Leading edge slats and trailing edge flaps provide the ability to alter the overall shape of the wing.The purpose of the leading edge slat-system is to increase the lift of the wing at slow speeds. The leading edge slat-system has eight high-lift slat panels, four on each wing. The four slat panels on each wing are controlled by eight slat actuators. Each slat panel is controlled by two slat actuators. The The slat panels extend and retract with the flaps to increase the lift of the aircraft during take-off and landing, yet still be efficient at high cruise speeds. The eight leading edge slats deploy perpendicular to the leading edge while the six fowler flap panels deploy streamwise. Control is through a single cockpit selector handle. The systems are completely electrical with separate power drive units for each.

The eight leading edge slats and six trailing flaps are controlled by the two SFCUs and respond to inputs from the slat/flap selector handle in the cockpit. The slats have only two positions, IN or OUT (20 degrees) while the flaps have four positions, 0 degree, 6 degrees, 16 degrees, and 30 degrees. Slat/flap position is detected by a resolver on the outboard end of the drive system on each side. The systems operate sequentially, without overlap. The slats will extend completely and then the flaps will extend to the selected position. Upon retraction, the flaps will completely retract first and then the slats. After receiving input from the cockpit selector handle, the SFCUs sends signals to release the power drive unit brakes and the asymmetry brake units. Power is then applied to the motors, the drive shafts rotate driving the actuators and the surfaces move to the selected position. The position as sensed by the resolvers is sent to the SFCUs. When they reach the selected position, power is removed from the motors and the brakes and the surfaces are held in position. Any difference in travel between the two sides would be detected by the SFCUs, which would stop the system at that point and inhibit further travel. The cockpit crew would be informed of the failure.

The slat actuators change the input movement from the torque tubes into linear output movement. These rigid torque tubes, installed between the slat actuators and the support bearings, make sure that all the slat actuators are synchronized. Two asymmetry brakes near each wingtip make sure the torque tubes hold their position. The asymmetry brakes are engaged and released electrically. Each asymmetry brake has two solenoids and can be released by each of the slat/flap control units (SFCU). The position of the torque tubes is measured by a slat resolver installed on the slat actuators in each wingtip. The torque tubes are turned by a power drive unit (PDU) which supplies power to the two sides at the same time through the angle gearboxes.

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There are two models of torque tubes: female/female and female/male. They are cylinders of different lengths and are installed in the leading edge of the inboard, middle, and outboard wing sections.

The torque tubes transmit the movement from the PDU to the actuators. The actuators are connected directly to the mobile structure of the surfaces through the angle gearboxes and support bearings. The torque tubes have universal joints to absorb incorrect system alignment. They also have a pin at one end to prevent axial movement.

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The angle gearboxes are solid cylinders with a male shaft on each side. The male shafts go into the female part of the torque tube. They are installed in the lower middle fuselage. The angle gearboxes transmit torque and turn movement to the slat torque tubes. They have drilled shafts for the attachment of the torque tubes.

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There are 16 slat system actuators, eight on each wing. The slat system actuators are installed in the leading edges of the inboard, middle, and outboard wing sections. The slat system actuators are the linear ballscrew type with ballscrew shafts.

The slat system actuators have a fixed end with a bearing and a movable end. The fixed end with a bearing attaches to the aircraft structure. The movable end attaches to the slats to extend and retract the slats. The slat system actuators are controlled from the PDUs through the torque tubes. The actuators transmit force to the spars on the leading edge of the wings.

The slat system actuators are connected directly to the mobile structure of the surfaces. They have a force limiter device which makes sure that torque is not sent back through the torque tubes if the surfaces are caught or damaged.

There are eight balls screw slat actuators on each wing, two per slat panel. A total of nine different assemblies are used. The actuators are No. 1 through 8 from the inboard to outboard wing. No. 1 through 7 are paired left and right, the No. 8 actuators on each side are different, they have mirror image installations. The No. 1 actuator on each side is the master actuator for installation/rigging reference. It provides the primary overtravel stops for the system. The overtravel stops on the remaining actuators should never make contact.

Resolvers, used for position sensing, are mounted on the outboard actuator on each side. The actuators include force limiters to protect the aircraft structures from PDU torque damage because of a roller or track jam. These force limiters are self-resetting when the direction of rotation is reversed.

