Non destructive testing of blades before installation

Again questions arise if there is a way to test blades before installation or even after mounting with ultrasonics and/or infrared technology in order to quantify quality level or invisible or masked failures.

NDT techniques like the mentioned (US and IR) today (and I think for a long time in future) are not made to be used as a method for inspection of blades before installation in farms under construction. Both techniques have to be selected and adapted for the case of inspection one intends to do. IR has good features if you search for defects close to the surface. US have better potential if you want to look into the deep layers of structure. But non of these techniques can be used from root section to tip without dramatic change of parameters and system devices and measuring methods like frequencies, coupling heads, calibration and software setup. In other words: if you already know what kind of local fixed defect you are searching for and you already have tested and evaluated all these parameters for this case of testing, you have a slightly chance to be successful to find what you search for.

NDT like US and IR is not an all-purpose inspection feature and are to be chosen for very special assessment of blade defects. A day to day holistic blade quality inspection (inside and outside) like we do in many cases before installation is based on knowledge of the specific production process of the series production, the experience of noticed problems with this type of blade and the intuition of an old fox in the field of polymer chemistry, structural principles of blade design, aerodynamics, mass-dynamics of lightweight structures and last but not least independent standing of experts reference.

If you believe NDT blade testing is ready and in place for an universal monitoring of blade quality you may have been trapped by pseudo-scientific stories about fantastic new imaging techniques which is fiction for sure.

You ask for more information about the book project: tell the story of a case

First of all I would like to thank you all for your openness to contribute in one or the other way. I would very much appreciate if you could manage to describe a case where your technique or the concept you promoted was successful. This might be, for example, NDT in detecting rotor blade defects. There is some fascinating experience I know of, where ultrasound specialists have scanned sandwich sections with balsa core material where glass fibre layers were partially cut in some inexpressible stupid production process steps. If you don’t mind and if you are able to tell this story without embarrassing the involved parties, this way of illumination of the manuscript has my preference. That long winding canticle your competitors offer talking of putative ingenious equipment is boring to me. My intention is to act on fact boiling down the stories of this book.

I have some other "stories", or let us say "cases" in mind:
-> the peril of what we call greased lightning or
-> the putative efficiency of the 24 hours production cycle or
-> total blade quality through cascading qualified subsystem elements like embedded inserts, pultruded or prelaminated and consolidated structural sections and others.

What about your "story"? No wrinkles, collapsed flanges, tumbling webs ...
How do you feel about active load controlled single pitched blades?
What is the first thing you blade-brained guys have in mind if you go for 10 Megawatt machines?

Anyway - deadline of this call for contribution is coming up soon and I will get back to you offering a conference call for authors of the short list.

Take care - we do.

Call for Contribution

Work title of book project:
Turning wind into power
- State of the art of blade technology -
Dr. Wolfgang Holstein, Editor

I have plans to publish a specific white book about relevant blade related technology, as is

Non destructive testing
Condition monitoring
Lightning protection
Structural concepts
Material challenges
Automation of production process

I would be happy if you could distribute this call for papers to your colleagues who might have potential to contribute. Full size versions (not more than 12 pages) are expected in early summer 2010.
Do not hesitate to drop me a call if questions arise.

airborne inspections available

Encounter of my debut flight apparatus and its derelict

My personal flight career started on the rear seat of a C 172 with tail index D ELSE. This aircraft was owned by the Technical University of Berlin, astronautics and aeronautics branch, institute guidance and control and me at that time in the main study period to graduate for my engineer degree.
Its last mission was to deliver sky divers at my club at EDVH, the place out of which I operate my Airborne Blade Inspections.
Ashes to ashes and dust to dust.

About Oysters and Blades

If you want to check (without risk of poisoning yourself) the quality of an oyster, go for a cat and let her taste it –

– if she eats the oyster, it was good.

If you want to check (without any risk of observation faults) the quality of a rotor blade, go for an overload case –

– if the blade fails above the safe load value, then and only then you are sure, it was a good blade.

(old man’ saying with long beard, probably Professor emeritus)

I had a dream last night

And it does not seem that everything is all right. Long and winding roads were leading to this land of change where the wind was driving huge blades onshore and even more gigantic ones way out on sea providing turbines at its best. One can believe it is well done for our children and we always knew we should do it in the right way and this means to invest as much as we can to get off this oil and gas consuming way of life. Our personal capacity to invest is restricted. We invested our heart and brain and the wisdom grown was swallowed by affiliated groups of global players. So my dream ended with an apparent suicidal drop off the nacelle of a wind turbine. What I found this morning is that b.a.s.e. jumping is more naive and narcissistic than suicidal. Watch them jump, click here

What is essential to improve blade lifetime?

What is your opinion? How can we have best influence to improve blade lifetime?

:1: improve design?

:2: improve production technologies/quality management?

:3: improve maintenance and overhaul?

:4: improve terms of storage and transportation?

:5: improve inspection and blade accessment/on-site NDT method?

:6: improve meteorological prognosis?

:7: improve or develop realtime load measuring/managing and condition monitoring systems?

How do you feel we can improve - what is your experience? Do not hesitate to comment.

Frequently asked question about automatic blade inspections

These days I receive numerous mails and phone calls pointing out there is a new automatic blade inspection device available.

“Do you know this robotic system?” they ask. Yes, but …

From time to time you may find breaking news about putative brilliant inventions to solve the necessary blade inspections without the needs of a human inspector. Fantastic ideas are presented and spread out full-bodied across mainstream media. I don’t mind if this information is precise and do not keep quiet about the fact that this is based on academic style pipe dreams, chimeras to win project sponoring and not worth to deal with it. I even don’t mind the fact originators have to suffer in their upcoming insomnia which may develop to a full-grown nightmare when the truth was made public. It is for sure that top-ranking scientific institutes may suffer the loss of their reputation playing around like this.

Sorry, I don’t care.

who we are