARD

G-enerator/ Alternator

R-Adios/ Navigation

A-ttitude indicator

B-All/ puck

C-lock

A-ltimeter

R-ate of turn indicator

D-irectional Gyro / HSI


Pitot-static System

Overview


  1. The pitot tube is only connected to the airspeed indicator. 

  2. While the static port is connected to all three instruments.

Sensitive Altimeter

  • A sensitive altimeter is an aneroid barometer that measures the absolute pressure of the ambient air and displays it in terms of feet or meters above a selected pressure level


  • A line allows outside air through static line to enter the housing compressing or expanding the wafers


  • Altimeter errors

    • Designed to indicate standard changes

    • Mechanical altimeter errors

      • The altimeter should indicate the surveyed elevation of the airport. 

      • If the indication is off by more than 75 feet from the surveyed elevation

    • Inherent altimeter error

      • High pressure to low pressure

        • Aircraft will be lower

      • Low to high pressure

        • Aircraft will be higher

      • When the aircraft is flying in air that is warmer than standard, the air is less dense and the pressure levels are farther apart

      • If the air is colder than standard, it is denser and the pressure levels are closer together

Extreme cold (TERPS and ❄)

  • Cold temperature induced altimeter error may be significant when temperatures are well below standard.

    • For safety, minimum altitudes should be increased when flying at low terrain clearances


VSI (Vertical Speed indicator)

  • Also known as rate of climb indicator

  • indicates whether the aircraft is climbing, descending, or in level flight

    • differential pressure instrument

    • contains a diaphragm which is connected to the static line

    • the case/ housing is connected to the line as well but is restricted (calibrated leak)


Airspeed Indicator

  • measures the difference between pitot (impact/dynamic pressure) and static pressure.

    • Uses pitot tube and static line

    • Static line goes to case

    • Ram air/ dynamic air goes to diaphragm




Clogs and Malfunctions

Clogs happen most often in flying through ice accumulation. A clogged pitot tube will only affect the airspeed indicator. 

While a clogged static port will affect all of the pitot-static instruments

Airspeed Indicator

Pitot Tube – 

  1. This would mean no ram air pressure is being sent to the diaphragm. 

    1. the pressure would equalize and would make the ASI read 0

  2. If there is no ram air but the drain hole is clear 

    1. diaphragm will cease to expand and contract with increases and decreases in airspeed.

    2.  Essentially making the airspeed indicator act like an altimeter 

Static Port – 

  1. A clogged static port will affect the airspeed indicator by displaying slightly erroneous information.

  2. Let’s assume the static port gets clogged while flying at 5,000’ MSL. This would trap 5,000’ air in the static area of the airspeed indicator and cause the diaphragm to expand and contract incorrectly at higher and lower altitudes.

Altitude Indicator

Static port – 

  1. The altimeter will freeze at the altitude where the clog occurred. 

  2. This is because there will be no changing static pressure inside the instrument casing and therefore no expanding and contracting of the pre-sealed aneroid wafer.

VSI

Static Port – 

  1. A clogged static port will cause no change in static pressure in the Vertical Speed Indicator’s Diaphragm or in the pressure flowing out of the calibrated leak. 

  2. Therefore, the VSI will drop to a 0 indication and freeze there.


How to fix Clogs (2 ways)

Pitot Tube

  • Turn on heat

Alt Static source 

  • Airspeed Indicator = Slight increase in airspeed.

  • Altimeter = Slight increase in altitude.

  • Vertical Speed Indicator = Slight increase before returning to normal indications.


Vacuum System

  • The aircraft’s vacuum system is typically run via vacuum pump connected to the aircraft’s engine. 

  • The vacuum pump sucks air through the vacuum system to power the vacuum associated instrument gauges


System Components

The vacuum system typically consists of the following components:

  • Air Filter

  • Suction Gauge

  • Associated Instruments

  • Relief Valve

  • Engine Driven Pump










Principles of gyroscopes

  • Rigidity in space

    • Refers to the principle that a gyroscope remains in a fixed position in the plane in which it is spinning

    • Like bike wheels

  • Precession

    • The tilting or turning of a gyro in response to a deflective force

    • The reaction to this force does not occur at the point at which it was applied; rather, it occurs at a point that is 90° later in the direction of rotation

Errors

While gyroscopes are efficient at remaining “Rigid in Space,” they can “tumble” when excessive forces are applied.

  • Attitude Indicator = 60-70 degrees pitch and/or 100-110 degrees bank.

  • Heading Indicator = Excessive bank angle.

  • Turn Coordinator = Excessive bank angle.


Attitude Indicator

  • Attitude Indicator (operated through a vacuum)

    • Is mounted in a horizontal plane and depends upon rigidity in space for its operation.








Heading Indicator/horizontal Situation Indicator/Radio Magnetic Indicator

Heading indicator

  • Manually set (Magnetic Heading)

  • Vertically mounted Gyro

    • Rigid In Space



Turn and slip indicator

  • Single gimbal with its spin axis parallel to the lateral axis of the aircraft and the axis of the gimbal parallel with the longitudinal axis.

