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68 terms

EMB-145 Flight Controls

American Eagle EMB-145 Systems
What actuates pitch control? Trim?
Mechanically actuated elevator via fully duplicated cables, pulleys, bellcranks, and rods. Electrically actuated horizontal stabilizer.
What happens if one set of elevator (left or right) becomes jammed?
Both elevators may be disconnected by pulling the elevator disconnect handle. This will release the free elevator panel from its jammed counterpart and allow the free panel to be controlled.
How do you know the elevators have been disconnected?
An amber elevator disconnect light illuminates on the control pedestal when the elevators are disconnected.
Can the elevators be reconnected in flight?
The elevator controls cannot be reconnected in flight; maintenance action is required.
Is the stick pusher still available after elevator disconnection? Why?
The stick pusher will only be available on the left side after elevator disconnect. The autopilot servo and stick pusher servo are connected on the left side of the disconnection device.
Should the autopilot be used after elevator disconnection?
How many tabs are on the elevator? What kind are they?
There are four tabs, two on each elevator panel, located near the elevator root. The outer tabs are servo tabs. The inner tabs are spring tabs.
Describe the function of the servo tabs.
Servo tabs move in the opposite direction as the elevator to reduce pitch control forces. They move in proportion to elevator deflection.
Describe the function of the spring tabs.
Spring tabs move in the opposite direction as the elevator to reduce pitch control forces. They move in proportion to control column force. They remain in nuetral at slow airspeeds where loads are less and move at high speeds where loads are greater.
What do the tick marks on the rudder around the elevator respresent?
Each tick mark represents 2 degrees pitch. from 4 down to 10 up.
What components comprise the pitch trim system?
The Horizontal Stabilizer Control Unit (HSCU) and the Horizontal Stabilizer Actuator (HSA).
Describe the HSCU.
The HSCU has two indentical channels, a Main channel and a Backup channel. They operate independent of each other.
Describe the HSA.
The HSA consists of an electromechanical actuator driven by two DC motors. One motor is driven by the Main control channel and the other motor is driven by the Backup control channel. Only one motor is driven at a time.
What switches control the Main channel and the Backup channel?
The Main switches are on the Captain and FO control yoke. The Backup is located on the control pedestal.
What priority is given to which switches and channels?
Captain over FO, Captain and FO over autopilot. The first switch commanded between the Main and Backup switch takes precedence.
What happens if the Main and Backup switches are commanded simultaneously?
HSCU will generate an EICAS PTRIM MAIN (BACKUP) INOP warning message. Message should disappear after 4 seconds of release of second switch.
In regards to pitch trim, what does the red disconnect button on the control wheel do?
Allows disconnection from the entire pitch trim system. Red Disconnect Button must be kept pressed until Cutout button is pressed.
Maximum Airspeed after Takeoff/During Climb without Retrimming........160 KIAS
How are the ailerons actuated?
Control wheel links to torque tube and cables to provide mechanical inputs to two seperate hydraulic actuators.
Which hydraulic system powers which aileron?
Each aileron actuator is supplied by both hydraulic systems. Either system is capable of supplying full power control.
What happens if both hydraulic systems are lost?
Ailerons are actuated mechanically.
What happens if one aileron becomes jammed?
Ailerons may be disconnected via aileron disconnect handle on control pedestal.
How do you know ailerons have been disconnected?
An amber aileron disconnect light below the handle illuminates.
What is the artificial feel unit? Where is it located?
Artificial feel unit gives pilots an artificial feel of the aerodynamic load on the aileron control surface. It is on the FO (right) side of the disconnection device.
Where is the roll trim actuator located?
Right side of disconnection device.
How is roll trim performed?
By relocating the ailerons nuetral position via an electromechanical roll trim actuator.
In regards to roll trim, what does the red quick disconnect button on the control wheel do?
Disconnects the roll trim
How many rudders are there?
Two in-tandem rudders
What are the functions of the two rudders?
The forward rudder is driven by the control system. The aft rudder is linked to the forward rudder and is deflected as a function of forward rudder deflection.
Describe the rudder system schematic.
Mechanical control fully duplicated, with each set of pedals connected via cables to PCU.
What is the Power Control Unit(PCU)?
PCU is a dual hydraulic unit simultaneously powered by both hydraulic systems. Each PCU hydraulic circuit controls hydraulic power to one acutator, thus they are divided into Rudder System 1 and Rudder System 2.
