<div class="htmlview paragraph">Durability of a current production rotary engine was evaluated while operating on natural gas. Through regular scheduled teardown inspections, wear data was gathered on critical engine components and used to develop component wear trends. Wear trends were used to predict the usable life of the engine before requiring a major rebuild. Preliminary results indicate apex seal wear rates and trochoid wear rates low enough to achieve 20,000 hours of engine operation. Areas requiring further durability improvement include the ignition system and optimization of the oil injection. Advanced knowledge of current engine component durability will be used to accelerate the development of novel gas fueled rotary engines currently under development in the United States.</div>