In this episode of Weather Guard Lightning Tech‘s The Uptime Spotlight, our CTO, David King joins the conversation to dive into RootFusion—GWT’s innovative up-tower root bushing repair solution.
David breaks down how RootFusion is addressing one of the industry’s most persistent blade failure issues—making repairs more efficient, more cost-effective, and more reliable.
Key Topics:
The Problem: Root Bushing Defects: Blade root bushing failures weaken the connection between blade and pitch bearing, posing safety and cost risks. Early signs include dust on the gelcoat, visible gaps, or audible movement. These issues stem from fatigue, manufacturing variation, and long-term loading—and require consistent terminology and early detection to manage effectively.
The Solution: RootFusion Up-Tower Repair: GWT’s RootFusion allows damaged bushings to be repaired up tower—no cranes needed. A small crew uses a lightweight kit and specialized tooling to restore both chemical and mechanical bonds. The process takes 3–5 days per blade and includes pre- and post-repair UT scans to confirm quality.
Detection & Risk Management: Operators can spot early damage using simple checks like feeler or dial gauges. UT scans are ideal for confirming suspected issues. While fleet-wide scans are rarely justified, early action is key—unaddressed damage often spreads in mirrored patterns and can lead to full blade failure.
Scaling and Field Deployment: The repair process is kit-based, scalable, and now being delivered through trained field teams. Over 20 technicians have been certified through GWT’s New Orleans training center. The company also supports operators with factory audits, risk analysis, and inspection services to extend blade life and reduce operational risk.
Transcript
Allen:
Damaged blade root bushings cost operators millions and pose serious safety concerns across wind farms, making solutions that don’t require expensive cranes and downtime crucial for the industry. This week, we speak with David King, Chief Technology Officer at Gulf Wind Technology.
David’s team has developed a groundbreaking method for repairing damaged blade root bushings up tower—saving operators from costly blade replacements while extending turbine life and reliability.
Welcome to Uptime Spotlight, shining light on wind energy’s brightest innovators. This is the progress powering tomorrow.
[Music]
Allen:
David, welcome to the podcast again.
David King:
Yeah, thank you very much. Thanks for having me. It’s an exciting event that we’re here at, so really looking forward to this.
Joel:
There is so much happening at Gulf Wind at the minute. Just been watching some of your intellectual property pop out and some of the new things at this show—
All kinds of areas that you’re investing in in terms of blade repairs that have been needed for probably two or three years.
At this point, you have good solutions. The one I think we’re most interested to hear about is the blade root bushing or insert repair that happens up tower—because everybody’s asking about it.
Allen:
I think that’s the important thing—first off we need to get some common language around what this problem is.
Everybody’s calling it root bushings, root this, infusion that… what are we actually talking about here? How do you brand this exactly?
David King:
Yeah, just like you said, it’s really been a long time coming. It’s something we’ve been involved with for well over three years. We got introduced originally through an RCA—Root Cause Analysis.
When you do that, the first thing you need to do is establish the terms, create a common framework. With this particular issue, it often starts with how customers first become aware of the problem.
Some become aware through blade failure—blade on the ground. That’s the worst scenario. Others see dust on the gel coat, gapping at the blade root, or even visible daylight between the blade root and pitch bearing.
All of it points to loss of connection between the metal root bushing and the composite laminate. That causes the blade to loosen from the pitch bearing.
Allen:
So, where exactly in that assembly is the breakdown occurring? Is it where the bushing meets the composite? The composite itself? Or are we pulling on the studs too hard?
David King:
Great question. One fundamental thing is to separate damage from defect. The damage you’re seeing—the loosening effect—is happening because that metal bushing is losing its pre-tension.
It relies on a mechanical and chemical connection. There’s this sinewave-like geometry in the bushing that the composite wraps into—creating a compression joint.
Over time, that connection starts to break down. The composite in those grooves forms into dust and slowly slides out.
Allen:
Is there fiber inside those grooves? Or is it just resin?
David King:
The goal is always to get fiber in there. You need the right fiber-resin ratio to perform well. But the issue is compression strength depends on resin, which is the weakest part of a composite.
Joel:
So is what we’re seeing in the field due to bad manufacturing? Or is this wear and tear? Or materials?
David King:
Really good question. And the answer varies depending on blade type. That’s why we do RCAs. In our experience, it’s usually a mix—design complexity, manufacturing challenges, and maintenance.
You need creative solutions, but you also need to address each of those contributing factors.
Allen:
What’s the first sign an operator has this issue? Dust on the outside? Can they hear it as it spins?
David King:
Absolutely. You don’t want the first sign to be a blade on the ground. Dust buildup is a big one. Visible gapping is another—techs can check with feeler gauges.
