Evolution of the A-7A Hydraulic Tubing Permanent Joint System 670585

The use of hydraulic tubing permanent joints, when using the induction brazing method, has proven feasible in the manufacture of aircraft. The use of the permanent-joint method in place of mechanical joints has resulted in a reduction of component weights and a lessening of maintenance problems associated with hydraulic systems. The reasons behind the decision to use permanent joints in the A-7A aircraft and the search for suitable methods and materials is outlined. The testing and application procedures of the permanent-joint system and the results obtained to date are given in detail.
The purpose of this paper is to outline the approach used by LTV Aerospace Corporation for the adoption of hydraulic tubing permanent joints, when using the induction brazing method, for installation on the A-7A Corsair II; the first full-production-model aircraft to incorporate such a system. Background material is presented to trace the course of how the decision was reached to utilize the permanent-joint system; some problems encountered in making the decision; how these problems were resolved through testing and application; and the evolution of the permanent-joint system — from the raw materials used, through the manufacturing process, and the final installation and proven acceptability of the end product.


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