NDT in aviation: where the borescope fits among the methods

The methods

• Visual and remote visual inspection: the inspector's eyes, aided by lighting, mirrors and magnifiers; a borescope extends visual inspection into gas paths, ducts and cavities that cannot be reached directly.
• Liquid penetrant inspection (FPI/DPI): a dye drawn into surface-breaking cracks on non-porous parts such as turbine blades and disks once they are removed and cleaned.
• Magnetic particle inspection: surface and near-surface cracks in ferromagnetic parts such as landing gear and shafts.
• Eddy current: surface and near-surface cracks and corrosion in conductive materials, including around fastener holes and blade roots, without removing paint.
• Ultrasonic testing: internal flaws, bond lines and thickness, using sound waves; common on composites and thick sections.
• Radiography: X-ray or gamma imaging of internal structure, castings and welds.
• Thermography and other methods: infrared for disbonds and water ingress in composites; shearography and acoustic methods for specific structures.

Where the borescope fits

On an installed engine, the borescope is the primary method. It reaches the fan, compressor, combustor and turbine through dedicated ports, records what it sees on video, and lets the inspector size a finding against the maintenance manual limit. When a borescope finding needs confirmation — a suspected crack on a turbine blade, for example — the part comes out and a surface method such as penetrant or eddy current gives the definitive answer.

Who is qualified

NDT methods such as penetrant, eddy current and ultrasonic are performed by personnel certified under schemes like NAS 410 or EN 4179. Borescope inspection of engines is usually carried out by licensed or authorized engine technicians under the operator's or maintenance organization's procedures, with training on the engine type and the equipment. Ask any provider which applies to the work you need.

What a good NDT report has in common

The method, the equipment and its calibration, the procedure and acceptance criteria, the area inspected, each finding with its size and location, the result, and the signature and certification of the person who did the work. A borescope report has exactly the same shape.