  • When the aircraft yaws, or rotates about its vertical axis, it produces a force in the horizontal plane that, due to precession, causes the gyro and its gimbal to rotate about the gimbal’s axis


Turn Coordinator

  • its gimbals frame is angled upward about 30° from the longitudinal axis of the aircraft

    • This allows it to sense both roll and yaw

  • Relies on precession 



Horizontal Situation Indicator (HSI)

  • Is a direction indicator that uses the output from a flux valve to drive the dial, which acts as the compass card

  • combines the magnetic compass with navigation signals and a glideslope


Radio Magnetic Indicator

  • Developed to compensate for older heading indicators

  • Depicts where you are located via and ADF or VOR

    • Homing

      • Points to 0 relative to bearing

    • Tracking

      • Needle moving left = wind from the left. 

      • Needle moving right = wind from the right


Magnetic Compass

Overview

Principles

A magnet is a piece of material, usually containing iron, which attracts and holds lines of magnetic flux.


NORTH AND SOUTH MAGNETIC POLES

  • UNLIKE POLES ATTRACT EACH OTHER AND LIKE POLES REPEL EACH OTHER.


EARTH’S MAGNETIC FIELD

  • Extends from the Earth’s inner core to where it meets the solar wind; 

    • a stream of energetic particles emanating from the Sun.

  • Unlike the field of a bar magnet, 

    • Earth’s magnetic field changes over time because it is generated by the motion of molten iron alloys in the Earth’s core.


LINES OF MAGNETIC FLUX

  • A measure of the quantity of magnetism, 

    • being the total number of magnetic lines of force passing through a specified area in a magnetic field.


TRUE - NORTH/SOUTH

  • The direction along the earth’s surface towards the geographic North Pole.


MAGNETIC - NORTH/SOUTH

  • The point on the surface of Earth’s Northern Hemisphere at which the planet’s magnetic field points vertically downwards. 

    • The North Magnetic Pole moves over time due to magnetic changes in the Earth’s core.


How is it constructed? 

  • Housing

  • Magnet

  • Filled with a non-freezing liquid

    • Kerosene 

  • Lubber line


Errors

Deviation – External factors from the aircraft 

  • Effects easterly and westerly direction

  • Calibration card?


Variation - Angle between TN and magnetic north (MN)

  • Earth is not uniformly magnetic

  • A correction (on the chart) to add or subtract from true to magnetic

  • Agonic line

    • Zero-degree variation

    • True north and Magnetic north are Equal



  • Errors (Magnetic Dip) {ANDS & UNOS}

    • Northerly turning errors

      • Moving in same direction (leads)

      • Under shoot

    • Southerly turning errors

      • Lags

      • Overshoot

    • Acceleration errors (East or West Headings)

      • Acceleration to the North

      • Deceleration to the South

    • Oscillation error

      • Combination of all of the other errors

      • Compass card swinging back and forth around the heading being flown





Electrical System

Equipped with:

  • 28-volt DC system

  • 60-amp alternator (Rectifies)

    • Explain how it charges the batteries

    • Regulated using ACU (Alternator Control Unit)

  • 24-volt main battery

  • 24-volt standby battery (lasts for minimum 30 min)

  • Electricity is supplied through circuits/ fuses

Essential Bus PIM Pg262:

  • PFD

  • ADC

  • Com1

  • Nav1

  • Standby indicator lights

Explain faults:

High and low volt annunciators

Checklists 





Electronic Engine Instrument Display (G1000 System)

  • Depicts engine operation

    • RPM

    • Oil pressure/temperature

    • Vacuum

    • Fuel



Primary Flight Display

  • Provides increased situational awareness (SA) to the pilot by replacing the traditional six instruments used for instrument flight with an easy-to-scan display

    • Horizon

    • Airspeed

    • Altitude

    • vertical speed

    • Trend

    • Trim

    • Rate of turn 

    • Among other key relevant indications.



Navigation equipment


Anti-ice/deicing

Deicing and anti-icing:

Talk about Icing, conditions where it may occur 

  • Anit-ice- the prevention of ice build-up

    • Heating of surfaces through bleed air or electricity

  • De-ice- is the removal of ice that has already built up

    • Inflating boots on wings

Types of anti-ice on our airplane:

  • Pitot heat

  • Cabin heat

  • Alt static source

  • Alternate air door

  • Fuel additives



Subtopic

  • Notes to self

  • Actions

Conclusion

  1. Pitot-static System

  2. Vacuum System

  3. Attitude Indicator

  4. Heading indicator

  5. Turn and slip indicator

  6. Turn Coordinator

  7. Horizontal Situation Indicator (HSI)

  8. Radio Magnetic Indicator

  9. Magnetic Compass

  10. Electrical System

  11. Electronic Engine Instrument Display

  12. Primary Flight Display

(Questions to assess student)

What is a sensitive altitude indicator?

What are some malfunctions of the pitot static system?

Electronical system?


HW: Look over flight instruments in IFH and PHAK


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