How many levels of maintenance are performed on gas turbine engines?

• A. One
• B. Two
• C. Three
• D. Four

Answer: (B)

Two levels of maintenance are typically defined for gas turbine engines: field (on-wing or line) maintenance and depot (shop) maintenance. Field maintenance covers routine servicing, inspections, minor repairs, and troubleshooting that can be done while the engine is installed on the aircraft, allowing quick return to service. Depot maintenance takes place in a dedicated facility and involves thorough disassembly, detailed component inspections, repairs or replacements of worn parts, balancing, and comprehensive testing to restore the engine to serviceable condition. This split into on-aircraft work versus complete overhaul explains why the correct choice is two. A single level wouldn’t address both quick-turn tasks and major overhauls, while three or four levels add subdivisions not typically used in this standard framework.