Flap System Flashcards
How many Flap Control Units (FCUs) are provided?
• Three
Note:FCOM, VOL 2; 9.20.14
What are the basic functions of the FCUs?
- Primary control
- Secondary control
- Indication and annunciation
Note:FCOM, VOL 2; 9.20.14
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.
Note:FCOM, VOL 2; 9.20.13
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
Note:FCOM, VOL 2; 9.20.14
How are opposite trailing edge flaps connected?
• Mechanically, in order to maintain symmetry
Note:FCOM, VOL 2; 9.20.14
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
Note:FCOM, VOL 2; 9.20.14
What protection features do the FCUs provide for trailing edge flaps in secondary mode?
- Asymmetry protection
- Flap position information to EICAS and other systems
Note:FCOM, VOL 2; 9.20.14
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.
Note:FCOM, VOL 2; 9.20.14
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.
Note:FCOM, VOL 2; 9.20.14
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”
Note:FCOM, VOL 2; 9.20.14
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.
Note:FCOM, VOL 2; 9.20.15
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
Note:FCOM, VOL 2; 9.20.15, 9.30.1
What EICAS Advisory message displays if all three FCUs fail in their control function?
• FLAPS CONTROL EICAS Caution message
Note:FCOM, VOL 2; 9.20.14
How does the Flap Alternate Control mode work?
- Bypasses the FCUs
- Can be manually selected
- All flaps are extended or retracted by electric motors
Note:FCOM, VOL 2; 9.20.15
Is there any asymmetry protection in alternate flap mode?
• No
Note:FCOM, VOL 2; 9.20.15