Flight Controls Flashcards
(80 cards)
How many FCUs (flap control units) are provided?
3
What are the basic functions of the FCUs?
- primary mode control
- secondary mode control (through electric motor) - indication and annunciation (flap position information to EICAS and other systems)
- protections
How many groups of leading flaps are provided, names, and how are they normally powered?
3 - inboard, midspan and outboard
pneumatically (bleed air)
What are the two groups of trailing edge flaps, and how are they powered?
inboard, outboard
hydraulically
How are opposite trailing edge flaps connected?
mechanically for symmetry
What protection features do FCUs provide for trailing edge flaps in primary mode?
flap load relief
flap asymmetry
flap disagreement and uncommanded motion protection
What protection features do the FCUs provide for trailing edge flaps in secondary mode?
flap asymmetry
flap disagreement and uncommanded motion protection
(no load relief)
Describe the function of the FCUs in primary mode.
drive LE flaps pneumatically and TE hydraulically to selected position (flap lever)
Describe the function of the FCUs in secondary mode
- If any flap group fails to move to commanded position, FCU switches to secondary mode (elec motors)
- occurs by symmetrical flap group on both wings
What happens if a primary control failure occurs in either the inboard or midspan leading edge flap group?
both groups revert to secondary mode
What happens if a failure occurs in a leading-edge flap group on one wing?
other wing’s flap group will also move to secondary mode. if occurs during flap movement, wing in primary mode will continue to extend flap first
What happens immediately if a trailing edge asymmetry is detected?
primary mode shut down for failed group - FCUs do not use secondary mode
What EICAS Advisory message displays if all three FCUs fail in their control function?
FLAPS CONTROL
How does the Flap Alternate Control mode work?
bypasses FCUs - simplified electric control system/motors
Is there any asymmetry protection in alternate flap mode?
no protections in alternate mode
State the actions that occur when the Alternate (ALTN) Flaps Arm switch is pushed
- arms flap alternate control mode
- arms alternate flaps selector
- shuts off primary and secondary mode operation
- asymmetry protection not available
- flap lever inoperative
What is the maximum extension of the trailing edge flaps in alternate mode?
25
Describe the secondary mode or non-normal expanded flap position indication for leading edge flaps.
Individual flap groups, with position/ drive unit inop shown
Describe the secondary mode or non-normal expanded flap position indication for trailing edge flaps.
individual flap groups, similar to normal, amber if asymmettry or drive failure
What does an amber “X” mean on an expanded flap display?
position sensor for respective flap failed
Describe the Alternate Mode Expanded Flap Position Indicator.
individual LE/TE groups indication, flap positions to 25
Describe the flap position indication on EICAS if the standby bus is the only powered AC bus.
left wing TE sensors not powered, expanded indication with amber x on left TE flaps
What flaps extend when the flap lever is moved from UP to Flaps 1?
inboard and midspan LE
What flaps extend when the flap lever is moved from Flaps 1 to Flaps 5?
outboard LE and TE to flap 5 position