Transcript Review 3 PowerPoint

Systems Review 3
ATC Chapter 4
Aim
To review principals of operation of pressure,
gyroscopic and electrical instruments
Objectives
1. State what each instrument indicates and name
the power source for each instrument
2. State the effect of system failures on instrument
indications
1. Instruments indications and source
Artificial Horizon (AH or AI)
Sometimes referred to as the master instrument
Indicates both pitch and bank attitude directly (in miniature) against the
artificial horizon
Miniaturization of the outside world
means that small movements of the AH
represent quite large changes in pitch and
bank attitudes
Indirectly, the AH is a guide to airspeed
• Nose low, high or increasing airspeed
• Nose high, low or decreasing airspeed
Most commonly driven by an engine
driven vacuum pump but can be
electrically driven or venturi driven
1. Instruments indications and source
Airspeed indicator (ASI)
Directly indicates the aircrafts speed through the air by measuring the
difference between total pressure from the Pitot tube and the static
pressure from the static source
Total pressure – Static pressure =
Dynamic pressure
Indirectly indicates the pitch attitude
of the aircraft
• Low or decreasing airspeed, nose
high
• High or increasing airspeed, nose
low
The ASI is driven by the Pitot static
system and requires both dynamic and
static pressure.
1. Instruments indications and source
Altimeter
Directly indicates the aircrafts height above a datum
In Australia below 10,000ft AMSL seal level is set as the datum
Indirectly indicates pitch attitude
• Altitude decreasing, nose low
• Altitude increasing, nose high
The altimeter is driven by the aircrafts
static vent
1. Instruments indications and source
Altimeter – Incorrect subscale settings
Below 5,000ft every 1 hPa that the altimeter is in error is equal to 30ft
error displayed on the altimeter
If the subscale is set too low the altimeter will read low
If the subscale is set too high the altimeter will read high
1. Instruments indications and source
Vertical Speed Indicator (VSI)
Directly indicates the rate of change of altitude.
Indirectly it indicates pitch attitude
• VSI decreasing, nose low
• VSI increasing, nose high
Useful as a trend indicator
The vertical speed indicator is driven by
the aircrafts static vent
1. Instruments indications and source
Heading Indicator
Allows direct reading of heading
Can be a Direction Gyro (DG) or Horizontal Situation Indicator (HSI)
DG must be manually aligned with
aircraft compass. HSI automatically
aligns with the Earths magnetic
field
Indirectly it indicates Bank angle
• HSI decreasing, left turn
• HSI increasing, right turn
Electronically driven or driven by
vacuum pump
1. Instruments indications and source
Turn Coordinator (TC)
Directly indicates the rate of change of direction
Indirectly it can indicate limited angles of bank usually to 35 degrees
Usually powered by an electrically driven Gyro.
1. Instruments indications and source
3. Instrument Indications
Balance Indicator
Directly indicates balance
Usually incorporated with the turn co-ordinator
Indirectly indicates aircraft yaw
Powered by gravity
Slipping Turn
Skidding Turn
Co-ordinated Turn
1. Instruments indications and source
Tachometer
Directly indicates engine RPM
Indirectly indicates pitch in aircraft without a CSU
• Increase RPM, nose low
• Decrease RPM, nose high
Driven by the engine via mechanical linkage
1. Instruments indications and source
Magnetic Compass
Allows direct reading of heading
Primary navigation aid for most light aircraft
Indirectly it indicates Bank angle
• Compass decreasing, left turn
• Compass increasing, right turn
Susceptible to a number of errors
1. Instruments indications and source
Magnetic Compass
Reading the compass
When we look at the compass we are reading the back of it. This means the compass
in our aircraft reads backwards
This is best shown on a boat compass. If we are heading 300 and
wanted to turn onto 270 we know the shortest turn will be to the
left.
When we are looking top
down on the compass we
can see 270 is to the left
of 300. However when
we look at the front of
the compass card 270 is
to the right of 300
1. Instruments indications and source
Magnetic Compass
Variation
Angular difference between true north and magnetic north
The magnet in the compass aligns itself with the earths lines of magnetic
flux (magnetic north)
1. Instruments indications and source
Magnetic Compass
Deviation
Occurs when the compass magnet is acted upon by a magnetic field other
than the Earths. Can be caused by electronic or metal objects near the
compass.
