That streamlined, usually conical housing over the hub of your airplane’s propeller is not there for its contribution to the aircraft’s rakish good looks—the prop spinner has an important job to do.
The spinner exists to smooth the airflow as it enters openings in the cowling to provide proper engine cooling. A spinner is required equipment on the majority of the airplanes we fly, and the engine should not be operated if the spinner is not present and properly installed.
On your preflight inspection, ensure that the spinner is attached securely in place, and make sure there are no cracks—especially around the mounting screws. A cracked spinner is unairworthy. Check carefully for loose or missing screws, and never push on the spinner to move the airplane, even if you’re only checking the nosegear strut.
When preflighting an airplane that’s tied down outside during freezing temperatures, rap your knuckles on the spinner as you move your hand around it. If the sound changes, it indicates that water trapped inside the spinner has frozen into ice, which will cause vibrations when the engine is running.
While around the spinner, look for any fluid leaks, as well as secure attachments of the blades and any other propeller hardware.
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