Flight Control Flashcards
How many flap control units are there?
3 FCU’s
What are the basic functions of the FCU’s
Primary control
Secondary control
Indication and annunciation
(Flap lever transmitted to FCU, sequences movement and monitors operation)
How are groups of leading flaps provided, and normally powered?
- Inboard
- Midspan
- outboard
Pneumatic powered by associated L&R pneumatic system.
Back up is elec motor much slower
What are two groups of TE flaps, how are they powered?
Inboard TE flaps - HYD sys 1
Outboard TE flaps - HYD sys 4
Mechanically connected to assure symmetry
Can also be electrically driven slower
How are opposite trailing edge flaps connected?
Mechanically to assure symmetry
What protection features do FCU’s provide for trailing edge flaps in primary mode?
Flap sequencing
Trailing edge asymmetry
Flap disagreement
Un commanded motion protection
Flap load relief
Flap position to EICAS and other sys
What protection features do FCU’s provide for trailing edge flaps in secondary mode?
Flap sequencing
Trailing edge asymmetry
Flap disagreement
Uncommanded motion protection
Flap position to EICAS and other sys
Function of FCU’s in primary mode
Drive LE flaps pneumatically and TE flaps hydraulically
Function of FCU’s in primary mode
Drive affected flaps through an electric motor
What happens if primary control failure in inboard or midspan LE flap group?
Failure in either group switches both groups to Secondary mode on both wings
What happens if a failure occurs in a leading edge flap group on one wing?
It’s symmetric flap group on the other wing switches to secondary mode as well
What happens immediately if a trailing edge asymmetry is detected?
- Primary mode operation is shut down for asymmetric group
- FCU’s do not switch to secondary mode
What EICAS advisory message displays if all three FCU’s fail in their control function
FLAPS CONTROL - with beeper
How does Flap Alternate Control mode work?
- ALT FLAPS selector moved to EXT
- all LE and TE flap groups begin extending immediately
- Max position flaps 25
Any asymmetry protection in alt flap mode?
No
State the actions that occur when ALTN Flaps Arm switch is pushed
Bypasses all three FCU’s
Shuts off primary and secondary mode
Arms the alt flap control
FLAPS CONTROL Eicas
- flap lever inop
- LE and TE driven electrically by ALTN FLAPS selector
Max extension of TE flaps in alternate mode?
Flaps 25
Describe secondary mode or non normal expanded flap position indication for LE Flaps
On Expanded display
3 boxes on each wing (6 total) indicate outboard, inboard and midspan separately
Describe the secondary mode or non-normal expanded flap position indication for trailing edge flaps
On expanded display two vertical indicators (white bars) for each wing indicate the outboard and inboard TE Flaps.
Green line with associated flap setting indicates flap lever position
Vertical bar (outlined in white) fills solid white to represent flap position
What does an amber X mean on an expanded flap display?
Position sensor for respective flap has failed
Operate normally unless FLAPS CONTROL, FLAPS DRIVE or FLAPS PRIMARY Eicas message is displayed
If Stby bus is only powered AC bus the L wing trailing edge flap sensors are not powered
Describe the alternate mode expanded flap position indicator
- The position of each flap group is separately indicated
- Flap lever position (green line) not displayed
- position index marks at flaps 5 and flaps 25
Describe the flap position indication on EICAS if the standby bus is the only powered AC bus
Expanded display with an amber x in the amber outlined L wing TE flap indications
What flaps extend when the flap lever is moved from up to flaps 1
Onboard and mid span LE flaps only
What flaps extend when the flap lever is moved from flaps 1 to flaps 5
Outboard LE, TE to position 5
What flaps sequencing occurs when using alternate flaps?
EXT:
- All LE and TE Flaps begin extending immediately
- TE flaps extend to max 25
RET:
- TE flaps retract first then LE flaps
(No asym protection)
Describe flap load relief
- only in primary mode
- 25 or 30 max flap speed exceeded auto system relieves to 25 or 20
- flap lever does not move
- EICAS message FLAP RELIEF
- automatic extend back after slowing
- not available in secondary or alternate
How long does the flap indication on the primary Eicas reman displayed after all flaps are up?
