Drone Wind Turbine Inspection Services in India

Geocartis inspects wind turbines across India: all twelve blade surfaces at defect-level resolution, tower and coating condition, nacelle exterior, foundation and plinth, and the wider site. Findings come back classified by severity and addressed to turbine, blade and position along the span, with imagery linked. Nobody goes up a rope, and each turbine is stopped for a fraction of the time any other inspection method requires. We are based in Ahmedabad and work nationally.

We are a survey and inspection services company. We do not build drones, we do not sell software, and we do not carry out repairs.

Why blades

A wind turbine has plenty of components that fail, and most of them are inside the nacelle where a camera cannot go. Blades are different. They are the largest, most expensive single components on the machine, they are exposed to everything, they degrade continuously, and their condition is visible from outside.

They also degrade in a way that costs money before it costs a failure. Leading edge erosion, the gradual pitting and stripping of the blade’s leading edge by rain, dust, sand and insects, changes the aerofoil and reduces aerodynamic efficiency across the whole blade. Industry and OEM guidance generally puts the annual energy production loss from significant leading edge erosion in the low single-digit percentages, and on a fleet that is a substantial number that never appears as a fault code.

In India the erosion picture is harsher than in temperate climates. Coastal salt air on the Gujarat and Tamil Nadu coasts, airborne dust and sand in Kutch and Rajasthan, and monsoon rain at high tip speeds all attack the leading edge. Turbines here erode faster than the design assumptions of machines engineered elsewhere.

The other blade findings, cracks, bond line failures, lightning strike damage, delamination, are less common and much more consequential. A transverse crack that goes unrepaired becomes a blade failure, and a blade failure is a component replacement with a crane, which is the single most expensive routine event in a wind farm’s life.

The argument for regular inspection is straightforward. Erosion caught early is a coating repair. Erosion left is a leading edge protection system replacement. A crack caught early is a laminate repair from a platform. A crack left is a new blade and a crane.

The downtime arithmetic

This is the part that decides the purchase, and it is worth setting out with numbers.

Blade inspection requires the turbine to be stopped, the rotor parked and locked, and the blades pitched to present their surfaces. That means lost generation, and lost generation is the real cost of any inspection method.

Rope access. A rope team inspecting all three blades on one turbine occupies most of a day, and often more than one. On a 2 MW machine running at a 25 percent capacity factor, averaging 500 kW, a full day of downtime is around 12,000 kWh. At ₹3 per kWh that is roughly ₹36,000 of lost revenue, per turbine, before the rope team’s own cost.

Drone inspection. All twelve blade surfaces captured in a stop measured in tens of minutes rather than days. On the same machine, half an hour of downtime is around 250 kWh, or roughly ₹750.

Those figures are illustrative and your capacity factor and tariff will differ, but the ratio is the point. The generation you lose to a drone inspection is close to a rounding error against what you lose to rope access, and that is before the safety difference between somebody hanging off a 100 metre tower and somebody standing at its base.

And it compounds across a fleet. A rope programme covering fifty turbines is a season’s work. A drone programme covering fifty turbines is a matter of weeks, which is why complete fleet coverage becomes affordable rather than aspirational.

Scheduling still matters. We plan campaigns for the low-wind season and, within that, for the low-wind part of the day, because downtime that coincides with a period the turbine would not have generated much anyway costs almost nothing. On Indian sites that generally means avoiding the monsoon months on the western and southern coasts, which is also when flying conditions are worst.

What we inspect

Blades

Twelve surfaces per turbine: pressure side, suction side, leading edge and trailing edge on each of three blades. All twelve are captured on a standard inspection, and each defect is located by blade, surface and distance along the span from root to tip.

Findings we report: leading edge erosion with extent and depth category, transverse and longitudinal cracks, trailing edge bond line separation, shear web and bond line indications visible externally, delamination and blistering, gelcoat and coating damage, pinholes and surface porosity, lightning strike damage and receptor condition, lightning down conductor damage where visible, tip damage, drainage hole condition and blockage, vortex generator and serration damage or loss, repair condition where previous repairs exist, and surface contamination and soiling.

Tower

Coating condition and breakdown, corrosion, weld appearance at external seams, external flange condition, ladder and platform external fixings, lightning protection and earthing where externally visible, door and access hatch condition, aviation lamp condition, and any impact or physical damage. Tower verticality can be assessed where the scope includes it, though the accuracy that gives you is coarser than a survey instrument and we say so.

