Wind turbine elevators: are we safe?

Brown windmill. Original public domain | Free Photo - rawpixel

All of us, old wind turbine grease monkeys, still remember it. It was the end of 2015 when we heard the news: in a wind farm in Germany, one technician died and another one received life lasting injuries when the elevator they were in, manufactured by Avanti (now Alimak) fell when its hoist system, manufactured by Tractel, failed, and its emergency arrest system, manufactured by the same company, did not stop the elevator’s fall as it was supposed to. We all remember the accident’s aftermath, with affected every wind turbine that had it installed and consequently, our lives in the wind farms throughout the globe.

After an initial period where their use was banned, waiting for the official investigation, in which it was determined that the issue was caused by a supposed tamper with the hoist’s torque limiter, and apparently lack of maintenance in the arrest system (which, to clarify, it was supposed to be “largely maintenance free”, as it was read in the manual version current at the time), Avanti released a note to all customers. My memory of that note coincides with what we can see in the image: in it, after explaining how the arrest system, named Blocstop, worked (brakes would be activated by the centrifugal force caused by any excess of speed over the designed working limits), Avanti moved to explain the “solution”: moving forward, a test was required prior to their use. In essence, to perform the test (which to my knowledge is still being done), the elevator needed to be raised one foot above the platform. Then, one technician had to go to the first platform above, in what is called the lower mid section of the structure, hold the cables that run in both the hoist and arrest system, and give a pull to the Blocstop’s wire rope. If the arrest system engaged, the elevator was safe to use. There were no changes made in any of the components, but there was a change in the maintenance to be performed: from being, as I explained, “largely maintenance free”, Avanti moved to a yearly maintenance… that had to be performed only by technicians qualified by Tractel. Guess who were those “qualified technicians”? You guessed right: only Avanti personal was authorized to do that. So, ironically, instead of being an issue, the accident became a business opportunity for Avanti, which even to these days, resulted in a HUGE source of income for them.

I must add that these arrest systems have a sight glass in their casing, that in the time prior to the accident, allowed the customers to see if the rubber rollers, the part of the system that performs the job of stopping the elevator in case of an overdrive by compressing the cable that sustain it, had excessive wear and therefore, required replacement. Or so we all thought…

Due to circumstances that are not the subject of this article, when I was working in my former company, I had the opportunity to investigate this system. During this investigation, I found a note in the Avanti’s webpage, of which you can see a portion in the second picture. Almost identical to the first one, except for a paragraph at its end. When I found it, a chill went through my spine. The paragraph read: “However, investigations has revealed that above guides can’t ensure condition and reliability of the rollers in a subsequent emergency where the Blocstop is intended to lock on the wire.”

Understand that the “above guides” refers to the test I mentioned before. Translated (and tell me if you understand it differently), Avanti said that the required test means nothing in a real situation. Which makes sense: one does not need to know too much physics to understand that the inertial forces at play are WAY different in a free fall, compared with a stationary elevator that is released a foot off the ground. Duh.

Avanti was asked about both notes. They negated the existence of the first one, stating that the second one was the only one released to the public. Smart move: with that, they transferred the responsibility to its customers, since they supposedly had knowledge of the fact. Unfortunately, my former company, with the attention to the detail that seems to be their motto (read this in a sarcastic way), could not find (or at least that is what I was told) the note sent to them at the time right after the accident. Therefore, until one of their customers finds the first note, Avanti is covered on this. But its costumers aren’t.

You may be thinking: “well, it seems that the problem was solved, since there haven’t been more accidents since, right?” WRONG. During my investigation, I found that, since the accident, my company have had NUMEROUS incidents where the elevator fell a few feet on its own, more than the Blocstop should allow them to. And it let me wondering how many more times it happened and was not reported, due to the infamous “normalization of deviance”. And another thought came to my mind: yes, there is a maintenance program performed every year, but a question arises: which tests they performed to know that a year is the right period? I mean, we all know how different their use can be from one turbine to another: some turbines run uninterruptedly in that period, while others may fail more often and require more visits. These elevators have a time counter: why not using them to determine if a change of the rollers is required sooner, since the sight glass is useless, as the rollers may be worn to a dangerous level that will not be captured with a visual inspection? Moreover, even the time counters are not a reliable method, since the stress to which they are subject in each trip is different, due to multiple factors, like wind speed, temperature or dusty environments (which I learnt from an Avanti technician that greatly affect these rollers).

Months ago, I reported the issue to OSHA. Surprisingly (as they are required by law to let me know the result of their investigation, whatever that may be), I haven’t heard from them yet. This is why, despite knowing that this may be the end of my career in wind (nobody likes a person who report issues to OSHA, however right he may be, isn’t it?), I decided to publish this article. If you read this, I hope that you do what you preach and take actions to ensure the safety of your employees. Me? I can care less about my future in this market; I care much more about the safety of the people who day in and day out risk their lives enough in an environment that is already dangerous enough.

If you have reach this point, thank you for paying attention. And please, do the right thing before one day this becomes more than a near miss.