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A series of 26 driveshafts are used to transmit rotary power from the PDU to all Slat actuators. The tubes are constructed of anodized aluminum alloy. Permanently lubricated universal joints allow up to a 5 degrees axial misalignment. Telescopic splined shafts, axially coupled by trubolts, facilitate shaft removal/installation. One end of the shaft is free-floating. Inspection holes are provided to manually confirm spline engagement.

35 degrees Slat angle gearboxes are installed in the driveline between the PDU and each No. 1 Slat actuator. Three bearing support assemblies on each wing provide support for torque shafts where shaft lengths are limited for critical speed or maintainability. One is located between the angle gearbox and No. 1 actuator, one is between No. 3 and 4, and one is between No. 5 and 6 actuators.

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Four panels per wing, shaped to conform to the leading edge, are installed on the leading edge. Two actuators position each panel. Tracks mounted on the panels ride on roller/guides within the wing leading edge. Each panel contains ducting and sensors for wing anti-icing. A series of access panels are installed on the lower wing surface to allow access to the Slat drive components. The slat panels includes the following:

• No. 1 Slat Panels
• No. 2 Slat Panels
• No. 3 Slat Panels
• No. 4 Slat Panels

No. 1 Slat Panels

The No. 1 slat panels are aluminum skin ribs with thermal anti-icing installed in the forward spar. The No. 1 slat panels are the leading edge of the inboard wing sections to give them an aerodynamic shape.

The No. 1 slat panels are made from the structures that follow:

• Slat Track and Attachment
• Slat Spigot Pin and Attachment
• Slat Interconnect Pin and Fitting
• Slat Structural Assembly

The No. 1 slat panels include the components in the slat control system and the anti-icing systems that follow:

• Slat System Actuators
• Telescopic Duct
• Piccolo Tubes
• Telescopic Wiring

The No. 1 slat panels are held by tracks that move on the rollers installed in the fixed leading edge. Each No. 1 slat panel has three tracks. Each track is attached to the machined rib fitting of the slat. In the joint between the track and the slat, an eccentric bushing is used to let the track location adjust. Stops are installed on all tracks to prevent slat overtravel during retraction.

No. 2 Slat Panels

The No. 2 slat panels are aluminum skin ribs with thermal anti-icing installed in the forward spar. They are the leading edge of the inner-middle wing sections to give them an aerodynamic shape.

The No. 2 slat panels are made from the structures that follow:

• Slat Track and Attachment
• Slat Spigot Pin and Attachment
• Slat Interconnect Pin and Fitting
• Slat Structural Assembly

The No. 2 slat panels include the slat control system and the anti-icing systems that follow:

• Slat System Actuators
• Telescopic Duct
• Piccolo Tubes
• Telescopic Wiring

The No. 2 slat panels are held by tracks that move on the rollers installed in the fixed leading edge. Each No. 2 slat panel has two tracks. Each track is attached to the machined rib fitting of the slat. In the joint between the track and the slat, an eccentric bushing is used to let the track location adjust. Stops are supplied on all tracks to prevent slat overtravel during retraction.

No. 3 & No. 4 Slat Panels

The No. 3 and No. 4 slat panels have the same description as the No. 2 slat panels, except for the differences that follow:

• No. 3 slat panels are the leading edge of the outer-middle wing section
• No. 4 slat panels are the leading edge of the outboard wing section

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The slat PDU is installed in the mid-lower fuselage. The PDU is a 270 VDC brushless-motor device. It includes two motors which can be removed. It has a circular body with shafts on the two faces which transmit torque and turn-movement.

There is a friction-type brake between each motor and the differential gearset. This brake is engaged by a spring and released by a solenoid.

There is a slip clutch between the gearset and the output. The slip clutch prevents damage to the gearbox and the motor if the branch torque limiter is in operation. There is one branch torque limiter at the output of the PDU for each wing of actuator torque tubes.

The PDU is controlled by the SFCUs and has the functions that follow:

• Change electrical input into torque and turn-movement outputs to move the slats
• Supply system brake and position hold for usual operation
• Limit the torque to prevent damage to the system and aircraft in malfunction-mode conditions
• Supply a slip clutch function to prevent damage to the gearbox and motor in malfunction-mode conditions

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The slat PDU motors are installed in the lower middle fuselage. The PDU motors move the slat actuators by the torque tubes. Each PDU motor has two electrical connectors for the motor windings. Two other connectors are for the thermal switch, brakes, motor field, and motor field director.