Nacelle

Exterior only. Roof and cover condition, panel gaps and damage, anemometer and wind vane condition and mounting, aviation lighting, lightning protection, external oil traces indicating a leak, and hatch condition. Nothing inside the nacelle is within reach of a drone.

Foundation and plinth

Concrete surface condition and cracking, grout condition at the tower base, water pooling and drainage, visible settlement, exposed anchor bolts and their condition where visible, and erosion around the foundation.

Site level

Access road condition and washouts, crane pad condition, cable trench routes, erosion and drainage across the site, vegetation, boundary and encroachment, and the substation and switchyard exterior. On hilly sites in Maharashtra, Karnataka and Tamil Nadu, road and crane pad condition is not incidental, because it determines whether a crane can reach a turbine when it needs to.

Repowering and life extension

The Indian policy context creates a specific demand that is worth understanding.

MNRE issued the National Repowering and Life Extension Policy for Wind Power Projects on 7 December 2023, superseding the 2016 repowering policy. The National Institute of Wind Energy has put the country’s repowering potential at 25.406 GW considering turbines below 2 MW.

Eligibility under the policy covers turbines not compliant with the ministry’s quality control order, turbines that have completed their design life as certified under the type certificate, turbines requiring replacement within design life due to malfunction, workmanship or safety issues, turbines rated under 2 MW, and turbines after fifteen years of installation on commercial or voluntary consideration. A project qualifies as repowering or refurbishment where annual generation is enhanced by at least 1.5 times the earlier generation, and it must be operational within 24 months of the consent letter.

The line that creates the work for us is in the life extension provision. Refurbishment for life extension is undertaken by the developer with the consent of the state nodal agency, and the turbine is to be assessed and certified by the certification agency for quality and safe operation.

That assessment needs condition data on the structures, and blade and tower condition are a substantial part of it. On a fleet of fifteen or twenty year old sub-megawatt machines, the owner facing a repower-or-extend decision needs to know what physical state the assets are actually in, and for most of those fleets nobody has looked properly at the blades in years.

To be clear about our role. We are not a certification agency and we do not issue the certification the policy requires. That is for the designated certification bodies. What we provide is the condition survey that feeds the assessment, in a form a certification body or an independent engineer can use.

State-level implementation varies considerably and is worth checking for your site. Tamil Nadu introduced a dedicated policy in 2024 mandating repowering for turbines older than twenty years regardless of size, and set up a dedicated agency. Karnataka relies on the MNRE guidelines. Gujarat and Maharashtra have, as of recent analysis, not issued their own repowering policies or definitions, which leaves developers in those states working from the central policy.

What a drone inspection is not

Not internal blade inspection. The inside of a blade, the shear webs, the internal bond lines, the down conductor run, is inspected with crawler robots or by a technician entering from the root. External imaging tells you nothing about it, and some of the most serious blade defects begin internally.

Not non-destructive testing. Visual and thermal capture does not measure laminate thickness, does not detect subsurface delamination reliably, and does not replace ultrasonic, tap testing or shearography. A blade surface that looks sound has not been tested.

Not certification. We do not certify blade condition, structural integrity, remaining life, or fitness for continued operation. Those determinations belong to a certification body, the OEM, or a qualified blade engineer.

Not gearbox, generator, bearing or drivetrain condition. Those are vibration analysis, oil analysis, borescope and SCADA territory, entirely inside the nacelle.

Not a substitute for a competent blade engineer’s judgement. We classify what we observe against a severity scale. Whether a Category 3 finding on a particular blade type at a particular span position warrants immediate action, monitoring or scheduled repair is an engineering decision informed by the blade’s design, its history and the operator’s risk position.

How we do it

Step 1: Fleet data and campaign planning

We ask for the turbine list with make, model, rating, hub height, rotor diameter and commissioning date, the site layout, previous inspection reports, known repairs and their locations, blade serial numbers where available, and any history of lightning strikes or SCADA anomalies.

Previous repairs matter particularly. A repair that was done three years ago and is now debonding looks different in a report if the inspector knows a repair exists there, and it is one of the more common findings on older Indian fleets.

Campaign planning then sets the sequence: which turbines, in what order, over how many days, and around what wind conditions. On a large fleet we plan for the season rather than the day.

Step 2: Coordination with the operator

Blade inspection requires the turbine stopped, the rotor parked and locked in the agreed position, and the blades pitched. That is the operator’s action, carried out by their qualified personnel to their own lock-out procedure, and it is coordinated turbine by turbine through their control room.

