Chapter 8: Flight Controls Flashcards
Primary Flight Controls
- Ailerons
- Multi-function spoilers (used for roll control)
- Elevators
- Rudder
Secondary Flight Controls
- Horizontal Stabilizer
- Flaps and Slats
- Multi-function spoilers (used as speed brakes)
- Ground spoilers
Fly-by-wire Control Surfaces
Everything but the ailerons
Pitch Trim Switch Limits
- Both sides must be pressed to actuate
- If only half is pressed for more than 5 seconds, switch is disabled
- Movement limited to 3 seconds
- “PITCH TRIM FAIL” EICAS message if AP/TRIM DISC button held for more than 11 seconds
Slat/Flap Positions vs. Lever Position
Lever Slat Flap 0 0 0 1 15 5 2 15 10 3 15 20 4 25 20 5 25 20 Full 25 35
PITCH TRIM SYS 1(2) CUTOUT Button
(1) : De-activates HS-ACE channel 1 and the PITCH TRIM DISC function of the CA’s AP/TRIM DISC button
(2) : De-activates HS-ACE channel 2 and the PITCH TRIM DISC function of the FO’s AP/TRIM DISC button
Can be cycled to reactivate a disabled trim switch
Fly-by-Wire Components
- Three (3) Primary ACEs (P-ACE)
- Two (2) Slat/Flap ACEs (SF-ACE)
- One (1) Horizontal Stabilizer ACE (HS-ACE)
- Three (3) Spoiler ACEs (S-ACE)
- Four (4) Flight Control Modules (FCM)
Actuator Control Electronics (ACE)
Connect flight control electronically to the control surface, providing direct analog control
Primary Control Electronics (P-ACE)
Active-Standby configuration
Three (3) total, Two (2) in Forward E-Bay, one (1) in aft E-Bay
Flat/Flap Actuator Control Electronics (SF-ACE)
Each SF-ACE has two channels, one for flaps, one for slats
Two (2) units, middle E-Bay
Horizontal Stabilizer Actuator Control Electronics (HS-ACE)
One (1) unit, two (2) channels in active/standby configuration, changes daily
Installed in aft E-Bay
Spoiler Actuation Control Electronics (S-ACE)
Three (3) S-ACEs, reside in FCMs 1, 3, and 4
Each S-ACE controls a MF-spoiler pair
Flight Control Modules
Four (4) Flight Control Modules.
FCM 1 and 2 are located in MAU 1
FCM 3 and 4 are located in MAU 3
Provide software-based assistance to P-ACEs through the CAN BUS
Higher Level Functions
- Elevator gain w/ airspeed
- Auto-thrust compensation with elevator
- AOA limiting with elevator offset
- Rudder gain w/ airspeed and stroke limiting
- Yaw damper and turn coordination
- Rudder flight authority
- Roll Spoiler gain w/ airspeed
- Configuration change compensation with horizontal stabilizer due to speed brake actuation
CAN BUS and ASCB
CAN BUS (Controller Area Network) -Provides communication between FCMs and P-ACEs
ASCB (Avionics Standard Communications Bus)
-Provides data exchange between FCMs and other avionics components
Electrical PBIT
- Initiated automatically after being powered by an AC source
- Takes 3 minutes to complete
- Interrupted if a hydraulic pump is turned on, AC power is interrupted, or FCP switches are cycled
Hydraulic PBIT
- Runs when all 3 hydraulic systems are pressurized
- Takes 1 minute
- Cancelled if flight controls are moved or hydraulic pumps turned off
Fly By Wire (FBW) Backup Battery
- Keeps the proper number of elevator and rudder actuators operating for at least 15 minutes
- Lead acid battery charged by DC ESS BUS 3
Elevator Control
- Two (2) PCUs on each elevator, active-standby configuration
- Two (2) LVDTs on each control column, providing redundant analog signal to on-side P-ACE channels
- Two (2) artificial feel units, pre-loaded spring attached to each torque tube
L,OB Elevator Hyd 1 P-ACE 1-1 FCM 1A, 4B
L,IB Elevator Hyd 2 P-ACE 2-1 FCM 2A, 3B
R,IB Elevator Hyd 2 P-ACE 2-2 FCM 2B, 3A
R,OB Elevator Hyd 3 P-ACE 3-1 FCM 1B, 4A
Horizontal Stabilizer Control
- One (1) dual channel HS-ACE, active-standby configuration
- Two (2) DC motors in active/standby configuration
- One (1) Horizontal Stabilizer Actuator (HSA)
HS-ACE input priority:
- Backup Trim Switch - CA Trim Switch - FO Trim Switch - FCM
- Will ignore trim up commands if stick shaker is activated
- Only HS-ACE Channel 2 is active during electrical emergency at low rate
- Loss of FCM data => low rate operation
Roll Control
- Conventional cable system
- Two (2) PCUs per aileron, load-sharing
- Hydraulic system 2 powers inboard PCUs
- Hydraulic system 3 powers outboard PCUs
- CA commands MF-spoilers L5, R5
- FO commands MF-spoilers L4, R4
- Artificial feel unit on CA’s side
Multi-Function Spoiler Control (Roll)
- Normal Mode: Spoiler deflection is reduced with increasing airspeed
- Direct Mode: If FCM/S-ACE failure, only the affected spoilers revert to direct mode
- Hydraulic System 1 powers L3/R3 and L4/R4
- Hydraulic System 2 powers L5/R5
Rudder Control
- Two PCUs, active-standby configuration, (Odd-Even Day)
- CA controls upper PCU, FO controls lower PCU
- LVDT’s from rudder pedals send analog signal to respective P-ACE
Lower Rudder Hyd 3 P-ACE 3-2
Upper Rudder Hyd 1 P-ACE 1-2
- Direct Mode: 1 of 2 Fixed Gain’s
- Low Speed: Flaps extended, maximum authority
- High Speed: Flaps retracted, structural protection
Slat/Flap Control
- Slat/Flap lever sends signal to both SF-ACEs
- Channel 1 controls flaps, channel 2 controls slats
- Slat PDU powers all 8 slat panels via torque tubes (4 panels per side)
- Flap PDU powers all 8 flap actuators (4 actuators per side)
