fire autopilot

autopilot purpose

guide an aircraft with minimum assistance from a pilot

why was autopilot developed

aircraft required constant attention of a pilot which lead to fatigue

autopilot function

stabilzation of flight path

single axis

aileron ROLL

two axis

aileron and elevator ROLL and PITCH

three axis

aileron, elevator, rudder ROLL, PITCH, YAW

four axis

pitch, roll, yaw, hover

controls collective pitch and hover

autonomous autopilot modern fixed wing

pitch, roll, yaw, auto-throttle

controls power for fully automated flight and landing capabilities

operation of landing gear, flaps, brakes, engine shutdown

what is the heart of a modern automatic flight control system

computer

computer purpose

gathers all details required to control the plane from sensors and other systems

what controls the autopilot system

autopilot hydraulic unit or mechanical units

autopilot operation

turn heading selection knob or VOR course > aircraft follows commanded action without needing to move the controls

modes

HDG

NAV

ILS

altitude hold

HDG

selected heading acquisition and hold

NAV

navigation course capture and tracking

ILS

landing guidance, localizer and glideslope

altitude hold

maintain altitude by manipulating pitch servos or cables

autopilot uses ______ feedback loop to reach its objectives

negative

control systems apply an action based on _____

measurement

autopilot status info is displayed on

display crew alerting system (DCAS)

B787 autoflight system consists of

• Flight management function (FMF)

• Autoflight function (AFF)

• Thrust Management Function (TMF)

AFF consists of

autopilot and flight director

AFF operation

uses commands from FMF or flight crew can use the mode control panel to control the aircraft

TMF purpose

controls engine thrust levers

TMF operation

FMF sends thrust and speed targets to TMF

B787 autoflight operation

flight crew enters route and performance data into CDU > FMF calculates lateral and vertical components of the flight > FMF sends guidance commands to AFF to follow the flight plan

yaw damper

Receives aircraft movement info from accelerometers or rate sensors in the rudder > translates to the proper amount of calming rudder inputs

yaw damper on single engine

Smooths out left-right movements of vertical stab (fishtailing)

yaw damper on swept wing

prevents dutch roll tendency

dutch roll

yaw and roll of wing

mach trim

Device that varies pitch trim automatically to oppose Mach tuck and maintain level flight

mach tuck

As aircraft approaches transonic flight and into supersonic flight > center of pressure moves aft along the chord line of the wing > center of gravity is forward of center of pressure > causes nose to pitch down

where are mach trims installed on

hydro-mechanical flight controls

flight director purpose

tells pilot where they are to fly on course

flight director is linked with

nav system, FMS or autopilot

CDU

control display unit

CDU located

forward portion of center pedestal

CDU purpose

pilots enter flight information

autopilot operation

1. Autopilot computer sends signal to the servos that control ailerons

2. Signal is a specific command telling the servo to make a precise adjustment

3. Each servo has a small electric motor fitted with a slip clutch that grips the aileron cable through a bridle cable

4. Cable move > control surface move

5. Ailerons are adjusted based on the input data and then the wings move back toward level

6. Autopilot computer removes the command when the position sensor on the wing detects the wings are level

7. Servos stop applying pressure on aileron cables