We plan the sequence so that turbine stoppage is as short as possible and turbines are brought back online as soon as capture is complete rather than at the end of the day. On a campaign covering many machines, that scheduling discipline is worth real money to the owner.

Site induction, permits and the operator’s safety rules apply throughout.

Step 3: Airspace

We check the site against the Digital Sky airspace map before quoting. Green zone to 120 metres above ground level without prior flight permission, yellow zone with permission and a lower ceiling, red zone not at all.

This one deserves attention on wind sites. A modern turbine has a hub height around 100 metres or more and a blade tip reaching well above that. Inspecting the top of a turbine can require flying above the 120 metre green zone ceiling, which needs specific permission. On older sub-megawatt machines with hub heights of 50 to 80 metres this is not an issue. On new large machines it can be, and it is checked at quotation rather than discovered on site.

Wind sites in Kutch, Jaisalmer and coastal Tamil Nadu can also sit in border or restricted airspace.

Our aircraft carry active Unique Identification Numbers and our pilots hold DGCA Remote Pilot Certificates.

Step 4: Flight planning and resolution

Blade inspection is close-range work at a fixed standoff, not a mapping flight. The aircraft flies a defined path along each blade surface at a set distance, capturing overlapping images at consistent scale.

Resolution is the specification that matters. Detecting small surface defects on a blade needs a ground sample distance at the blade surface commonly in the region of half a millimetre to one millimetre per pixel, which is achieved through a combination of standoff distance and lens. Coarser than that and small cracks, pinholes and early erosion are simply not resolvable, however good the report looks.

We state the achieved resolution in every inspection report. A blade inspection report that does not tell you the image resolution at the blade surface cannot be assessed for whether it would have found what it did not find.

A full inspection of all twelve surfaces on one turbine produces a substantial image set, in the low hundreds of frames, indexed by blade, surface and span position.

Step 5: Capture

Wind is the operational constraint. A parked rotor still moves slightly, blades flex, and the aircraft is working close to a large structure in the turbulence it creates. There are wind limits beyond which we do not fly close to a blade, and they are lower than the limits for open mapping work.

Light matters. Direct hard sunlight on a white blade surface produces glare and blown highlights that hide exactly the fine surface detail being looked for. Overcast conditions are often better for blade imaging than clear sun, which is one of the few cases where cloud helps.

The aircraft never touches the structure and maintains a standoff appropriate to conditions. Where wind or turbulence make the standoff unsafe, the pass is aborted and repeated rather than pushed.

Take-off and landing sit clear of the turbine base and clear of the rotor’s swept area.

Step 6: Analysis and classification

Images are reviewed and defects identified, then classified.

Severity classification in this industry commonly uses a five-category scale running from cosmetic observations through to damage requiring immediate action, though the precise definitions vary between owners, OEMs and service providers. We work to your scale where you have one, and to a clearly defined scale of our own where you do not, with the definitions printed in the report so that a Category 3 in our report means something specific rather than something implied.

Each finding carries: turbine ID, blade, surface, distance from root along the span, defect type, severity category, dimensions where measurable, the image, and a note where the finding needs closer examination.

We distinguish observation from diagnosis. A dark line on a blade surface may be a crack, a repair edge, a lightning down conductor trace or surface contamination. Where the image does not resolve the ambiguity, the finding says so and recommends verification, rather than being resolved in whichever direction makes the report look more decisive.

Step 7: Reporting

The deliverable is a defect register with imagery linked, sortable by turbine, blade, severity and defect type, plus a fleet summary that shows how many findings of each severity exist and where they are concentrated.

On a repeat programme the report also shows findings that are new, findings that persist, findings that have progressed in severity since the last campaign, and findings that have been repaired. Progression is the most useful column, because a Category 2 erosion patch that became a Category 3 in twelve months is telling you about your erosion rate and therefore about when the rest of the fleet needs attention.

Deliverables and output file formats

Raw imagery is handed over with the deliverables.

Other wind work

Pre-construction site survey. Terrain model, access road and crane pad design support, and the site layout survey for a proposed wind farm or hybrid park.

Construction monitoring. Foundation and plinth construction, tower section and component laydown, crane pad works, access road progress, erection progress across the site, and internal cable route works. Our construction survey page covers the method.

Post-lightning and post-storm assessment. Rapid inspection after a strike or a cyclone, with damage documented for warranty or insurance purposes and a dated record.

Wind-solar hybrid sites. Where a site carries both, the same visit can cover turbine inspection and solar thermal inspection, which is meaningfully cheaper than two mobilisations. Our solar inspection page covers that side.