What happens if both hydraulic systems are lost?
Pushing the rudder pedals mechanically postitions the rudder.
What are the two ways Rudder System 1 and/or Rudder System 2 can be automatically shut off?
Speed Switch and Rudder Hardover Protection.
Describe the rudder speed switch system.
During normal operations, both systems are powered below 135 KIAS. Rudder System 1 is automatically shut off at 135 KIAS
What happens if the speed switch system fails to shut off system 1?
An EICAS RUDDER OVERBOOST caution message is presented.
What happens to speed switch if system 2 fails?
System 1 automatically takes over the rudder an an EICAS RUDDER SYS 2 INOP caution message is presented.
What is the purpose of Rudder Hardover Protection?
To protect against a runaway rudder by automatically switching to Mechanical Reversion Mode.
When would Rudder Hardover Protection kick in?
-Rudder deflected above 5 degrees +/- 1 degree. -Force above 130 lb on the opposite rudder pedal to counteract rudder deflection. -Both engines running above 56.4% N2.
When is Rudder Hardover Protection disabled?
Single engine operation
When would you get an EICAS RUD HDOV PROTFAIL message?
-Both FADECS of the same engine disagree about the running status OR -Rudder position microswitches indicate that the rudder is deflected left and right simultaneously.
How is Yaw Trim performed?
PCU relocates the rudder's nuetral position.
In regards to yaw trim, what does the red quick disconnect button do?
Disconnects the yaw trim
Under what conditions does the Gust Lock light illuminate?
-During an unlocking cycle, -When a system failure occurs, -When it is pressed to test
What bus powers the electric gust lock system?
DC Bus 2
What is the type of flap?
Double-slotted fowler-type
What actuates the flaps?
All electric
What are the flap settings?
0, 9, 18, 22, 45.
Describe the function of the Flap Electronic Control Unit (FECU).
Sends signals for flaps to be moved, monitors system failures and flap position, and sends signals to the EICAS and other related systems.
Describe the function of the Flap Power and Drive Unit (FPDU).
It is a gearbox with two electric motors connected to it that moves the flap panels.
How many channels drive the FPDU?
Two independent channels from the FECU, one for each motor.
Which motors drive the flap panels?
Both motors
What happens if one of the motor systems fail?
The remaining motor can drive the flaps, but at half speed.
How do you know one of the motor systems has failed?
An EICAS FLAP LOW SPEED advisory message
What happens if both motor systems fail?
An EICAS FLAP FAIL caution message.
What protections are there against the flaps over torquing?
Flap actuators are torque limited to prevent excessive loads.
What protections are there against having an asymmetric panel?
Velocity sensors detect panel asymmetry. Flap system is disabled if asymmetric flaps are detected.
What happens on power up if the flaps are at zero but the flaps lever is at 9?
A protection safeguards against flap movement on power up. The lever must be lifted to overide the protection.
What subsystems make up the spoiler system?
Ground Spoiler and Speed Brake
What powers the spoiler system?
Spoilers are electrically controlled and hydraulically actuated.
How many panels make up the spoilers? What is each panels function?
Four panels. The two outboard are for speed brakes and ground spoilers. The inboard are ground spoilers only.
What is the Spoiler Control Unit (SCU)?
SCU permits ground spoilers to open or not. It automatically performs ground spoiler operation without pilot input.
When will the SCU allow the ground spoilers to open?
-Airplane on the ground, -Main landing gear wheels running above 25kts, -Both engine TLA set below 30, or both N2 below 56.4%.
When the speed brakes are commanded, what provides auto pitch trim?
When the autopilot is engaged, the autopilot provides auto pitch trim. When it is not engaged, the SCU provides auto pitch trim.
What conditions must exist for the speed brakes to open?
-Both TLA below 50, -Flaps at 0 or 9.
When would you get an EICAS SPBK LVR DISAGREE caution message?
Speed brakes commanded to open and conditions not met, or speed brakes are open, conditions are not met, and speed brakes automatically close.
How do you remove EICAS SPBK LVR DISAGREE message?
Speed brake lever must be moved to the closed position.
Maximum Altitude for Flap Extension......20,000 ft. MSL. Flaps 9, 18[135, 140] or 22[145] are the only authorized Takeoff configurations.
Maximum Airspeed after Takeoff/During Climb without Retrimming......160 KIAS