The color coding of prop-rotor blades (red, green, white) is used to differentiate between which blades?

• A. Left and Right blade sets
• B. Fore and Aft blades
• C. Inner and Outer blades
• D. Upper and Lower blades

Answer: (A)

Color marking on prop-rotor blades is a quick visual cue to identify which blades belong to the left-hand set versus the right-hand set. With multiple blades on a rotor, each blade has a specific position and balance contribution. The red, green, and white markings help maintenance crews reinstall each blade in its original side and position, preserving the rotor’s balance, tracking, and aerodynamic phasing. Swapping blades between the left and right sets can change the overall balance and vibration characteristics, so the color code helps prevent that. These markings don’t denote fore-aft, inner-outer, or upper-lower relationships; they specifically differentiate blade sets by side.