Weather Guard Lightning Tech

IWTG Consulting on Pitch Bearing Cracks, Loose Root Inserts

Jon Zalar, founder of IWTG Consulting, joins to discuss broken blade bolts, cracked pitch bearings, loose root inserts, and early detection.

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Allen Hall: Jon, welcome back to the program.

Jon Zalar: Thanks for having me.

Allen Hall: Uh, last time I saw you, we were in Melbourne- Yep … at WOMA 2026, and that was a huge event. We know we’re gonna do it again next year in March three, the 3rd through the 5th, so you’re invited back, of course- I can’t wait … if you can make it. Yeah. Yeah.

It’s gonna be, it’s gonna be a good time. A lot is happening in the blade world and in the wind turbine world more broadly. A lot of things we’re hearing right now are related to blade bolt connection, pitch bearing inserts still. A lot of that still happening in the United States. What is the current status of, uh, the blade connection issues in the US?

Jon Zalar: I feel like it’s a growing [00:01:00] issue, not super, super fast, but it seems to be getting a little worse. There’s, you know, more bolts breaking at that joint. Um, pitch bearing cracks are, seem to be pretty common. There’s different solutions for it, and then, you know, the root inserts are another thing that we’ve talked about before that seem to be happening more and more, or maybe more and more people are finding them ’cause they’re looking.

Allen Hall: What are the first indications that you have a blade bolt or some sort of joint issue at the root of a blade? What can you see?

Jon Zalar: A bolt laying in the hub bouncing around. Um, you know, from like a– looking at it from, like, the sensors on the turbine, it’s really hard to tell unless it gets really bad. Uh, some of the OEMs have some analytics developed to kinda start to indicate if there is a aero change because there’s missing bolts or root inserts are coming out, and they’re using that as a way to go figure out which ones to go inspect first.

Allen Hall: Really? Yeah. You think [00:02:00] the SCADA data will give you some indication that you have a, basically a little bit of a loose blade?

Jon Zalar: Yeah. I, I, I think because the number of turbines and the number of data points you have, I think there is a pretty good analytic out there right now.

Allen Hall: Wow. All right. I think a lot of our operators have not taken advantage of that.

Is, is that just b- based on the high-speed data, SCADA data, or is it low-speed data you could see that same effect?

Jon Zalar: I believe it’s on the low-speed data as well, but I bet the high-speed data was used to kinda develop it.

Allen Hall: Wow. All right. So that’s a huge help to operators. Yeah. So what are you looking for if you’re looking through SCADA data, what would be the couple of markers there that say, “Hey, maybe we ought to go look up at the– in the hub”?

Jon Zalar: I don’t know exactly what they’re using, but they would basically look for maybe an imbalance or looking for certain components that are being overworked.

Allen Hall: Oh, sure. Okay.

Jon Zalar: Yeah.

Allen Hall: So your pitch actuator may be getting a little bit overworked. It would seem like one of the places- I think that, yeah … that would get loaded, right?

Jon Zalar: Mm-hmm.

Allen Hall: Okay. [00:03:00] And any vibration monitoring going on? Because it, it, uh, in some cases you’re– I’m hearing, like, millimeter gaps-

Jon Zalar: Correct. Yeah …

Allen Hall: between the blade and the pitch bearing.

Jon Zalar: So probably a combination of the ALC sensors, at least on a GE turbine, looking at that. But the PCH box also is looking at the tower vibration, so it could be a combination of all three.

I don’t know the exact- Okay … details, but between all of that, I think there are some analytics that kinda say, “Hey, go take a look.” And then I think there’s some other companies that have- tools that go monitor it.

Allen Hall: Mm-hmm.

Jon Zalar: Dial indicators remotely or even, you know, people going up there with dial indicators to go kind of rotate the rotor and kind of see if there is gapping between the blade and the pitch bearing.

Allen Hall: Is that a safe situation in your– from the gapping? I’ve heard this where they’ve basically took shims and they’re trying to measure this gap or some sort of dial indication. Is that a smart thing to do? Is it even reliable to do it that way? [00:04:00]

Jon Zalar: I, I, I think there’s some reliability there. And like, you know, these are really big parts, right?

So like a little bit of gap, it, it’s probably expected to a point, but growing gaps is where you should be a little more scared.

Allen Hall: So you’re– you would have to go do that quarterly, monthly, weekly? How, how often would you have to do it to see the progression? Because I’ve heard stories of, uh, a couple of weeks from nothing to hub crack to, “Oh, it took a year or more.”

Jon Zalar: I think it depends on the issue. I think for– if you’re looking at that, the bolted joint itself between the root inserts and the, uh, bolts breaking itself, I, I think they’re doing about quarterly. Now, the pitch bearings inspections are also quarterly. They’re al- they’re, they’re leveraging the drone inspections for the blades, and they’re looking at the pitch bearings to see if they’re cracked, right?

Uh, you guys are doing that too.

Allen Hall: Okay.

Jon Zalar: I think Coraly is doing a good job mitigating the risk, feels like.

Allen Hall: Wow. All right. [00:05:00] Yolanda, looking at pitch bearings, you’ve looked at a lot of drone images in your lifetime. Mm-hmm. How much can you see on drone images on pitch bearings? Can you see cracks and, or y- or do you see grease, which is ...