FAA Powerplant Written Practice Test

Before removing a cylinder from an engine, where should the piston be positioned?

1. At bottom dead center.

2. Top dead center following the compression stroke.

3. Mid-stroke position.

4. Fully extended position.

The correct answer is: Top dead center following the compression stroke.

The correct position for the piston before removing a cylinder from an engine is at top dead center following the compression stroke. This position is crucial for several reasons. When the piston is at top dead center (TDC), it is at its highest point in the cylinder. This minimizes the risk of any debris or foreign objects falling into the combustion chamber and possibly damaging the piston or cylinder walls during removal. Additionally, positioning the piston at TDC after the compression stroke ensures that the cylinder is not under pressure, which reduces the likelihood of injury or complications when you detach the cylinder head and work on the engine. Being at TDC also allows more space inside the cylinder. If the piston were at bottom dead center or mid-stroke, it could interfere with components like the valves or the cylinder head itself, complicating the removal process. The fully extended position is similarly unsuitable as it does not provide the necessary clearance or safety. Therefore, after the compression stroke, TDC is the optimal position for safe and effective cylinder removal.