Term
| How many Flap Control Units (FCUs) are provided? |
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Definition
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Term
| What are the basic functions of the FCUs? |
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Definition
Primary control
Secondary control
Indication and annunciation |
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Term
| Describe the function of the FCUs in secondary mode. |
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Definition
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. |
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Term
| What protection features do FCUs provide for trailing edge flaps in primary mode? |
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Definition
Asymmetry protection
Flap load relief |
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Term
| What protection features do the FCUs provide for trailing edge flaps in secondary mode? |
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Definition
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Term
| Describe each flap group and how each is powered |
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Definition
LEF - pneumatically powered outboard, midspan, and inboard sections
TEF - inboard powered by HYD SYS 1, outboard by HYD SYS 4 |
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Term
| Describe flap extension from 1-5 degrees |
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Definition
0-1 Inboard and midspan leading edge flaps extend
1-5 Outboard leading edge flaps extend and all trailing edge flaps extend to 5 |
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Term
| What happens if a primary control failure occurs in either the inboard or midspan leading edge flap group? Any other group? |
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Definition
Both groups switch to secondary mode
All other flap groups - only the failed group operates in secondary mode |
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Term
| What happens if a failure occurs in a leading edge flap group on only one wing? |
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Definition
Both wings change to secondary mode after a time delay of 20 to 45 seconds
The non-affected side extends before changing modes due to primary mode flap extension rate |
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Term
| When do the flaps return to primary mode after extending in secondary mode? |
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Definition
Trailing edge - once hydraulic pressure is restored or after extension if hydraulic pressure was available
Leading edge - after extension |
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Term
| What happens if a trailing edge asymmetry is detected? |
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Definition
Primary mode is immediately shut down for the asymmetric group
The FCUs do not use secondary mode
Do not use alternate mode |
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Term
| How does the alternate flap mode work? |
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Definition
Bypasses the FCUs
All flaps are extended or retracted by electric motors |
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Term
| Which protections are lost while in alternate mode? |
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Definition
| Load relief and assymetry |
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Term
| What occurs when the Alternate (ALTN) Flaps Arm switch is pushed? |
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Definition
Arms flap alternate control mode
Arms alternate flaps selector
Shuts off primary and secondary modes
Flap lever inoperative |
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Term
| How is flap sequencing different during alternate extension? |
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Definition
All LEF and TEF groups extend immediately
TEF extend to a maximum of 25
During retraction, LEF retract after inboard TEF are completely retracted |
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Term
| How does the flap indicator differ with each mode? |
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Definition
Primary - single tape
Secondary - expanded
Alternate - expanded with tick marks |
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Term
| Describe the flap position indication on EICAS if the standby bus is the only powered AC bus. |
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Definition
Left wing TEF sensors are not powered
Amber X on left outboard and inboard TEF indications
Expanded indication is displayed |
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Term
| What does an amber X mean on an expanded flap display? |
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Definition
| Related flap sensor (and display) inoperative |
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Term
| Describe flap load relief |
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Definition
If airspeed limit is exceeded:
Flaps 30 retracts to 25, and flaps 25 retracts to 20 |
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Term
| What is the affect on the flap system during engine reverse thrust operation? |
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Definition
| Inboard and midspan leading edge flaps retract automatically |
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Term
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Definition
Alternate mode is selected or
All 3 FCUs have failed |
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Term
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Definition
| One or more flap groups are operating in secondary mode |
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Term
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Definition
One of more flap groups have failed to drive in secondary mode or
Asymmetry is detected |
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