What is the purpose of a thorough engine run-up before takeoff?

The purpose of a thorough engine run-up before takeoff is primarily to check engine instruments and systems for proper operation. During the run-up, the pilot conducts a series of tests that evaluate the engine’s performance, ensuring that all instruments are functioning correctly, and that there are no anomalies in engine operation. This can include examining parameters such as oil pressure, temperature readings, RPMs, and magneto checks to confirm that the engine is running smoothly and within the required limits.

Performing this check is crucial for ensuring safety, as it allows the pilot to identify any potential issues before committing to flight, where an engine failure could have serious consequences. A proper engine run-up contributes to a well-informed decision about whether the aircraft is fit for takeoff. Other options, such as demonstrating flight skills to passengers or testing engine endurance, do not accurately reflect the safety and operational intentions behind performing an engine run-up. Similarly, determining weight and balance is important but pertains to different pre-flight checks and is not a function of the engine run-up.