Hydraulic and Flight Controls Flashcards
EDP
Engine Driven Pump
ACMP
AC Motor Pump
Do all systems have an EDP and an ACMP?
No, only systems 1 and 2; system 3 has 2 ACMPs
What kind of pump is 1B and what powers it?
It’s an ACMP and AC BUS 2.
The EDP for system 1 is powered by what?
The left engine.
Which hydraulic reservoir is the largest?
System 3 because it services the largest demand
What is the purpose of the three accumulators in the hydraulic systems?
They help maintain a constant pressure by smoothing transient demands.
When a hydraulic SOV is closed using the L/R ENG FIRE PUSH Switchlight ____________.
The affected system can still be pressurized by a backup pressure source.
When the L HYD SOV Switchlight is pressed this advisory message is generated:
HYD SOV 1 CLSD
The EDPs normally deliver hydraulic fluid at ______ +/- _______ psi to the system’s associated hydraulically-powered systems.
3,000/200
The AC powered pumps in the hydraulic system include:
2 in system 3 1 in system 1 1 in system 2
While in the AUTO position ACMP 3B will operate automatically when an IDG is operating and:
- Flaps greater than the 0 degree position 2. An IDG is on line.
How is hydraulic system No. 3 fluid cooled?
Radiantly through fuel tanks
Which pump is primary, which pump is secondary in each system?
(A) pump = primary (B) pump = secondary
Which hydraulic system has 2 ACMPs?
3
Where are the Hydraulic shutoff valves and how many?
2; 1 in system 1, the other in system 2. They are located upstream of each EDP to prevent hydraulic fluid from reaching an engine that caught on fire.
Do the ACMPs automatically start during or after an engine failure?
Neither, they don’t automatically start.
How are the flight control surfaces controlled?
Mechanically transmitted inputs via cables and pushrods to power control units, which hydraulically position the control surfaces.
What are the primary flight controls?
Aileron, elevator, and rudder
What are the secondary flight controls?
Slats, flaps and spoiler, aileron, rudder, and horizontal stabilizer trim.
PCU
Pressure Control Units
SFECU
Slat/flap electronic control units
Purpose of SFECUs?
Controls the operation of the slats and flaps.
SSCU
Spoiler Stabilizer Control Unit
What is the purpose of the SSCUs?
Provides automatic control of spoilers, horizontal stabilizer trim, pitch feel control and the rudder travel limiter.
How many SFECUs and SSCUs?
2 of each
How many channels are the SSCUs?
Dual
What is the purpose of the artificial feel units?
Mounted on primary flight controls to help prevent excessive flight control inputs.
What’s the purpose of the flight control disconnect mechanisms?
Mounted on aileron and rudder to allow the captain or first officer to maintain aircraft control in event of a flight control jam.
To prevent agains aileron flutter in the event of hydraulic failure, what is installed?
A flutter damper by the ailerons
When and how do the spoilerons activate?
At lower airspeeds, commanded by the SSCUs which receive electrical signal from the control wheel.
Where is the autopilot roll control servo?
Only on the right aileron
Describe the aileron and spoiler on control system.
2 separate circuits, Left controlled by captain, the right by first officer. Interconnected through torque tube mechanism, which allows them to operate in conjunction with inputs.
If a jam occurs that affects roll control, what can we do?
Disconnect the torque tube by pulling and rotating the ROLL DISC handle on center pedestal
With the ROLL DISC handle pulled, how are the flight controls changed?
Each side will operate it’s own side aileron, but the opposite side spoileron.
What does pressing the ROLL SEL PLT ROLL Switchlight do and when do we press it?
Pressed when we discover which side is operable. It enables the operable sides spoilerons to be used in conjunction.
When will the white flutter damper outline appear on the FLIGHT CONTROLS synoptic page?
If low hydraulic fluid is detected in the respective aileron flutter damper.
How much hydraulic power is necessary for aileron trim to operate?
From at least one system
How many PCUs per rudder?
3, 1 from each system
How many circuits in the elevator control system and what controls what?
