| Flap Alternate Extension In the event that Hydraulic System B fails, an altemate method
of extending the LE devices and extending and retracting the TE flaps is provided.
The TE flaps can be operated electrically through the use of two Alternate Flap Switches. The guarded ALTERNATE FLAPS Master Switch closes a flap bypass valve to prevent hydraulic lock of the flap drive unit and arms the Alternate Flaps Position Switch. The ALTERNATE FLAPS Position Switch controls an electric motor that extends or retracts the TE flaps. The switch must be held in the DOWN position until the flaps reach the desired position. No asymmetry or skew protection is provided through the Alternate (electrical) Flap Drive System. When using altemate flap extension the LE flaps and slats are driven to the full extended position using power from the Standby Hydraulic System. In this case the ALTERNATE FLAPS Master Switch energizes the standby pump and the ALTERNATE FLAPS Position Switch, held in the down position momentarily, fully extends the LE devices. NOTE The LE devices cannot be retracted by the Standby Hydraulic System. |