10 sec
What is the effect on the flap system during engine reverse thrust operation
Auto retraction of midspan and inboard LE flaps occurs
(POS indicator reflect flaps in transit)
Describe function of STAB trim cutout switches, AUTO
Hydraulic pressure normally applied to associated system if I commanded trim detected associated hydraulic power automatically cutout
EICAS - STAB TRIM 2 or 3
What surface component is moved when stab trim inputs are made
Horizontal stabilizer to vary the angle of incidence (sys 2&3)
State what occurs when the stabilizer trim cutout switches are in CUTOUT
Manually deactivates the hydraulic power to the Stab Trim Control Module (STCM)
will cause stab trim 2 or stab trim 3 to display
Describe the function of the alternate trim switches
ALTN STAB TRIM - alt means to signal both STCM’s simultaneously
- not routed through control column cutoff
- activate STCM’s as long as they are hydraulically powered
- increased trim range over over control column switches
How do the FMC’s calculate correct stabilizer trim green band
Use the CG gross weight and takeoff thrust
- if setting outside the midband is required appropriate “nose up” or “nose down” range will also illuminate
How does the aircraft provide a cross check to ensure the correct green band has been selected
Pressure switch on the nose gear oleo
- if there is a discrepancy EICAS advisory STAB GREENBAND will display.
- check correct data entered into FMC
What is the affect of the stabilizer trim if the control wheel stabilizer trim switches are used while the autopilot is enganged?
One autopilot: cause the autopilot to disengage
More than one autopilot: stab trim switch function is inhibited
ALTN stab trim switches affect on Autopilot
- overrides the autopilot trim
- will not cause the autopilot to disengage (one or more)
- cause EICAS - STAB TRIM UNSCHD
How many spoiler panels are provided?
6 on each wing (12 total)
- 5 outboard roll augmentation and operate ailerons
Which spoiler panel does not function as a flight spoiler
The most inboard spoiler panel on each wing (panel 6 and 7)
Which spoiler panels function as speed brakes in flight?
Four inboard spoiler panels on each wing (with speed brakes extended roll and spoilers is combined by spoiler mixer
Which spoiler panel is displayed on the EICAS system display?
Left: indicates fourth panel from the left wing tip (operates as: speed brake ground spoiler and flight spoiler)
Right: position of outer most panel on right wing (ground and flight spoiler)
- speed brakes only indicated by L spoiler position
Which spoiler panels are extended with the speed brake lever in the flight detent position?
- two inboard panels extend to mid travel position
- two middle spoilers extend to their full travel position
When do the spoiler panels extend to the UP position during landing, if the speed brake lever is armed?
- Speed brake lever in arm position
- Thrust levers 1&3 near idle position
- Main gear touch down
- speed brake lever is driven to the UP position extending ALL spoilers
When do the spoilers panels extend to the UP position during landing if the speed brake lever is NOT armed?
Engine 2 or 4 thrust reverser raised to idle detent
- as long as eng 1&3 fwd thrust levers are retarded
- speed brake stows if 1or3 thrust lever is advanced
Since the speed brake is in the DN position during takeoff, what action provides an automatic spoiler function for RTO?
Engine 2 or 4 thrust reverse is raised to idle detent
- as long as engines 1 and 3 fed thrust levers are retarded
- speed brake stows if engine 1 or 3 thrust levers is advanced
For go around protection what action drives the speed brake lever to DN position
If thrust lever 1 or 3 is moved fwd of the retard position
Which elevator panels are displayed on the Surface Position Indicator
Outboard Elevators
Can display flight control synoptic on lower du with STAT on DSP
What can you do if you lose elevator control due to a jam
Shear outs between the inboard and outboard elevators allow the pilot to regain control after a jam with significant manual force.
Describe the elevator feel system
Feed back feel to the pilot according to airspeed
- hyd sys 2&3
- with loss of 2 or 3 ele feel is norm
- with loss of 2&3 ele feel provided by mechanical springs no function of airspeed
How does the aileron lockout system work? Purpose?
Locks out the outboard ailerons at high speeds full travel of outboard ailerons at low speeds
Prevents over controlling
238kts
What would happen if you used aileron trim with the autopilot engaged?
Aileron neutral point is repositioned
- autopilot may (will) compensate
- control wheel will abruptly move to repositioned point when AP disengaged
- prohibited
How do the rudder ratio changers work?
Limit the effect of the rudder pedal displacement at different airspeeds
- even with normal ops excessive cycling inputs can stress rudder
- rudder ratio failure EICAS: RUD RATIO SNGL, RUD RATIO DUAL
- Fails in current limiting condition
• high speed: less travel, reduce x-wind
• low speed: more travel, over stress vert struct
What is the purpose of Yaw Dampers?
- Directional stability
- control Dutch Roll
- provide turn coordination
Note: - receive rates from IRU
- norm both Y/D switches on
- do not result in RUD pedal motion
- sys 2: lower RUD y/d
- sys 3: upper RUD y/d
- if y/d is fault hyd power auto removed from associated and INOP light illuminates
Which spoiler panels function as ground spoilers
All six spoiler panels on each wing extend as ground spoilers
