Using replacement fuel affects the maximum time between overhaul for the engine by what amount?

• A. 25 hr
• B. 1500 ft
• C. 30 C
• D. 10 hr

Answer: (A)

Using replacement fuel changes the operating environment inside the engine enough that maintenance planning adjusts how long you can go before overhaul. The maximum time between overhaul (MTBO) is set by how quickly critical components wear, and different fuels can alter combustion characteristics, deposits, and lubricity, which in turn affect wear rates. When replacement fuel is used as permitted by the engine’s maintenance guidelines, the schedule often allows a longer interval before overhaul. For this engine, the manual specifies an increase of 25 hours to the MTBO. In practice, always check the exact figures in the maintenance manual since the amount can vary by engine model and fuel specifications. The other options don’t fit because MTBO is measured in hours, not distance or temperature, and the listed adjustment is 25 hours in this scenario.