2 systems, Captain controls left, First officer controls right.
Are the two elevator control circuits normally interconnected? If so, through what?
Yes, through a pitch disconnect mechanism.
What should we do in the event of an elevator control jam?
Separate the left and right circuits by pulling the PITCH DISC handle and turning it 90 degrees
What side of the elevator is the autopilot connected to?
The left circuit
With the PITCH DISC handle pulled and turned, what controls the elevator?
The operable side
How is pitch trim achieved?
By adjusting the angle of incidence of the HSTAB
How is the H-STAB repositioned?
By a screw jack driven by two electric motors controlled by the SSCUs
When the autopilot is engaged, stabilizer trim is controlled ______.
Automatically
How many trim channels are there and what do they control?
2 trim channels, each one moves a separate motor that moves the screw jack up or down to change the H-STAB angle of incidence.
What does the clacker mean and when does it come on?
Runaway trim condition, comes on if trim is active for more than 3 seconds with autopilot engaged. Amber “E” will pop on PFD. Bakes on the trim motor will prevent further trim displacement.
What must be operable for Mach trim to function?
- Both SSCUs must be operable 2. At least 1 stabilizer channel
What does MACH Trim do?
Compensates for Mach Tuck’s pitch down tendency by automatically repositioning H-STAB as a function of the Mach number.
Will the Mach Trim activate when the autopilot is not engaged?
No
How are the rudder pedals moved?
Hydraulically powered by three PCUs and is mechanically controlled by rudder pedal inputs.
Are the rudder pedal circuits the same?
Yes, when rudder pedals will move simultaneously when operated from either pilot station.
What provides rudder centering?
Primary Feel Unit under first officer’s pedals
What is the purpose of the Secondary Feel Unit?
To make sure the rudder remains centered in the event of a control disconnect.
What happens if there is a rudder jam?
Rudder pedals will continue to work, but more pressure may need to be applied. This is due to anti-jam mechanisms
What is maximum rudder travel?
33 degrees
What is the Rudder Travel Limiter and it’s purpose?
Controlled by SSCUs. And reduces available rudder travel at higher airspeeds. From 33 degrees to 4 degrees
Purpose of Yaw Damp
Reduces yaw oscillations, thus preventing Dutch roll
How many Yaw Dampers?
2
How many yaw dampers need to be engaged for the autopilot system to operate?
1
How many Yaw Dampers will pushing the DISC on the Yaw Damp panel disengage?
Both
What will happen if both yaw dampers fail
- Autopilot disconnects 2. Caution appears 3. YD on PFD displays
How many slats and flaps
3 leading edge slats and 2 trailing edge flaps per wing
How are the flaps and slats controlled?
Through the SFECU and the SLATS/FLAPS lever.
What moves first during retraction, slats or flaps? Extension?
Retraction: Flaps Extension: Slats
What physically moves the slats/flaps
Dual power drive units using drive shafts, gearboxes and actuators.
If one power drive unit fails, what happens?
Slats/flaps operate at 1/2 speed, Status message
How will you know if an asymmetric flap or slat setting occurs?
Bar and position readout on synoptic page change to white and a status message appears
If the flap/slat outline on the synoptic page is purple, what does that mean?
Information is not available
What does the EMER FLAP switch do?
When positioned to DEPLOY, SFECUs override control lever selection and extend slats to 25 and flaps to 20
How many spoilers and where are they?
- Inboard/outboard multifunction spoilers Inboard/outboard ground spoilers Per wing
What do the multi-function spoilers provide?
- Aileron assisted roll control (spoileron) 2. Proportional lift dumping (flight spoilers) 3. Ground lift dumping (ground spoilers)
How are the spoilers controlled?
Via the SSCUs and hydraulically actuated by single power control unit.
Are spoilers connected to their counterpart on the other wing?
Yes, if hydraulic system failure, both would quit.
Once armed, the spoilers will automatically extend when what conditions exist:
Thrust levers are idle and at least 2 of the following: 1. L or R MLG weight on wheels switch 2. Wheel speed greater than 16 knots 3. RA<10’