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Flap / Slat system
The slat system consists of 8 slats surfaces on the leading edge of the wing (4 per wing) and 4 double slotted flap surfaces on the trailing edge of the wing (2 per wing)
Slat-Flap control lever commands the SF-ACE. Deployment is then commanded by 2 x SF-ACE and electrically operated by 2 x PDU's (Slat PDU and Flap PDU)
Movement is sequenced such that slats extend first and flaps retracts first.
Skew Protection
Electronic skew sensors monitor differential movement between neighbouring panels of Flap(Slat). If exceeds acceptable limits, the SF-ACE's shut down generating FLAP(SLAT) FAIL
Strike Protection
If SF-ACE detects excessive load through PDU, electrical power removed from respective PDU to prevent further movement in the selected direction, generating FLAP(SLAT) FAIL
In such cases, the affected surface can be commanded in the opposite direction
If after 3 unsuccessful attempts to select a position, the strike protection cuts the PDU power for both directions
Slat/Flap system interlocks
If the RAT is the only source of electric power, the flap and slats operate at half speed.
The SF-ACE prevents deployment position 3 to assure adequate airspeed for the RAT
Slat/Flap control lever
Lever positon | Slat position | Flap Position | Detent/Gated |
0 | 0 | 0 | Detent/Stop |
1 | 15 Deg | 5 Deg (E170) 7 Deg (E190) | Detent |
2 | 15 Deg | 10 Deg | Detent |
3 | 15 Deg | 20 Deg | Detent |
4 | 15 Deg | 20 Deg | Gated/Stop |
5 | 25 Deg | 20 Deg | Detent |
FULL | 25 Deg | 35 Deg (E170) 37 Deg (E190) | Detent/Stop |
EICAS Messages
FLAP(SLAT) FAIL
SLAT-FLAP LEVER DISAG
See also
Secondary Flight Control System