17.2 Propeller construction — materials, blade terminology, propeller types and installation
945 words · checked 2026-10-03 · Pro
Scope
A level 1, B1 level 2: construction methods and materials of wooden, composite and metal propellers; blade station, blade face, blade shank, blade back/thrust face and hub assembly; fixed-pitch, controllable-pitch and constant-speed propellers; propeller/spinner installation.
Blade terminology
| Term | Meaning |
|---|---|
| Hub | Central part attached to the engine shaft; holds the blades |
| Blade shank | Thick, round section of the blade near the hub — strong, little aerodynamic effect |
| Blade butt (root) | End of the blade that fits into the hub (with retention features) |
| Blade back | Cambered (curved) side of the blade, like the upper surface of a wing; faces forward |
| Blade face | Flat side of the blade, facing the pilot/rearwards |
| Leading / trailing edge | Thick front edge / thin rear edge |
| Blade tip | Outer end — highest speed, most prone to damage and erosion |
| Blade station | Distance (in inches or mm) measured outwards from the centre of the hub along the blade — used to locate blade-angle reference points, damage and repairs |
| Cuff | Aerofoil-shaped fairing on the shank of some blades, improving engine cooling airflow |
The EASA syllabus wording "blade back / thrust face" pairs the two terms; read questions carefully — in the FAA terminology used here, the back is the cambered side and the face is the flat side.
Wooden propellers
- Built from laminations (typically five to nine layers) of hardwood — birch most common (also maple, mahogany, ash) — glued with waterproof adhesive, shaped and varnished. Laminating prevents warping.
- Fabric sheathing (or plastic coating) on the outer blade section protects against moisture and erosion.
- Metal tipping (brass, Monel or terneplate) on the leading edge and tip, attached with screws/rivets; small drain holes in the tip let moisture escape and must be kept open.
- Fitted with a metal hub/adapter; bolts pass through the wooden hub — bolt torque must be checked regularly because wood shrinks and swells with humidity (check especially after changes of climate/season).
- Defects: cracks, elongated bolt holes, separated laminations, warping, charred hub face (slipping), moisture damage.
- Storage: horizontal position so moisture does not migrate to one blade.
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