We offer replacement parts for our pieces.  The parts are designed to fit 16-18 models in most cases.

B-17 Flying Fortress Replacement Propeller, 1/69th Scale
B-17 Flying Fortress Propeller

NP2000 8 bladed props
NP2000 8 bladed props Designed to fit 18 inch models.  Order 3 and will send 4.

UH-1N Tail Rotors
Replacement tail rotor for H-1 series of 16 inch wooden models