Drone inspection of wind turbines – on- and offshore

Wind turbine towers and rotor blades are exposed to the whims of the weather. Drone inspection provides a visual or thermographic image of the state of the components.

Benefits of drone inspection

Hail, snow, lightning, rain, salt and dust are just some of the things wind turbine components must endure. Using our drone inspection solution for visual inspection of on- and offshore wind turbines provides benefits such as:

safe working environment
reduced downtime
high quality images and video
access to otherwise inaccessible areas
dynamic surveying
preventive maintenance planning.

A drone inspection is a cost-effective and efficient inspection method compared to traditional telephotography or other manual inspection methods. With a drone inspection solution, you can achieve both visual and thermal images on wind turbines for on-site analysis and assessment regarding the condition of the rotor blades.

Digital and/or infrared camera inspection

When inspecting wind turbines, the drone can be equipped with a digital camera, a thermographic camera or a combination, depending on the scope of the inspection task. A digital camera provides proof of the visual failures and damages of the tower, nacelle, rotor blades and bolt jointings.

Thermographic inspection is a non-contact and non-destructive inspection method that makes it possible to examine a large area of the blade for structural defects and weaknesses in the blade. With infrared thermography, the drone monitors variations in the surface temperature of e.g. the rotor blades.

Infrared thermography is a powerful technique for subsurface examination of wind turbine rotor blades. — The temperature profile of e.g. the blade surface indicates potential defects.

Benefits of infrared thermographic images:

Non-contact and non-destructive inspection methods
Visualisation of temperature on large areas of e.g. the rotor blade for comparison
Examination, measurement and observation of inaccessible or dangerous area
Detection of hidden defects and failures
Detection of objects in dark areas
Detection of erosion and corrosion
Examination of abnormalities.

On-site rotor blade inspection

During an on-site inspection, our investigation team will fly the drone to the required position for data capture and start the inspection of the rotor blade, whether it is for a full inspection or specific areas of the rotor blade. The data is stored, making on-site evaluation of the state of the wind turbine possible. The drone lies stable in the air and can handle a wind speed of up to 10 m/s. Therefore, the drone is ideal for inspection of both onshore and offshore wind turbines.

Drone inspection of wind turbine blade — A drone inspection reveals damages to the wind turbine blade and ensures that repairs are carried out in time.

Only experts ought to analyse data

During the aerial inspection, a FORCE Technology pilot operates the drone. During the flight, our certified NDT personnel usually operate the camera, record video and direct the pilot to the points of special interest and views of different angles of the tower, nacelle, rotor blades and bolt jointings.

Under normal circumstances, the drone inspection itself is quickly finished. The heavy workload lies in the analysis of the collected data, and the pictures taken by the drones. It is essential here to enlist relevant experts in analysis to obtain the full value from a drone inspection. Someone lacking the necessary qualified experience may overlook a critical defect or fault, possibly with fatal consequences.

An inspection report is produced, based on the analysis of this data, and is usually divided into categories of red, yellow and green priority according to the seriousness of the damage. This report can if needed include a service plan, with recommendations to cost-effective improvements.

At FORCE Technology, we only use drones when we conclude that it is the optimal solution. Based on our extensive experiencewith and knowledge of all types of inspections, we always offer the best solution, tailored made for the job – with or without a drone.

FAQ

Where can drone inspection be applied?
Drone inspection can be applied anywhere outdoor, indoor and offshore. A drone inspection improves operator safety, as they are situated at a safe distance from the inspection.

The method improves safety, as everyone are situated at a safe distance from the inspection area.
How high can the drone fly?
Normally, drones are restricted to flying at an altitude of 100 meters. However, FORCE Technology is authorised to carry out inspections higher than 100 meters.
What kind of non-destructive testing (NDT) techniques can be used during drone inspection?
Currently, it is only possible to perform visual inspection (VT). However, visual inspection is more than still images and video recordings.

When inspecting wind turbines, we use an advanced thermographic camera which can detect delaminations as well as internal composite layers separating beneath the blade surface.

The drone can also be equipped with an advanced data collecting equipment, making it capable of measuring flue gas emissions from ships and methane gasses from landfills.
Are the FORCE Technology drone pilots certified?
Yes. Our drone pilots are certified. Combining autonomous drones with skilled and certified NDT personnel and pilots, ensures a rapid yet thorough visual or thermal inspection.

Furthermore, our drone fleet consists of multiple drones equipped with sensors for inddoor and outdoore inspection and 3D modeling tools for the mapping of production sites.
What about national or local regulation and safety procedures?
Any requirements from national or local regulation as well as the safety procedures of the facility owner are complied with when we perform the drone inspection.

A drone pilot is always present during the inspection job due to safety procedures and local regulations. However, in principle, the drone can inspect all relevant installations without continuous instructions from a pilot. This is due to the drone’s navigation systems.

As a drone inspection can be influenced by numerous parameters, we always recommend a meeting between the client and the pilot/inspector before the inspection to ensure that all relevant national or local details are addressed.
Who analyses the inspection data?
We believe that only experts ought to analyse the collected data. Under normal circumstances, the drone inspection itself is quickly finished. The heavy workload lies in the analysis of the collected data, and the pictures taken from the drones. It is essential here to enlist relevant experts in analysis to obtain the full value from a drone inspection.

Someone lacking the necessary qualified experience may overlook a critical defect or fault, possibly with fatal consequences. For instance, an inspection concerning a steel construction requires an expert metallurgist to analyse and interpret the data.

An inspection report is produced, based on the analysis of this data, and is usually divided into categories of red, yellow and green priority according to the seriousness of the damage. This report can if needed include a service plan, with recommendations to cost-effective improvements.

Inspection using drone technology provides access to hard-to-reach areas with a high level of safety.

Ronni Bing Simonsen

Engineer, Special Testing, Tank Inspection & Technical Consultancy

T. +45 42 62 79 65 Contact Ronni

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Authorizations

FORCE Technology has been approved by Civil Aviation Authorities to conduct drone operations in the following countries:

Denmark (AIC B 08/14)
Sweden (TSFS 2009:88)
Norway (AIC N 14/13)

If the inspection is not carried out in one of these countries, we will simply obtain a license in the desired country. Drone inspections are always conducted in accordance with local regulations.