Glossary
TBO (Time Between Overhaul)
Definition
The manufacturer's recommended engine operating time before a major overhaul. Not legally binding for Part 91 operations but strongly followed by most schools and insurance companies.
Why It Matters
TBO for common training engines (Lycoming O-320, O-360) is typically 2,000 hours. Approaching TBO affects aircraft value, insurance, and scheduling decisions. Some schools operate past TBO with oil analysis and condition monitoring.