Visual inspection VT1–VT3, finding categories and what 4K + LiDAR deliver in professional finding documentation. Normative fundamentals, classification systems and practical application – from the Kopterflug perspective.
The Visual Testing (VT) is the fundamental non-destructive testing method – and the one most profoundly transformed by drone deployment. It is normatively regulated in DIN EN ISO 17637 (visual examination of fusion-welded joints) and DIN EN 13018 (general principles for visual examination). For qualification of testing personnel, DIN EN ISO 9712 applies.
In drone inspections a distinction is made: the drone pilot carries out the image capture – he does not necessarily need to be VT-qualified. Finding assessment requires a VT2/VT3 qualification. In practice, Kopterflug has both certified pilots and NDT-qualified personnel in the team who conduct the evaluation.
DIN EN 13018 distinguishes between direct visual examination (inspector has direct visual contact with the surface, maximum eye distance 600 mm, illumination min. 500 lux) and indirect visual examination (using optical aids such as endoscopes, mirrors – or drone video systems).
Drone inspection is classified as indirect visual examination in current professional practice. This means: findings that go beyond the indirect VT and require measurement-based evaluation (e.g. wall thickness measurement, crack length measurement) must be supplemented by additional testing methods (UT, MT, PT). The drone provides the orientation – it shows exactly where testing must be conducted.
In industrial inspection there is no uniform finding classification system – various norms, regulations and operator specifications define different categories. Kopterflug follows the most common systems:
For pressure vessels and tanks we follow API 510 (Pressure Vessel Inspection Code) and API 653 (Tank Inspection, Repair, Alteration, and Reconstruction):
In German regulations (BetrSichV, TRBS 1112) a distinction is made between defects (remediable defect without immediate danger) and significant defects (immediate action required). Authorised inspection bodies (ZÜS) such as TÜV, DEKRA or BÜV also use their own evaluation systems.
For finding documentation at Kopterflug: every identified finding receives a unique finding ID, a GPS/LiDAR localisation in the 3D model, photo documentation from the 4K material and an initial assessment category. The final categorisation is the responsibility of the commissioned expert or ZÜS.
Crack in a weld seam – precisely localised in the 3D model, documented at the finding level, categorised per API/BetrSichV.
A complete finding report from a drone inspection contains significantly more than a conventional handwritten inspection report. The following elements are standard:
The finding report is a legally relevant document. For inspection-mandatory plants per BetrSichV Appendix 2, documentation must meet the requirements of TRBS 1201. The retention obligation is generally the lifetime of the plant plus 5 years. Drone video material and 3D scans supplement the written report – they are not a replacement but an extension.
The quality leap compared to conventional visual inspection lies in the reproducibility and completeness of documentation. An inspector climbing a ladder can take 100 photos – but he cannot position the camera at every spot, and his photos are neither georeferenced nor usable as complete geometry documentation.
LiDAR adds a dimension to documentation that cannot be achieved with camera data alone: geometry. The point cloud of the Ouster OS0-32 scanner in the ELIOS 3 has an accuracy of ±3 cm for typical industrial plants. This enables:
This combination of visual documentation and 3D geometry makes the drone finding report the most comprehensive inspection document currently available for confined space applications.
Dipl.-Ing. Karsten Lehrke and Christian Engelke – your direct contacts for professional drone finding documentation.
We advise on norm-compliant documentation – from finding categorisation to integration into BetrSichV/TRBS documentation requirements. Our finding reports are designed as a basis for certified inspectors and authorised inspection bodies.
Direct visual testing: the inspector has direct visual contact with the surface, maximum eye distance 600 mm per DIN EN 13018. Indirect visual testing: testing via optical aids (endoscopes, drones, cameras). Drone inspection is classified as indirect visual testing. Findings requiring measurement-based evaluation (crack length, wall thickness) must be supplemented by further NDT methods.
The pilot does not necessarily need VT qualification for conducting the image capture. Finding assessment requires VT2/VT3 qualification per DIN EN ISO 9712. In practice Kopterflug has NDT-qualified personnel who evaluate the drone footage and create the finding documentation.
We orient ourselves to the most commonly used systems for the respective plant type: API 510/653 for pressure vessels and tanks, DIN EN 13018 for general visual testing, and BetrSichV/TRBS for German regulatory requirements. The final categorisation is always by the commissioned expert or authorised inspection body (ZÜS).
During post-processing in Flyability Inspector, findings are marked directly in the 3D point cloud with position coordinates. This creates a unique spatial reference – each finding has X/Y/Z coordinates that are reproducible at the next inspection. The finding can be found in the 3D model by navigating to its coordinates.
No – but it is an excellent preparation and documentation foundation. The drone finding report documents the visual condition systematically with 4K and 3D data. The expert report by a ZÜS (authorised inspection body) is a regulatory requirement for mandatory inspections per BetrSichV. The drone data significantly supports the expert in his assessment.
Typically 2–5 working days after the inspection, depending on plant complexity and number of findings. For urgent assessments we can provide a preliminary report with key findings within 24 hours. The final report with complete 3D model and annotated finding documentation follows within the standard lead time.
We communicate critical findings immediately – without waiting for the final report. You are informed on-site or by phone on the day of the inspection. Category A findings are specifically highlighted in the preliminary report and are immediately submitted to the responsible expert or operator for decision-making.
Drone-based visual inspection (VT) is increasingly accepted as a documentation method. The legal recognition depends on the specific regulatory context: for voluntary condition monitoring it is unproblematic; for mandatory inspections per BetrSichV, acceptance by the responsible ZÜS must be clarified in advance. We clarify this before the inspection.
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