FAA Aviation Mechanic Powerplant (AMP)PropellersEasy
A vintage aircraft is equipped with a wood propeller. Which construction feature is specifically used to protect the wood laminations from moisture absorption and warping?
- AA foam-filled cavity sealed with epoxy resin
- BA hollow steel spar running through the center of each blade
- CA fabric or plastic covering with metal leading-edge tipping and a protective varnish finish
- DAn electrothermal heating element bonded to each blade surface
Show answer & explanationAnswer & explanation
Correct answer: C. A fabric or plastic covering with metal leading-edge tipping and a protective varnish finish
Wood propellers are laminated from several layers of wood glued together, then covered with fabric or plastic and finished with varnish, with metal tipping on the leading edge to resist erosion and moisture intrusion. Steel spars, foam cores, and heating elements are not part of traditional wood propeller construction.
Why the other options are wrong
- A. Foam-filled cavities are not used in solid laminated wood blades.
- B. Wood propellers do not contain internal steel spars.
- D. Electrothermal heating elements are used for ice protection, not moisture sealing.
Wood Propeller Construction
A wood propeller is built from multiple laminated wood layers glued together, covered with fabric or plastic, varnished, and fitted with metal leading-edge tipping to protect against moisture and erosion.
- Laminated wood layers glued together
- Fabric/plastic covering with varnish finish
- Metal tipping protects leading edge
- Sensitive to moisture and requires careful storage
Memory trick: Wrap it, varnish it, tip it in metal — keep the wood dry and whole.