The leading edges have the fixed leading edges and the leading edge slats. The leading edges are installed on the front spars and have some components of the slat actuating and anti-ice systems.

The fixed leading edge is made from skin panels and ribs. The leading edge ribs make the assembly stronger. The skin panels and shrouds are made of clad aluminum sheet. Some components of the anti-ice and slat systems are installed in the fixed leading edge.

The leading-edge slats are used with the flaps to increase lift. The slats are extended to 20 degrees when the flaps are set to the takeoff and landing positions. The leading edge slat of each wing is divided into four sections. The four slat sections are installed forward of the front spar from WS129.00 to WS537.00. The slat sections are extended by the linear actuator system operated from the central power drive unit. Each slat section has two actuators and two support tracks. Each slat is held by rails that move on rollers installed on support fittings in the leading edge.

During extension of the leading-edge slat, the leading-edge aerodynamic seals prevent airflow through the cutouts in the fixed leading-edge skin. These cutouts are used for attachment, actuation, and heating of the leading edge slats.

The slat sections are made from the structures that follow:

• Ribs
• Longitudinal spar
• Trailing edge wedge
• Skin

Ribs are installed at each support track. The slat tracks are made of high strength steel.

The slat control system on each wing is made from the components that follow:

• Eight actuators and fittings
• Fourteen torque shafts
• One tip brake
• One position feedback transducer
• Four bearing supports

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The fixed leading edge assembly is made from the inboard and the outboard leading edges. The inboard fixed leading edge is found between WS47.61 and WS129.00. It has no slats and is the wing leading edge. The outboard fixed leading edge is found between WS129.00 to WS544.00. It has slats and is the rear side structure of the leading edge slats.

Wing Landing/Taxi Light Lenses

There are two wing landing/taxi light lenses. The lenses are made from transparent material. They are installed in a recess of the wing structure and are flush with the fixed leading edge. These lenses protect the wing landing/taxi lights from dirt and foreign object damages.

Fixed Leading Edge P-Seals

The fixed leading edge p-seals are installed on the outer side of the fixed leading edge at WS129.00. The p-seals fill the clearance between the inner side of the No.1 slat and the outer side of the fixed leading edge (when the slats are retracted). The p-seals also help the aerodynamic airflow of the wing.

Leading Edge Lower Access-Panels

There are fifteen access panels on the lower side of each leading edge. The access panels give access for the adjustment of the flight controls, the replacement of components, and the inspection of components. The access panels are made from clad aluminum.

The fixed leading edge is made from the structures that follow:

Slat Track Rollers

Slat track rollers are installed between each rib between the slat trackrails. The slat track rollers are the supports which hold the slat trackrails. These are two types of slat track rollers: side rollers and main rollers. The side rollers are installed on the two inner sides of the rib. The main rollers are installed between each rib.

Leading Edge Panels

The leading edge panels of the leading edge are usually made of sheet metal. Leading edge panels are installed on the front of each front spar of the wings.

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The leading edge slats are used with the trailing edge flaps to give more lift during take-off. When the leading edge slats fully extend, they give more surface to the wing to let the aircraft operate from short runways.

The leading edge slats structure has space for the components that follow:

• Slat Actuators
• Telescopic Duct (No. 1 slat)
• Piccolo Ducts

The leading edge slats are installed forward of the front spar from WS129.00 to the winglet. There are four leading edge slats on each wing. The slats are identified as the No.1 through the No.4 slat from the inner side to the outer side of the leading edge. Each leading edge slat has the structures that follow:

Slat Track Rail and Attachment

Each slat is held by rails that move on rollers installed on support fittings in the leading edge.

Each track rail is attached to a rib fitting of the slat. A bushing is used to control track rail movement in the joint between the track and the support fitting. Track rail stops are installed on all tracks to prevent too much travel of the slat during retraction.

Slat Spigot Pin and Attachment

A spigot pin is installed in the center location on the No. 2 slat, No. 3 slat and No. 4 slat. The spigot pin decreases the slat distortion in the retract position. Each spigot pin is installed on the rib fitting of the slat.

Slat Interconnect Pin and Fitting

A pin is installed to connect the slats between the No. 1 and No. 2 slats, between the No. 2 and No. 3 slats, and between the No. 3 and No. 4 slats.

Clearance is given between the interconnect pin and the fitting. The interconnect pin does not let the slat disconnect after damage.

Slat Structural Assembly

The slat structural assemblies has four sections that you can remove independently. Each slat section is made from a contour skin panel, machined ribs, general ribs, spar, and back panel. The skin panel, the general ribs, the spar, and the back panel are made from sheet metal. The machined rib fittings are used for the attachment of the actuators, tracks, spigot pins, and interconnect pins.

Routing is supplied for the piccolo ducts of the wing anti-icing system through structural components in each slat assembly.

The back panels give access to anti-icing system components installed in the slat assemblies.

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