Operating phase, scheduled inspections

Inspection before End of warranty

The inspection before end of warranty is a comprehensive technical inspection of the complete wind turbine including rotor blades. It serves in particular to determine defects before the warranty expires so that they can be claimed against the manufacturer in time.

Periodic inspection

The periodic inspection is usually required in the type approval and/or building permit and must be carried out regularly (usually every two to four years) in accordance with the requirements. The complete wind turbine is inspected.

Condition-based inspection

The condition-based inspection is prescribed by the insurance conditions of machinery breakdown and interruption insurance policies. It is a technical inspection of the entire wind turbine, supplemented by an offline vibration analysis of the drive train (offline CMS) and a lightning protection continuity measurement.


An offline vibration analysis of the drive train is used to detect changes in condition and to detect damage at an early stage, which otherwise can lead to unplanned downtimes.

Lightning protection continuity test

During the lightning protection continuity test, the resistance between the receptors of the blade and the grounding of the installation is measured. This is used to check whether, in the event of a lightning strike, the lightning protection system of the plant is functioning and the lightning current is reliably discharged into the ground.

Video endoscopy

The video endoscopy is used to inspect areas that are not accessible during a visual inspection. Usually raceways, rolling elements and cages of bearings as well as gearings are inspected.

Lifetime extension assessment

The evaluation on lifetime extension serves to determine potential reserves for extending the operating life over the calculated operating period of usually 20 years.