A method is described for the testing of aircraft friction units in order to determine fields of applications of different combinations of structural materials and lubricants. The results of the tests for the load-carrying capacity and efficiency of structural materials and lubricants for aircraft friction units allow to draw the following conclusions. (1) The load-carrying capacity of bronzes in friction is governed by interaction between lubricants and surface layers of structural materials (coatings) and differs up to 2.7 times depending on the lubricant. (2) The load-carrying capacity of bronzes in static loading differs up to 1.7 times depending on the lubricant. (3) The friction coefficient changes in time and depends on antifriction properties of structural materials and lubricants, the severity of transformations in the surface layer and the lubricant. (4) The running-in of the working surfaces increases the load-carrying capacity of high-strength bronzes in sliding by up to 75%. (5) The application of duplicating and backup lubricants should be substantiated based on results of comparative tests to provide the equivalent load-carrying capacity and efficiency. The presented results are just a modest contribution to the necessary body of tests. Since they are labor consuming and costly the developers and testers of aircraft friction units, lubricants, and coatings should join their efforts. Tests involving the proposed method will gradually help accumulate the database of combinations of structural materials and lubricants for aircraft friction units, determine the sphere of their application, specify justifiably loading conditions in designing, schedule maintenance, predict the time of repair and set the full unit life. The experience that the Sukhoi Design Bureau has gained raises the question of the development of regulations for standardizing tests, correcting the Aviation Rules regarding the application of materials and lubricants in heavy-duty friction units of aircrafts, thus promoting their reliability, life, safety, and failure-free performance of their functions. (to be continued)