The error is displayed on a compass deviation card produced by an engineer
after they carry out a compass swing
1. Instruments indications and source
Magnetic Compass
Dip
At the equator the earths magnetic field is parallel with the earths surface,
the magnetic bar of the compass also lies parallel with the Earths surface
1. Instruments indications and source
Magnetic Compass
Dip
As you travel closer to the poles the lines of magnetic flux begin to dip, so to
does the magnetic bar of the compass
To help reduce this error the compass magnet is suspended from a pivot point.
This now means the center of gravity of the compass magnet is always going
to be displaced from the pivot point
1. Instruments indications and source
Magnetic Compass
Turning Errors
Because the center of gravity of the magnet is displaced from the pivot point,
when we Bank the aircraft there is a horizontal component of gravity that acts
on the compass resulting in a change of heading indicated
This error is maximum on North and South, nil on
East or West
To remember which way it will rotate we use the
acronym ONUS
O
N
U
S
vershoot
orth
ndershoot
outh
1. Instruments indications and source
Magnetic Compass
Acceleration Errors
Because the center of gravity of the magnet is displaced from the pivot point,
when we accelerate or decelerate the compass will lag behind the aircraft and
will rotate. This error is maximum on East or West, nil on North or South
When we accelerate the compass will swing towards the south, when we
decelerate the compass will swing towards the north
To remember which way it will rotate we use the
acronym SAND
S
A
N
D
outh
ccelerate
orth
ecelerate
1. Instruments indications and source
G1000
Directly indicates all of the above parameters
Information is generated by the air data computer, AHRS and magnetometer
All indications are displayed
on the PFD and MFD
2. System failures
Vacuum Failure
Instruments affected
• Artificial horizon
• Direction Gyro
Indicated by:
• low VAC pressure reading
• Annunciator
Troubleshooted by:
• Can get false indications at low RPM
2. System failures
Vacuum Failure
Artificial Horizon
Failure indicted by:
• The gyro toppling, may happen over an
extended period of time as the gyro slows down
• Red warning flag
Direction Gyro
Failure indicted by:
• Red warning flag
• Inaccurate readings, check against compass
2. System failures
Pitot Static System
2. System failures
Pitot Blockage
Instruments affected
• Airspeed indicator
Indicated by:
• No airspeed increase during takeoff roll
Troubleshooted by:
• If failure is identified during the takeoff roll abort the takeoff if it is safe to
do so
• If failure occurs airborne Pitot heat may be required, refer to flight manual
2. System failures
Pitot Blockage
Airspeed Indicator
Failure indicted by:
• No airspeed increase during take off roll
• If Pitot tube blockage occurs during
flight the ASI is only read correctly at
blockage altitude
- If aircraft climbs above blockage
height ASI over-reads
- If aircraft descends below blockage height ASI under-reads
2. System failures
Static Blockage
Instruments affected
• Airspeed indicator
• Altimeter
• Vertical speed indicator
Indicated by:
• ASI over or under reading
• Altimeter not increasing with an increase in altitude
• VSI reading zero with an increase in altitude
Troubleshooted by:
• Alternate static source may be required, refer to flight manual
2. System failures
Static Blockage
Airspeed Indicator
Failure indicted by:
• If static source blockage occurs
during flight the ASI is only correct
at blockage altitude
- If aircraft climbs above
blockage height ASI underreads
- If aircraft descends below
blockage height ASI over-reads
2. System failures
Static Blockage
Altimeter
Failure indicted by:
• Will continue to read blockage altitude
with an increase or decrease in altitude
Vertical Speed Indicator
Failure indicted by:
• Will continue to read zero with
an increase or decrease in
altitude
2. System failures
Electrical Failure
Instruments affected
• G1000
• Turn coordinator
Indicated by:
•
•
•
•
•
Very high voltage reading
Very low voltage reading
Very high amp reading
Very low amp reading
Annunciator
Troubleshooted by:
• Depends on indication,
refer to flight manual
2. System failures
Electrical Failure
G1000
Failure indicted by:
• Red X through affected instruments
• If complete failure occurs the screens
may cease to function
Turn coordinator
Failure indicted by:
• Red warning flag
Note: The balance ball will still be functional
Questions?