DOC AIRBUS | AMM A320FCENTER WING - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
1. General
The center wing box (section 21) is installed in the fuselage between the frames FR36 and FR42.
It provides the cantilever attachment for the wings, distributes their load in the fuselage and can form an optional integral fuel tank.
The wings of the aircraft are attached to the box by the left and right RIB1.
Access for maintenance to the center wing box is through two triangular openings in the rear spar secured to frame FR42.
The lower skin panel of the center wing box is fitted out to house the fuel tank pumps.
The center wing box (section 21) is installed in the fuselage between the frames FR36 and FR42.
It provides the cantilever attachment for the wings, distributes their load in the fuselage and can form an optional integral fuel tank.
The wings of the aircraft are attached to the box by the left and right RIB1.
Access for maintenance to the center wing box is through one triangular opening in the rear spar secured to frame FR42.
The lower skin panel of the center wing box is fitted out to house the fuel tank pumps.
** ON A/C NOT FOR ALL The center wing box (section 21) is installed in the fuselage between the frames FR36 and FR42.
Center Wing BoxIt provides the cantilever attachment for the wings, distributes their load in the fuselage and can form an optional integral fuel tank.
The wings of the aircraft are attached to the box by the left and right RIB1.
Access for maintenance to the center wing box is through two triangular openings in the rear spar secured to frame FR42.
The lower skin panel of the center wing box is fitted out to house the fuel tank pumps.
The center wing box (section 21) is installed in the fuselage between the frames FR36 and FR42.
It provides the cantilever attachment for the wings, distributes their load in the fuselage and can form an optional integral fuel tank.
The wings of the aircraft are attached to the box by the left and right RIB1.
Access for maintenance to the center wing box is through one triangular opening in the rear spar secured to frame FR42.
The lower skin panel of the center wing box is fitted out to house the fuel tank pumps.
2. Description
The main structure comprises:
The main structure comprises:
- two forward and rear spars
- two frames FR36 and FR42
- an upper skin panel
- a lower skin panel
- six rod assemblies
- two ribs RIB1 left and right
- ten frame support assemblies (left and right).
A. Spars
(1) The front spar consists of a core made up of six vertical stiffeners on the outer face, four horizontal stiffeners on the inner face, an angle section which connects the spar to the upper skin panel and a flexible formed section which provides a seal between the center wing box and the pressure bulkhead.
(2) The rear spar comprises a core machined from a drop forging.
B. Frames FR36 and FR42
Frames FR36 and FR42 integrate the center wing box in the fuselage.
Each frame comprises two forward and two rear attach-fittings assembled back-to-back and riveted together.
A splice replaces the left and right attach-fittings in the top section of the frame.
The lower ends of the frame are secured to the center wing box by bolts.
Frames FR36 and FR42 integrate the center wing box in the fuselage.
Each frame comprises two forward and two rear attach-fittings assembled back-to-back and riveted together.
A splice replaces the left and right attach-fittings in the top section of the frame.
The lower ends of the frame are secured to the center wing box by bolts.
C. Upper and Lower Skin Panels
(1) Upper skin panel
The inner face of the upper skin panel is strengthened by seventeen transverse stiffeners. Six longitudinal beams are secured to the outer face ; they stiffen the wing center box and support the cabin floor.
The inner face of the upper skin panel is strengthened by seventeen transverse stiffeners. Six longitudinal beams are secured to the outer face ; they stiffen the wing center box and support the cabin floor.
(2) Lower skin panel
The lower skin panel consists of three panels:
The lower skin panel consists of three panels:
- a forward panel
- a center panel
- a rear panel.
- thirteen T stiffeners including two joint fittings:
joint fitting STGR8 provides the joint between the forward panel (STGR1 to STGR8) and the center panel (STGR8 to STGR11).
joint fitting STGR11 provides the joint between the center panel and the rear panel (STGR11 to STGR15). - an inner pump bracket fitted with two outer pump brackets and blank fittings for the fuel pump
- a forward angle section which provides the joint between the front spar and the lower skin panel.
D. Rod Assembly
Inside the wing box, the lower skin and upper skin panels are connected by an assembly of rods which stiffen the center wing box.
This assembly of rods comprises four assemblies of six rods and two assemblies of seven rods.
The two seven-rod assemblies are located in the vertical plane formed by the two center beams of the upper skin panel, on either side of the aircraft centerline.
The four six-rod assemblies are located in the vertical planes formed by the two left and right lateral beams.
Inside the wing box, the lower skin and upper skin panels are connected by an assembly of rods which stiffen the center wing box.
This assembly of rods comprises four assemblies of six rods and two assemblies of seven rods.
The two seven-rod assemblies are located in the vertical plane formed by the two center beams of the upper skin panel, on either side of the aircraft centerline.
The four six-rod assemblies are located in the vertical planes formed by the two left and right lateral beams.
E. Ribs
The center wing box is closed by the left RIB1 and the right RIB1.
These two ribs consist of: a forward vertical T-fitting, a rear vertical T-fitting, a lower skin T-fitting, an upper skin cruciform fitting, three vertical stiffeners and a door.
The lower skin T-fitting and the upper skin cruciform fitting provide the joint for the outer wing, the panel and the RIB1.
An outer splice strengthens the joint between the lower skin panel, the RIB1 and the wing.
The center wing box is closed by the left RIB1 and the right RIB1.
These two ribs consist of: a forward vertical T-fitting, a rear vertical T-fitting, a lower skin T-fitting, an upper skin cruciform fitting, three vertical stiffeners and a door.
The lower skin T-fitting and the upper skin cruciform fitting provide the joint for the outer wing, the panel and the RIB1.
An outer splice strengthens the joint between the lower skin panel, the RIB1 and the wing.
F. Supports of Frames FR37 to FR41
Frames FR37 to FR41 are part of the fuselage and are supported on frame lower sections (The left and right frame lower sections).
The frame lower section comprises two parts:
Frames FR37 to FR41 are part of the fuselage and are supported on frame lower sections (The left and right frame lower sections).
The frame lower section comprises two parts:
- an outer frame lower section attached to the upper skin panel and the upper skin cruciform fitting of RIB1.
- an inner frame lower section attached to RIB1 inside the center wing box and to the lower skin T-fitting which connects RIB1 to the lower skin panel.