FLAP SYSTEM

Question 1

How many Flap Control Units (FCUs) are provided?

Answer 1

• Three

FCOM, VOL 2; 9.20.13

Question 2

What are the basic functions of the FCUs?

Answer 2

• Primary control
• Secondary control
• Indication and annunciationFCOM, VOL 2; 9.20.13

Question 3

How many groups of leading flaps are provided, and how are they normally powered?

Answer 3

• Three groups on each wing: outboard, midspan, and inboard section.
• Normally pneumatically powered from the bleed air duct of your respective side.FCOM, VOL 2; 9.20.13

Question 4

What are the two groups of trailing edge flaps, and how are they powered?

Answer 4

• Inboard and outboard
• Inboard powered by hydraulic system 1 and outboard by
system 4

FCOM, VOL 2; 9.20.13

Question 5

How are opposite trailing edge flaps connected?

Answer 5

• Mechanically, in order to maintain symmetry.

FCOM, VOL 2; 9.20.13

Question 6

What protection features do FCUs provide for trailing edge flaps in primary mode?

Answer 6

• Asymmetry protection,
• Disagree and uncommanded motion,
• Flap load relief for flaps 25 and 30, and
• Flap position information to EICAS and other systemsFCOM, VOL 2; 9.20.13

Question 7

What protection features do the FCUs provide for trailing edge flaps in secondary mode?

Answer 7

• Asymmetry protection,
• Disagree and uncommanded motion,
• Flap position information to EICAS and other systems.FCOM, VOL 2; 9.20.13

Question 8

Describe the function of the FCUs in primary mode?

Answer 8

• LEF are driven pneumatically to the selected position.
• TEF are driven hydraulically to the selected position.FCOM, VOL 2; 9.20.13

Question 9

Describe the function of the FCUs in secondary mode?

Answer 9

• 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.
- the change is for symmetrical flap groups on both wings.

FCOM, VOL 2; 9.20.14

Question 10

What happens if a primary control failure occurs in either the inboard or midspan leading edge flap group?

Answer 10

• Both groups switch to secondary mode.

FCOM, VOL 2; 9.20.14

Question 11

What happens if a failure occurs in a leading edge flap group on one Wing?

Answer 11

• The flap groups on both wings change to secondary mode after a time delay.
• The non-affected side completes movement before changing to secondary
mode, due to the rapid rate of primary mode flap movement.

FCOM, VOL 2; 9.20.14

Question 12

What happens immediately if a trailing edge asymmetry is detected?

Answer 12

• Primary mode is immediately shut down for the
asymmetric group.
• The FCUs do not use secondary mode
• FLAP CONTROL EICAS Caution Message If all three FCU’s fail.

FCOM, VOL 2; 9.20.13

Question 13

What EICAS Advisory message displays if all three FCUs fail in their control function?

Answer 13

• FLAPS CONTROL EICAS Caution message.

FCOM, VOL 2; 9.20.13/ 9.30.1

Question 14

How does the Flap Alternate Control mode work?

Answer 14

• Bypasses the FCU’s, so no protection is provided.
• Is manually selected
• All flaps are extended or retracted by electric motors.
• Flap selector is inoperative.
• After arming the alternate mode, extension and retraction is
accomplished with the Alternate flaps selector.

FCOM, VOL 2; 9.20.14

Question 15

Is there any asymmetry protection in alternate flap mode?

Answer 15

• No

FCOM, VOL 2; 9.20.14

Question 16

State the actions that occur when the Alternate (ALTN) Flaps Arm switch is pushed?

Answer 16

• Arms flap alternate control mode
• Arms alternate flaps selector
• Shuts off primary and secondary mode operation,
• Asymmetry protection is not available.
• Flap lever inoperative.FCOM, VOL 2; 9.10.8

Question 17

What is the maximum extension of the trailing edge flaps in alternate mode?

Answer 17

• 25

FCOM, VOL 2; 9.10.8

Question 18

Describe the secondary mode or non-normal expanded flap position indication for leading edge flaps?

Answer 18

• 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 boarder - Drive unit inoperative with flap group retracted.
• Amber solid box – Drive unit inoperative with flap group extended.
• Amber cross hatch- Drive unit inoperative with flap group partially extended.FCOM, VOL 2; 9.10.11

Question 19

Describe the secondary mode or non-normal expanded flap position Indication for trailing edge flaps?

Answer 19

• White – position of inboard and outboard TEF
• Amber – asymmetry or drive failure in related groupFCOM, VOL 2; 9.10.11

Question 20

What does an amber “X” mean on an expanded flap display?

Answer 20

• Position sensor for respective flap has failed.

FCOM, VOL 2; 9.10.11

Question 21

Describe the Alternate Mode Expanded Flap Position Indicator?

Answer 21

• All flap positions displayed
• Flap position index marks at 5 and 25
• Indicator motion is continuous between flap detents.FCOM, VOL 2; 9.10.12

Question 22

Describe the flap position indication on EICAS if the standby bus is the only powered AC bus?

Answer 22

• 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.

FCOM VOL 2 9.20.15

Question 23

What flaps extend when the flap lever is moved from UP to Flaps 1?

Answer 23

• Inboard and midspan leading edge flap groups.

FCOM, VOL 2; 9.20.14

Question 24

What flaps extend when the flap lever is moved from Flaps 1 to Flaps 5?

Answer 24

• Trailing edge flaps move to Flaps 5 position.
• Outboard leading edge flap groups extend.

FCOM, VOL 2; 9.20.15

Question 25

What flap sequencing occurs when using alternate flaps?

Answer 25

• During extension, all LEF and TEF groups extend immediately. • TEF extend to a maximum of 25. • During retraction, all LEF groups retract after inboard TEF are completely retracted. FCOM, VOL 2; 9.20.15

Question 26

Describe flap load relief?

Answer 26

• Protect s the flaps from excessive air loads if airspeed limits are exceeded with flaps 25 or 30 selected. • If airspeed limit is exceeded , the flaps will retract to 25 or 20 to eliminate the exceedance. • Flaps extend once airspeed is sufficiently reduced. - Flap load relief is not available in secondary or alternate mode. FCOM, VOL 2; 9.20.13

Question 27

How long does the flap indication on primary EICAS remain displayed after all flaps are up?

Answer 27

• 10 seconds FCOM, VOL 2; 9.20.15

Question 28

What is the affect on the flap system during engine reverse thrust operation?

Answer 28

• Inboard and midspan leading edge flaps retract automatically - Flap position indicator changes to reflect flaps in transit. FCOM, VOL 2; 9.20.15