Evacuation line inspection. Wind farms come with collector networks and evacuation lines, and the same visit can cover those. Our power line inspection page covers it.

Where we work

We are based in Ahmedabad, in the state with the largest wind fleet in the country, which puts a substantial share of India’s turbines within reach of our base.

Gujarat. The Kutch belt including the Khavda area, Jamnagar, Dwarka, Porbandar, Rajkot, Bhavnagar, Surendranagar and Banaskantha. Gujarat also carries a large population of older sub-megawatt machines, which are exactly the fleet facing the repower-or-extend decision.

Tamil Nadu. Muppandal, Kanyakumari, Tirunelveli, Tuticorin, Theni and the Palladam and Coimbatore belt. Tamil Nadu’s 2024 repowering policy, mandating repowering for turbines over twenty years old, makes condition assessment on ageing fleets there a live requirement rather than a discretionary one.

Karnataka. Chitradurga, Gadag, Koppal, Bagalkot and Davanagere.

Maharashtra. Satara, Sangli, Dhule, Nandurbar, Ahilyanagar and Osmanabad.

Rajasthan. Jaisalmer, Barmer, Jodhpur and Bikaner.

Andhra Pradesh, Telangana and Madhya Pradesh. Anantapur, Kurnool, Nandyal, and the Madhya Pradesh sites around Dewas, Ratlam and Sagar.

These eight states hold most of India’s wind capacity, and campaign economics favour clustering turbines rather than visiting single machines.

What we do not do

We do not inspect inside blades, nacelles or towers.

We do not carry out non-destructive testing of any kind.

We do not certify blade condition, structural integrity, remaining life or fitness for service.

We do not stop, start, park, lock or pitch turbines. That is the operator’s action by their own procedure.

We do not carry out repairs, coating work or blade maintenance.

We do not assess gearbox, generator, bearing or drivetrain condition.

We do not fly close to blades in conditions outside our wind limits, and we will lose a day rather than take a marginal pass.

We do not fly above the green zone ceiling without specific permission, and we do not fly in red zones.

Frequently asked questions

Does the turbine need to be stopped? Yes, parked and locked with the blades pitched, by your own personnel to your own procedure. The stop is measured in tens of minutes per turbine rather than the days rope access requires.

How many turbines can you do in a day? It depends on machine size, defect resolution required, wind conditions and how quickly the operator can cycle turbines in and out of stop. We quote turbines per day for your specific fleet and conditions rather than a general figure, and wind is the variable that moves it most.

What resolution do you achieve on the blade? Detecting small surface defects requires a ground sample distance at the blade surface in the region of half a millimetre to one millimetre per pixel. We state the achieved figure in every report, and we would encourage you to ask any provider for theirs, because a report without it cannot be judged.

Can you find cracks inside the blade? No. External imaging shows external evidence. Internal defects require crawler robots, internal access or NDT, and some serious blade defects begin internally with no external sign until late.

Can this support a life extension assessment? It provides the external condition data that feeds one. Under the MNRE 2023 policy, life extension refurbishment requires the turbine to be assessed and certified by a certification agency. We are not that agency. We supply structured condition data in a form the assessment can use.

Is it better than rope access? For finding and recording external condition across a fleet, yes, on speed, cost, downtime and safety. Rope access remains necessary for repair, for tap testing and for close physical examination of a finding. The sensible pattern is drone inspection to find and prioritise, rope or platform access to fix.

When should we schedule? The low-wind season, and within it the low-wind part of the day, so that downtime costs as little generation as possible. On most Indian sites that also means avoiding the monsoon, when flying conditions are poor anyway.

How often? Annual inspection is common on fleets where erosion is active, which in coastal and desert India is most of them. The between-campaign comparison, showing which findings progressed, is where a lot of the value sits.

Can you inspect after a lightning strike? Yes, and quickly. Strike damage and receptor condition are visible externally, and a dated record supports a warranty or insurance position.

Can you do our solar and our evacuation line on the same visit? Yes, on hybrid sites, and it is considerably cheaper than separate mobilisations.

Get a quote

Send us the turbine list with make, model, rating, hub height and commissioning date, the site location, and what you need: routine fleet inspection, a life extension condition assessment, post-event damage documentation or a site survey.

Tell us whether the site has solar or evacuation lines that could be covered in the same visit.

We will return the airspace position including whether hub height requires permission above the green zone ceiling, the turbines-per-day rate for your machines, the resolution we will achieve, and a fixed price for the campaign.