The book discusses the planning, preparation, conduct and analysis of flight test results for liquid-propellant rocket engines. The method of justifying the volume of measurements during flight tests required to establish the technical condition of the engine, clarify the causes of malfunctions and assess the sufficiency of simulating flight conditions during bench testing of LRE. Provides basic information about telemetry tools, measurement methods, and information processing. The issues of simulation of flight conditions during bench testing of liquid propellant engines, criteria of sufficiency of simulation are covered. To determine the causes of abnormal test outcomes, failure models are described using equations of dynamics of working processes in LRE units. Methods of structural-functional reliability analysis with account of flight test results are briefly described.