FAA Powerplant Written Practice Test

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Prepare for the FAA Powerplant Written Test. Study with flashcards and multiple choice questions, each featuring hints and explanations. Ace your exam with confidence!

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What is a primary purpose of the run-in procedure after overhauling a piston engine?

To check for oil leaks
Seating the piston rings and burnishing the crankshaft bearings
To ensure correct fuel mixture
Testing engine performance under load

The correct answer is: Seating the piston rings and burnishing the crankshaft bearings

The primary purpose of the run-in procedure after overhauling a piston engine is to seat the piston rings and burnish the crankshaft bearings. During this phase, the engine is operated in a controlled manner to allow the components to wear into their proper shape and fit. Seating the piston rings is critical for ensuring that they achieve a proper seal against the cylinder walls, which directly affects the engine's compression and overall efficiency. This process helps to optimize the ring-to-cylinder wall interface, thereby improving performance and reducing oil consumption. Burnishing the crankshaft bearings involves running the engine under specific conditions to create a smooth and hardened surface on the bearings. This significantly enhances their lifespan and operational reliability. The run-in process is designed to promote the best possible performance characteristics of the engine before it enters normal operational use.