Master process sheets for fabrication of CFC centre fuselage parts for TEJAS (Light Combat Aircraft)

Under Carnage Doors are doubly curved co-cured construction consists of skin, bladed stiffener and back to back channels. In addition, this is the only composite part that experiences the maximum load during take-off and landing. This has opened a greater challenge for realising the airworthy components. Because of its complex shape and due to the inherent properties of composite, achieving the contour has become a subject of challenge. The systematic approach that ACD has followed ended with an innovative idea of opened NMG to accommodate the spring-in phenomena. The stiffeners and channels are co-cured and co-bonded to the basic skin. To exploit the technical advantages of composite. The essence of co-curing technology depends on tooling. The long experience of ACD in tooling enable to use split tools, in between stiffener and solid cores for channels. The mixing ratio of resin and aluminium powder is selected precisely, so that co-efficient of thermal expansion (CTE) is sufficient enough to provide the required pressure to consolidate the laminate. A wise decision has been by ACD to co-cure the cover plate assemblies to avoid the mismatches. A novel technology is adopted for positioning the stiffeners precisely and to maintain dimensional accuracy between the hinge locations and upplog positions. The sub-tools are made using derivative tooling technique to avoid any mismatch between tool and component. Realisation of sandwich doors that involved machining of honey comb core is well *established at ACD using special cutters and core holding devices. This report explains the manufacturing process in a systematic manner to realise the airworthy components