11.05.2 Autoflight Flashcards
What are the autoflight subsystems? (5)
- Autopilot (AP),
- Flight Director (FD)
- Auto throttle System (ATS)
- Automatic pitch trim system (auto trim),
- Yaw Damper System (YD).
What is the primary task of autoflight?
reduces the pilot’s workload by controlling the flight automatically
What does flight director do?
shows the pilot how to fly the aircraft manually using the
command bars in the Primary Flight Display (PFD) or Attitude Director Indicator (ADI).
What does yaw damper do?
- improves the dynamic stability of the aircraft during the whole flight
- controls the rudder to dampen Dutch roll oscillations during the entire flight.
What does autotrim do?
maintains pitch stability during all phases of the flight, usually by automatically adjusting the horizontal stabilizer
What are the three aircraft axes?
- the longitudinal, X-axis
- the vertical, Z-axis
- and the lateral, Y-axis
What flying control surfaces are used to control pitch?
Horizontal stab (pitch trim) and elevator
What flying control surfaces are used to control roll?
Ailerons and flight spoilers
What flying control surfaces are used to control yaw?
Rudder
What are aircraft with electronic AP systems called?
EFCS systems
What are the two loops of autoflight called?
- inner loop
- outer loop
What two channels are used in the inner loop for autoflight?
- pitch channel
- roll channel
What does the autoflight inner loop control?
Aircraft attitude
How does the autoflight inner loop control aircraft attitude?
- the comparison between the actual attitude of the aircraft and the commanded attitude.
- The result of the comparison is called the ‘attitude error signal’
- this basically drives the flight control surfaces
Where are autopilot inner loop actual attitude signals from?
from the aircraft’s attitude sensors (vertical gyro or the
IRU)
Where are autopilot inner loop commanded attitude signals from?
comes from selections made by the pilot or from the
outer loop
What does the autopilot outer loop control?
The outer loop controls the aircraft to automatically capture and stabilize a flight path
How does the autoflight outer loop control aircraft flight path?
- comparison between a commanded value (the desired path) and the actual flight path.
- The result of the comparison is called the ‘path error signal’
- this is converted by the autopilot to the attitude command signal for the inner loop
What angle is roll attitude limited to in autoflight?
30 degrees
What angle is pitch angle limited to in autoflight?
25 degrees nose up and 10 degrees nose down
How many autopilots are used during cruise?
Only one at a time during normal flight
What are the three AP engage selections?
- OFF - The autopilot is not connected to the flight controls.
- CMD - Command position engages the autopilot for automatic flight, using the calculated signals from the inner and outer loops.
- CWS - The Control Wheel Steering position (middle) activates the CWS function and only the inner loop of the autopilot is active to control the aircraft attitude. The pilot uses the control wheel or column to change the attitude
What is the difference between the CMD and CWS selections?
- CMD uses both inner and outer loops
- CWS just uses inner loop
How is autopilot disengaged?
The autopilot can be disengaged on the control panel by pressing the ‘disengage bar’ or by moving the autopilot lever to off.
Normally the autopilot is disengaged by pressing the red quick disengage pushbutton located on each control wheel.