Flap System *** Flashcards
How many Flap Control Units (FCUs) are provided?
• Three
What are the basic functions of the FCUs?
- Primary control
- Secondary control
- Indication and annunciation
How many groups of leading flaps are provided, and how are they normally powered?
- Three groups on each wing: outboard, midspan, and inboard section.
- Normally pneumatically powered from the bleed air duct.
What are the two groups of trailing edge flaps, and how are they powered?
- Inboard and outboard
* Inboard powered by hydraulic system 1 and outboard by system 4
How are opposite trailing edge flaps connected?
• Mechanically, in order to maintain symmetry
What protection features do FCUs provide for trailing edge flaps in primary mode?
- Asymmetry protection
- Flap load relief
- Flap position information to EICAS and other systems
What protection features do the FCUs provide for trailing edge flaps in secondary mode?
- Asymmetry protection
* Flap position information to EICAS and other systems
How do of the FLAPS operate when the FCUs in primary mode.
- LEF are driven pneumatically to the selected position.
* TEF are driven hydraulically to the selected position.
How do of the FLAPS operate when the FCUs in secondary mode.
• If any flap group fails to move to the commanded position, the FCUs
switch to secondary mode for the related group.
• The flap group is driven through electric motors.
What happens if a primary control failure occurs in either the inboard or midspan leading edge flap group?
What EICAS message will be displayed
• Both groups switch to secondary mode
EICAS “Flaps Primary”
What happens if a failure occurs in a leading edge flap group on one Wing?
• The flap groups on both wings change to secondary mode after a short
time delay.
• The non-affected side completes movement before changing to
secondary mode, due to the rapid rate of primary mode flap movement.
What happens immediately if a trailing edge asymmetry is detected?
- Primary mode is immediately shut down for the asymmetric group.
- The FCUs do not use secondary mode
- FLAP DRIVE EICAS Caution Message
What EICAS Advisory message displays if all three FCUs fail in their control function?
• FLAPS CONTROL EICAS Caution message
How does the Flap Alternate Control mode work?
- Bypasses the FCUs
- Can be manually selected
- All flaps are extended or retracted by electric motors
Is there any asymmetry protection in alternate flap mode?
• No
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
- 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
- All flap positions are displayed
- White box outline shows LEF group retracted
- White crosshatch shows LEF group in transit
- Solid green box shows LEF group extended
- Amber Border, Crosshatch, or Solid Box – drive unit inop.
- Indicator motion is continuous between flap detents.
Describe the secondary mode or non-normal expanded flap position indication for trailing edge flaps.
- White – position of inboard and outboard TEF
- Amber – asymmetry or drive failure in related group
- Indicator is continuous between flap detents
What does an amber “X” mean on an expanded flap display?
• Position sensor for respective flap has failed
Describe the Alternate Mode Expanded Flap Position Indicator.
- All flap positions displayed
- Flap position index marks at 5 and 25
- Indicator motion is continuous between flap detents.
Describe the flap position indication on EICAS if the standby bus is the only powered AC bus.
• The left wing TEF sensors are not powered.
• An amber X is displayed on the left outboard and inboard TEF
indications.
• An expanded indication is displayed.
What flaps extend when the flap lever is moved from UP to Flaps 1?
• Inboard and midspan leading edge flap groups.
What flaps extend when the flap lever is moved from Flaps 1 to Flaps 5?
- Outboard leading edge flap groups extend.
* Trailing edge flaps move to Flaps 5 position.
