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 secondary 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