Flight Controls Flashcards
How do the stabilizer position indication and green band function?
Green and indicates the allowable takeoff trim range, based on gross weight, takeoff trust, v1 and CG information from the FMC.
No V1 or information available, green band defaults to midrange
If the stabilizer signal is not present or is invalid, the green band and pointer are not displayed
STAB GREENBAND advisory message (amber) indicates the nose gear pressure switch disagrees with the computer stabilizer greenband
What flight controls are available in the event of a complete electrical system shutdown?
Cables to spoilers 4 and 11 and Stabilizer
What are the flap/slat modes of operation and the protections available in each mode?
Primary (hydraulic) Flap load relief, auto slats asymmetry protection and uncommanded motion
Secondary (electric) Slat load relief, Asyetry Protection and uncommanded motion
Alternate (electric) manual operation with no protections
What does pitch trim on the control wheel move on the ground and in flight in normal, secondary and direct modes?
On the ground it move the stabilizer
In flight it changes the trim reference speed
In secondary and direct modes it moves the stabilizer
The trim green band range is based on what?
Gross WT, takeoff thrust and V1, and CG from the FMC
What do the three ranges on the green trim indication represent?
• the mid-band
• the nose down band (which includes the mid-band)
• the nose up band (which includes the mid-band).
How is the trim range (green band) crossed checked?
A nose gear oleo pressure switch provides an automatic cross–check of the CG to
ensure that the correct green band has been selected
9.20.14
When the STAB trim cutout switches are in the normal mode, how are they operated and if that system fails what happens automatically?
Hydraulically operated by the RT and CRT system
If uncomanded movement is detected it will automatically cutoff the center and right hydraulic system
Flap handle operates in which modes and what system?
Primary mode = hydraulically operated
Secondary mode = Electrically operated
What protections are not available in the alternate flap mode?
Asymmetry protection
Load relif
Auto slats
Screw and uncommanded motion
What rang is the alternate flaps limited too?
Flaps at 20
Slats at mid-range
What are the systems that the PFC gets it information from?
Air data
Inertial data
Flap and slat position
Engine thrust
Radio altitude
How do flapperons function?
They droop with flaps for increase lift
How do flapperons function?
They droop with flaps for increase lift
When do ailerons droop and why?
They move down at flaps 5, 15, 20 (takeoff flap settings)
To improve takeoff performance
Which flight controls are locked out during high-speed flight?
Out board ailerons and spoilers 5 and 10
When does the PFC begin their self-test?
2 mins after the ECAS message HYD PRESS SYS L+C+R is displayed
Normal Mode
What are the flight envelope protection and how are they communicated to the pilot?
Stall protection
Overspeed protection
Bank angle protection
TAC (thrust asymmetry compensation)
Autopilot
Gus suppression
Wheel cross-tie
Auto brakes
Rudder cancel
Tailstrike protection
Yaw dampening
They are communicated by:
Sight- visual cues
Sound- Aural
Feel- Tactile
Secondary mode
What is the different about the PFC in Secondary mode?
Simplified control laws, as a result the elevator and rudder are more sensitive at some airspeeds
What functions are not available in flight control secondary mode?
Autopilot
Auto speed brakes
Thrust asymmetry compensation (TAC)
Gus suppression
Envelope protection
Tail strike protection
Yaw damping ( degraded or inoperative)
What is different in direct mode?
PFC’s are off
Manual rudder trim cancel switch is not availible
How is direct mode the same as secondary mode?
Full airplane control for safety of flight and handing
Angling qualities are approximately the same as secondary mode
Which flight controls have a mechanical back up?
Stabilizers
Spoilers 4 and 11
Normal mode, pitch control
How is the elevator controlled?
The control column commands the PFC to generate a pitch maneuver
The PFC automatically moves the stabilizer and elevators
What pitch changes will the PFC accomplish automatically?
Thrust changes
Gear configuration
Turbulence
Flap and speed brake configuration
Bank up to 30degrees
During manual landing the PFC commands a slight nose down pitch (so the pilot can have a normal feel on landing and make normal in puts)
When is pitch trim switches inhibited?
When the autopilot is on
Dose the pitch trim move the control column?
NO
How does the PFC trim the aircraft when the pilot inputs a trim command?
It moves the elevator first then the stabilizer to streamline the elevator
How do the alternate pitch trim operate in the normal mode?
Moves the trim reference speed
How is the alternate pitch trim connected to the stabilizer?
Cables from the lever to the stabilizer trim control modules (STCM) then mechanically to the stabilizer
Which pitch trim, control column or alternate has priority in all flight modes?
Alternate pitch trim
What can the alternate pitch trim levers do and not do?
They WILL NOT disengage the autopilot, BUT WILL move the stabilizer
They WILL NOT remove column pressure during a stall or overspeed protection, BUT WILL move the stabilizer
Should the alternate pitch trim levers be used when the autopilot is on or during a stall or overspeed protection?
NO!!
How does stall protection work?
Trim is limited in the nose up direction
By limiting the trim reference speed to not exceed the critical angle of attack (top of amber band)
NOTE: at high ALT this could be 10 to 20kts lower than the top of the amber band.
How does overspeed work?
Trim is inhibited in the nose down direction
By limiting the speed at which the airplane can be trimmed, at Vmo and Mmo
How does tail strike protection work?
The PFC automatically calculates if a tail strike is imminent and decreases elevation deflection….there is not feed back to the control column of this happening
Which pitch compensation are not available in the secondary and direct modes?
Thrust changes
Bank angle
Gear configuration
Flap and speedbrake configuration
Turbulence
What do the trim switches and alternate trim levers control in secondary and direct modes?
Stabilizer directly
There is no trim reference speed
In regard to the stabilizer, what does STCM stand for?
Stabilizer Trim Control Module
How many STCM are there?
2, one connected to each stabilizer
How does the STCM control the stabilizer?
It controls hydraulic power to the stabilizer
Center and right are hydraulic sources to the STCM
How is uncommanded motion of the stabilizer stoped?
The Failed STCM is shut off
The remaining STCM operates both stabilizer
The EICAS message STABILIZER come on for 2 reasons?
- Both STCM’s have failed
- If automatic shut down failed to stop the uncommanded motion
