Simulated Flight Endurance Testing of a Small Helicopter Turboshaft Engine

Several simulated flight endurance (SFE) tests of 500, 1000 and 1500 hours duration have been accomplished on a small helicopter turboshaft engine series. These tests originated in 1964 using a test cycle based upon U.S. Army Light Observations Helicopter (LOH) mission profiles. They have evolved to their current form which more closely simulates the installation environment and better represents the duty cycle that the engine has experienced in military and commercial flight service. This testing has been used to help establish engine overhaul periods and ultimate parts life, and to evaluate design modifications. An automatic engine control and monitoring system was designed and developed to provide economical, unmanned operation of the engine. An automatically-programmed shaker imposes a simulated helicopter vibration environment upon the engine during SFE running. The results of these SFE tests have proven particularly valuable in revealing potential engine problems related to durability and in evaluating the effectiveness of modifications designed to correct these problems.