Have you heard of hand propping? If so, you might be wondering how it works.
Most propeller-driven airplanes are equipped with an electric starter. After turning on the fuel selector and setting the throttle to idle, pilots can activate the electric starter. The electric starter will then spin the propeller and ignite the fuel-air mixture for combustion. If the electric starter fails, however, hand propping may offer an alternative solution.
Overview of Hand Propping
Hand propping is the colloquial term used to describe the process of manually starting a propeller engine. It’s typically used with smaller propeller-driven airplanes, particularly those that lack an electric starter. Hand propping involves grabbing and turning the propeller by hand to start the engine.
Hand propping dates back to aviation’s early days — long before electric starters became standard. While most modern planes are equipped with automated systems, hand propping still plays a role for enthusiasts flying older or specialized aircraft.
How Hand Propping Works
Hand propping works by forcing the engine to fire as the propeller turns. Prior to hand propping, the pilot will typically perform safety checks, such as ensuring the brakes are engaged and the wheels are chocked to prevent unwanted movement. The pilot may also set the throttle to a low position.
After performing a series of safety checks, the pilot will move the propeller to the appropriate position. This is typically just past the compression stroke. At this position, the propeller will generate the most force possible. Next, the pilot will manually turn the propeller through its rotation. The engine should then fire, at which point the propeller will continue to turn on its own.
Safety Considerations
Hand propping requires extreme caution. Airplane propellers typically aren’t razor-sharp, but the power and speed at which they turn can cause bodily injury.
Most instances of hand propping involve two people, such as the pilot and copilot. One person will turn the propeller, whereas the other person performs controls in the cockpit. The person turning the propeller may ask the other person to turn off or lower the throttle. Performing this manual starting process with two people lowers the risk of incidents.
Fortunately, most propeller-driven airplanes don’t require hand propping. As long as an airplane has an electric starter — and the starter works — hand propping isn’t necessary.