You can sometimes hear the blade move—but that’s already mature damage. Ideally, you want to catch it earlier to avoid safety and performance risks.
Joel:
So let’s say an operator thinks one blade has this issue—do you go out and do NDT on the whole wind farm?
David King:
That depends on the operator’s business case. Some plan to repower in 2 years. Others want 20 years of life. So the solution varies.
We’ve seen everything from condition monitoring with acoustics, gap sensors, accelerometers—to UT testing (ultrasonic). UT is very useful pre- and post-repair, but not for scanning 300 blades unless you’ve already narrowed the risk.
Allen:
Do the worst bushings tend to be on the leading edge? Trailing edge?
David King:
It depends on the blade and whether it’s an older fatigue issue or a newer static one. We see damage over spars, corners, or between the leading edge and spar cap.
But there’s always a pattern—if you know what kind of blade you’re looking at.
Joel:
So if you know the blade model, you know which bushings are likely to fail?
David King:
Yes. We use UT tech that originated in aerospace. It gives us a fast, comprehensive way to scan the full blade root and identify risk.
Say you have 64 bushings—maybe 10 to 15 are bad. If you have 90, maybe 20. And they’re often mirrored left and right.
Allen:
That’s not as bad as I expected. I’ve heard some operators say they need to replace all inserts.
David King:
If you catch it early, you don’t need to. But if you wait, it gets progressive. Eventually every bushing can fail.
You get “unzipping” failures. And in extreme cases, we see gelcoat cracks at the blade root—through the first meter or so of the blade. That’s likely a scrap blade.
Joel:
Once cracking gets into the blade root, is there really a way to recover that?
David King:
Not cost-effectively. You could repair anything—but rebuilding a root is expensive. You need to assess the business case. Sometimes, you might justify a major down-tower rebuild, but that’s rare.
Allen:
Now let’s get into your solution. How are you fixing this up tower—without a crane?
David King:
We have a huge passion for composites at Gulf Wind. That’s our history—whether aerospace, auto, or wind.
When we got this problem, we knew the solution had to be up tower. No cranes. No taking blades down. We needed a 3- to 5-day repair with lightweight gear and minimal disruption.
So, we developed what’s essentially laparoscopic surgery. Small holes, minimal invasion. We don’t touch the healthy composite—only the damaged zone.
We send three techs up tower with a 25 lb kit, plus a 40 lb materials bag. They stay up tower for 3–5 days, target the right bushings (identified via UT), and perform a pressurized adhesive injection.
Joel:
What kind of pressure are we talking?
David King:
That’s a bit of the secret sauce. But it’s well beyond vacuum infusion. Think of it like a root canal—high pressure, precisely delivered.
We purge out contaminants—dust, oil—and inject a custom material that chemically bonds and mechanically fills the voids.
Allen:
So you’re restoring both mechanical and chemical integrity?
David King:
Exactly. The material we use is lab-tested—even mixes 1:1 with oil and still cures with strength. Once in place, we let it cure, then run post-repair UT to verify everything.
We’ve done 3-, 6-, and 12-month follow-ups—and seen zero issues.
Joel:
And this isn’t an unusual repair timeframe. I’ve seen 3–5 days spent on shear web repairs inside blades.
David King:
Exactly. Big shoutout to our process team. We’ve simplified composites. Created clear work instructions, minimized variables, and made this repair scalable.
Allen:
And now you’re training other crews?
David King:
Yes. We’ve trained 20 techs so far at our New Orleans center. This process is fully certifiable. Kit-based. Shippable. Executable globally.
We’re transitioning from internal crews to training third-party teams.
Joel:
Could you apply this method pre-installation to known problematic blade types?
David King:
In theory, yes—but most blades don’t show damage until post-install. Still, we’re seeing interest in due diligence: factory audits, pre-delivery inspections, and owner’s engineering reviews.
Allen:
You offer those inspections?
David King:
Absolutely. We’ve done them across many countries. It’s great for peace of mind, insurance, and financing.
But inspection must lead to better risk prediction. If not, it’s just cost without benefit.
Joel:
This technology’s going to be busy this summer—and beyond. Thousands of blades out there have this issue.
Allen:
So what’s next for Gulf Wind?
David King:
This root bushing fix is just the beginning. We’ve got exciting work in new composite manufacturing methods and performance engineering.
Especially for low-wind sites in the Southeast. Historically, wind’s been concentrated in the Midwest. But data centers and population growth are shifting demand to places like Mississippi and Louisiana.
We’re building tech to make wind viable in those low-speed markets.
Joel:
That’s critical for the future of U.S. wind.
Allen:
David, it’s always great to have you back on the podcast. We’ll come visit—just not in the New Orleans summer!
David King:
Absolutely. Thanks for having me.
[Music]