In normal operation, the output of the PDU is the sum of the speed of the two motors. If a single-channel malfunction occurs (malfunction of a motor, PDU brakes, SFCU, or other), the defective motor and brake supply a mechanical ground path. The PDU operation is decreased to half speed with the use of a single motor.

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There are six support bearings, three on each wing. The support bearings are installed in the leading edge of the inboard, middle, and outboard wing sections. The support bearings are the plain type. Each support bearing has a cylindrical shape and a plate with three holes. The holes are used to attach the support bearing to the aircraft structure and to make the mechanism more rigid.

A shaft goes through the support bearings to connect them to the torque tubes. The support bearings transmit torque and turn-movement in the torque tubes.

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The slat resolver is installed on the outboard slat actuator of each wing.

The slat resolver is a dual-channel resolver. It includes a housing and one electrical connector. It transmits an analog position signal to the SFCUs in relation to the angular movement of the torque tubes (surface position).

The slat resolvers have a cylindrical shape and a triangular plate with holes in the corners. The holes are used to attach the slat resolvers to the outboard slat actuator. They have a smooth shaft with a hole for a pin and transmit a change-of-state signal when turned.

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The slat asymmetry brakes are cylinders with an electrical connector and a shaft on the two faces. The shafts transmit movement to the torque tubes. The asymmetry brakes are installed on the leading edge of the wings near the outboard flaps.

The slat asymmetry brakes are engaged by springs. They are released by a signal from the solenoid in the SFCU when a movement input signal is received. There are two solenoids in each slat asymmetry brake. Each solenoid is controlled by one of the SFCUs and each SFCU can release the brake. The asymmetry brakes are the mechanical-interference type and are engaged only when the system is static.

The asymmetry brakes have the functions that follow:

• Protection against asymmetry in malfunction-mode conditions
• Position hold if a PDU brake malfunction occurs
• Transmission of the torque and turn-movement

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The slat links attach the slat track rails to the slat panels. The load of the slat panel is transmitted to the track rails as the slats are extended and retracted.

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The slat track rails connect the slat panels to the attachment fittings on the leading edge spars of the wings. The rails move over rollers in the fittings when the slat system actuators retract or extend. Bolts attach the slat links to the slat track rails. They are attached to the slat panel by bolts that have bushings.

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Component Location Index
IDENT	DESCRIPTION	LOCATION	IPC REF
-	SLAT-SYSTEM TORQUE TUBES	ZONE(S) 163/164 ZONE(S) 511/611 ZONE(S) 512/612 ZONE(S) 513/613 ZONE(S) 514/614	27-53-01 [ GX ] [ GXRS ] [ G5000 ]
-	SLAT-SYSTEM ANGLE GEARBOXES	ZONE(S) 163/164	27-53-05 [ GX ] [ GXRS ] [ G5000 ]
-	SLAT SYSTEM ACTUATORS	ZONE(S) 511/611 ZONE(S) 512/612 ZONE(S) 513/613 ZONE(S) 514/614	27-53-09 [ GX ] [ GXRS ] [ G5000 ]
-	SLAT-SYSTEM SUPPORT BEARINGS	ZONE(S) 520/620 ZONE(S) 512/612 ZONE(S) 513/613	27-53-13 [ GX ] [ GXRS ] [ G5000 ]
B13/B14	SLAT POWER-DRIVE UNIT (PDU)	ZONE(S) 167/168	27-53-33 [ GX ] [ GXRS ] [ G5000 ]
B13/B14	SLAT POWER-DRIVE UNIT (PDU) MOTORS	ZONE(S) 167/168	27-53-37 [ GX ] [ GXRS ] [ G5000 ]
MT77/MT78	SLAT RESOLVERS	ZONE(S) 514/614	27-53-41 [ GX ] [ GXRS ] [ G5000 ]
A130/A131	SLAT ASYMMETRY BRAKES	ZONE(S) 514/614	27-53-45 [ GX ] [ GXRS ] [ G5000 ]
-	SLAT LINKS	ZONE(S) 511/611 ZONE(S) 512/612 ZONE(S) 513/613 ZONE(S) 514/614	27-53-49 [ GX ] [ GXRS ] [ G5000 ]
-	SLAT TRACK RAILS	ZONE(S) 511/611 ZONE(S) 512/612 ZONE(S) 513/613 ZONE(S) 514/614	27-53-53 [ GX ] [ GXRS ] [ G5000 ]

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