Flight Controls Flashcards
What physically actuates the flight control surfaces?
Power Control Unit (PCUs)
What are the primary flight controls?
- Ailerons and MFS for roll
- Elevator
- Rudder
What are the secondary flight controls?
- Horizontal Stabilizer
- Flaps and Slats
- MFS
- Ground Spoilers
Does the CA’s pitch trim have priority over the F/O?
Yes
Manual pitch trim commands are limited to how many seconds?
3 seconds
After pressing and holding the AP/Trim Disc, will releasing the AP/TRIM Disconnect Button reactivate any active trim commands?
Yes
When the AP/TRIM Disconnect Button is pressed what channels are deactivated?
Will disconnect ALL trim functions so long as you have the AP/DISC button depressed
What does pressing one of the 3 Flight Control mode Panel buttons do?
Brings the respective flight control into Direct Mode
What are the 2 flight control modes?
- Normal Mode
- Direct Mode
What are the 3 Flight Control Mode Buttons?
- Elevators
- Rudders
- Spoilers
What happens when you pull the elevator disconnect handle?
Isolates CA and FO control columns for elevator control
What happens when you pull the aileron disconnect handle?
isolates the Captain and First Officer’s control wheel for aileron control
How many ACEs and FCMs are on the 175?
9 Actuator Control Electronics
4 Flight Control Modules
How many P-ACEs are there?
3 Primary Actuator Control Electronics (2 FWD E-Bay; 1 AFT E-Bay) and control Elevator and Rudders
Each has 2 channels (active and standby)
There are how many SF-ACEs (slat/flap)
2 SF ACEs located in the Mid E-Bay (1 for slat; 1 for flaps)
Where is the 1 HS-ACE located?
AFT E-Bay
Where are the S-ACEs (spoilers)?
They are located within FCM #1, FCM #3, FCM #4 which have wiring to control the S-ACEs
Where is FCMs 1 & 2 located?
MAU 1 in the FWD E-Bay
Where is FCM 3 and 4 located?
MAU 3 in Mid E-Bay
How are the P-ACEs connected to the FCMs?
FCMs are connected to Controller Area Network Bus (CAN BUS) to provide inputs to 3 P-ACEs
What happens to the system logic when you go into Direct Mode?
FCMs are removed from the control loop
Which are some of the way the flight controls can go into Direct Mode?
- Automatic detection of channel failure
- Manually selected on Flight Controls Mode Panel
- Loss of Airspeed Data
The ____ is the communication link between the FCMs and the P-ACEs
Controller Area Network Bus (CAN BUS)
What provides data exchange between all FCMs, and with other components of the avionic system?
Avionics Standard Communication Bus (ASCB)
Which 2 systems have Power-Up Built in Tests (PBITs)?
- Electrical
- Hydraulic
The electrical PBIT is performed when and how long to complete?
Anytime during power up after AC power is given to the aircraft and takes 3 mins to complete
The hydraulic PBIT takes how long to complete, and requires what to perform test?
About 1 min and all 3 HYD systems pressurized with no fluid temp below 50º F or 10ºC
How long does the FBW back up battery last?
15 mins and is charged by DC ESS Bus 3
What are the 3 higher level functions for pitch control?
- Gain on airspeed
- Elevator Thrust Compensation
- AoA Limiting
What actuator controls pitch trim?
HS-ACE communicates to 2 DC electric trim motors (active/stby motors) that drive the HSA, Horizontal Stab. Actuator
Pitch Trim Priority?
- Back-Up Trim
- CA trim
- FO trim
- AP trim
Will speed brakes/spoilers work in Direct Mode?
No
What type of flaps does the 175 use?
Double-slotted fowler flaps
How many slats per wing?
4 total and only outboards (2,3,4) receive wing A/I
What is the path from S/F Lever to S/F surface?
Slat/Flap Lever > (2) SF-ACE > PDU > Flap Surface
What is the path from control wheel to aileron surface?
Control wheel > PCU > Aileron surface
What is the path from control wheel to elevator?
Control wheel > ACE with FCM input > PCU > Elevator surface
What is the path from trim to Hzt. Stab.?
Trim priority > ACE with FCM input > DC electric trim motor > HSA > HZT Stab
What is the path from rudder pedals to rudder surface?
Rudder pedals > ACE with FCM inputs > PCU > Rudder surface
With RAT deployed, how do the Slats/Flaps operate?
Half-speed and only down to Flaps 3 to maintain adequate speed for RAT electrical generation
What are the 3 functions of the MFS (3,4,5)?
- Speed brakes (6 MFSs to 30º)
- Roll control
- Ground spoilers (MFSs 40º and GSs 60º)
When will the spoilers (1-5) auto deploy?
Auto deploy
1. WOW
2. Wheel Speed > 45 kts or AS > 60 kts
3. TLA < 26º
When do the speed brakes (3,4,5) auto retract in flight?
- S/F of 2 or greater
- Airspeed < 180 kts
- TLA > 70º
What is the max rudder deflection?
30º either direction
Which HS-ACE channel is active during an electrical emergency?
Channel 2 (DC ESS) at low rate
What are the high level functions (FCM) for the rudder?
- Yaw Damp
- Turn Coordination
- Gain on airspeed
What deploys first and retracts first, slats or flaps?
Slats deploy first, flaps retract first (S/F)
How many S/F positions are there?
7 positions (0 to FULL)
What happens to artificial feel if flight controls are disconnected?
Artificial feel is felt at 1/2 the normal load
How are the flight controls trimmed?
Roll and Yaw = Surface repositioned to a new “neutral position”
Will the multi-function spoilers function in Direct Mode?
Yes, for roll only and at a default fixed gain
How do the flight controls operate when the RAT is the only AC Power?
- HS trim operates at LO SPEED
- S/F System operates at LO SPEED
- S/F Position is limited to 3
Right aileron becomes jammed, what are you left with for roll control?
- FO aileron control is lost
- CA side retains roll control of the left aileron and MFS #5 with normal AFU
Left aileron becomes jammed, what are you left with for roll control?
- CA’s half of the system is jammed.
- The First Officer retains control of the right aileron with artificial feel created by a bungee system but roll trim is not available. The pair #4 of multi-function spoilers will remain available.
What happens if the rudder pedals are jammed?
Rudder control is maintained through the YD and turn coordination (FCM functions)
What happens if the rudder PCU (actuator) is jammed?
Rudder will be hydraulically locked at the current position. Aircraft control will be established through the ailerons and roll spoilers
When will the MFSs auto retract on the ground?
Auto retract
1. Wheel speed < 45 kts
2. TLA moved beyond 35º after landing (GA scenario)
How do you know if you have a flight control problem like a jammed actuator?
The Flight Controls Synoptic Page (flight control will be yellow)
Can the Flight Controls be reconnected after pulling red Disconnect Handles?
Nope
