Which method is used to contour damaged blades and vanes?

• A. Laser trimming
• B. Ultrasonic shaping
• C. The hand method
• D. Computer numerical control milling

Answer: (C)

Restoring the exact aerodynamic shape of a damaged blade or vane relies on precise, localized material removal with careful control. The hand method gives the technician intimate control over every pass, allowing small, incremental shaping while constantly referencing templates and measurement devices. This tactile feedback makes it possible to reproduce the original contour and maintain the correct thickness at critical sections, which is essential for maintaining proper clearance, aerodynamics, and structural integrity after repair.

Other methods introduce challenges: heat from laser trimming can cause microstructural changes and warping, and CNC milling, while fast, can be too aggressive for fine, localized contour work and may leave tool marks or alter the blade’s delicate features. Ultrasonic shaping isn’t the standard approach for final airfoil contouring in overhaul practice.