Time Between Overhaul as Related to Modern Engine Design and Maintenance Techniques

Time between overhauls (TBO) of above 2000 hr for certain Lycoming aircooled aircraft piston engines are shown to be practical through the use of modern engine design, materials, and maintenance technology, including the use of spectrograph oil analysis (SOAP). Several examples of extended time programs with their attendant problems are shown for a 150 bhp direct drive, 4-cyl engine and more sophisticated 380 bhp 6-cyl geared and 310 bhp turbocharged engines. Limiting TBO factors and practical limits of TBO are also discussed.