Even in the jet age, propellers power a large part of aviation. Training aircraft, many general aviation aircraft and regional turboprops all depend on propellers, so mechanical engineers need to understand how they work and how to keep them safe.

How a propeller works

A propeller blade is a rotating wing. As it turns, it produces thrust in the same way a wing produces lift. The angle of the blade, called pitch, decides how much air it moves with each turn. Fixed-pitch propellers are simple, while variable-pitch and constant-speed propellers change blade angle to keep the engine at its most efficient speed.

Construction

Blades may be made of aluminium alloy, wood or composite materials, mounted in a hub that may contain a pitch change mechanism. Some propellers can be feathered, turning the blades edge-on to reduce drag if an engine fails, and some can produce reverse thrust to help slow the aircraft after landing.

Maintenance

Engineers inspect blades for nicks, cracks and erosion, dress minor damage within limits, check the pitch change system, balance the propeller to reduce vibration, and inspect de-icing systems. Correct storage and handling prevent damage when propellers are removed.

Learning it at Redwings

Module 17 covers propellers and is part of the B1 mechanical syllabus. Students link it with engine knowledge from Module 15 or 16 to understand the complete power plant.