Sunday, 5 March 2023

Let‘s go

What if ??!?

Let’s go Odenwald! With a good friend on the set. Just let’s do it, he said …
(im Bild: Uwe Scherbaum,

Ohhh, im Ernst!!?!

Friday, 18 December 2015

Martin Grabert our expert down under

Dr. Martin Grabert, Brisbane, Australia, now supports HMS Experts & Classification Society (HMS Sachverständige Berlin e.V.) down under. As a student of astronautics and aeronautics he was one of the first coworkers in the first Aircraft Design Company of West-Berlin, the innovative enterprise carrying the letters HMS in its corporate name, dedicated to develop a High Performance Powered Glider Airplane. I proudly present his cumulated professional experience in research support and collaboration activities.

Friday, 22 May 2015

Production related weakness - how do you rate it?

HMS Experts in composite production technology Dr. Mertins and Dr. Holstein evaluating alignment of spar caps congruency to web suspension. What if waves and wrinkles weakens carbon girders? Can asymmetric load case trigger buckling? What if bonding lines of substructure between web and shell and of course at leading and trailing edge is of suboptimal adhesive performance? Can we trust flatback smooth curvature of LE UD reinforcement. Are international varying work behavior and cultural work related disciplin have influence on average blade production quality?

Sunday, 1 February 2015

Non-OEM Major Blade Repairs

D-Check of two V44 blades

Wind turbine blade damages spread in terms of its severeness from a cosmetic minor to a major structural relevant level. Not often such fatal damages are beyond profitable reconstruction cost estimates. Original Equipment Manufacturer (OEM) usually play that game with joy selling supposed total losses to insurance companies who are regularly unable to cope. 

HMS "the expert's voice" networks intends to escort blade owners in order to perform major overhaul (heavy maintenance visit) such blade patients without OEM support but nevertheless show long-lasting service life. Independance is our credo enabling potential blade service companies in order to provide e.g. high level carbon fiber repair technology and/or LPS reconstruction. Customers position such turns out to be the winner of unproductive stand-off situation at the end of the day.

It is our focus to handle catastrophic damages, make classification of damage level and design repair measures. We make safe that repair concept, workmanship and performance of repair execution is provided within requested ambitious level. Such we approve the repair trough the power of 20 years independent experts experience and keep an eye on conformity and formal approval referring to certification standards.

Sunday, 10 August 2014

Thursday, 3 April 2014

It is rare, but never the less it is true

Just one year old - not having seen extreme conditions when it happend. Some claim, it is a joke of April 1st, I doubt it.

It looks more likely someone has pushed the over speed button too long...

Sunday, 16 March 2014

Wellcome on board, Harald Schwarze, Varnish Expert first grade!

Harald Schwarze

HMS Sachverständige Berlin has strengthened its polymer wing of experienced old stagers. Harry has made his carreer all the way through from handicraftsman to member of the board of one of the leading Switzerland based paint manufacturers. He has accumulated profund experience in surface treatment in railways industries and gear box internal painting technology. The actual challenge in production supervision for off-shore rotorblades does entice Harry to break in on his hobbys like wave surfing and jazz drumming.

Wednesday, 18 September 2013

Living blade experience

"Old fox meeting"

Wolfgang, Ove and Stefan (from left) have in sum more than 50 years of rotor blade experience! I am very grateful for such face-to-face encounter and is one of curiosity of life.

Saturday, 16 March 2013

Personal Safety Training (Epoxy and Isocyanates)

Esbjerg, Dk, March 14 and 15, 2013
Most of the guys joining the classroom at AMU-Vest are pretty much familiar with the subject. In order to fulfill the regulations on the education program laid down by Danish law they all surrendered and so they were patient and hold out 2 full days. The "UDDANNELSESBEVIS CERTIFIKAT" was given for remuneration.

Tuesday, 5 March 2013

Siemens blade production accessible via Internet

Siemens Wind Turbines are presented in a high level show case here

Friday, 21 December 2012

It was my pleasure

Twentyeight years after this photo was taken, when the first wind turbine made by Ecotècnia was erected, where you can see (from left to right upright)
Josep Congost, Quim Corominas, Pep Prats, Pere Escorsa, Antoni Martínez, Ermen Llovet,
(and on their knees) Josep Puig, Miquel Cabré, Pere Viladomiu i Xavier Traver
Pep Prats and Miquel Cabré invited me to talk about blade strategy together with Richard A. Schmidt, Patricia Canalis, Alexis de Beaumont and Luca Feigl at Alstom Wind in Barcelona, Spain.
This is very honorfull for me, thank you.

Tuesday, 27 November 2012

Reliability and Failure Analysis of Wind Power Plants

The international conference "Failure and Damage Analysis" is addressed to manufacturer of wind turbines, suppliers, service provider of operation and maintenance, energy provider, wind farm operator, consulting engineers, technical experts, financial institutions and insurances from all over the world.
Two days in March '13, on 20th and 21st, read more about the program here

Saturday, 22 September 2012

Next Generation Unmanned Airborne Vehicles

Cassidian is the defence and security division of the EADS group and a major provider of global security solutions, lead system integration and aerial, land, naval and joint systems. Next generation of airborne military UAV or drones made me fall into evil mood. Visiting the ILA Berlin Air Show 2012 I had first time a feeling like being an engineer in astronautics and aeronautics is an embarrassment.

Never the less, civil use is measurable and we offer our expertise for damage analysis and root cause accessment for claim regulation purposes.

Monday, 18 June 2012

After Sales Service Conference Frankfurt am Main

December 4th and 5th 2012 the 3rd German After Sales Service Conference supported amongst others by Bombardier Transportation, Lufthansa Technik, Bosch and MAN is held to learn from experience of others. Dr. Holstein's contribution is to give an insight in wind branch business processes and lessons learned with respect to off-shore restrictions.

Sunday, 6 May 2012

Larger Rotors for low wind sites

Rune Schytt-Nielsen and Flemming Sörensen, Cofounders of SSP
"There is a strong trend towards larger rotors development in order to increase energy production and therefore decrease cost of energy production", Steen Broust Nielsen said when introducing today's challenges in blade design at the SSP site event on EWEA 2012 in Copenhagen. In the same time blade industrie will face an enormous price pressure due to very competetive environment in Asia Pacific.
Reliability concerns with longer blades will put an emphasis on suppliers and after sales service providers with clean records.
We at HMS feel very closed up to the SSP philosophy and have a similar approach to support the provision of blade quality through communication of approved service procedures, staff qualification and independant supervising services.
Feel free to get in touch with HMS Expert's Office, Berlin,

Sunday, 4 March 2012

Damage class four incident (see also rotor blade damage classes)

Rotor blade maintenance and repair standards are to be correlated to structual blade condition and for repair decisions on basis of damage classes. This posting shows without any doubt a damage class four finding (total loss).

In this case there is hypothesis for fatal blade failure mode by carbon UD-girder  fiber damage due to transverse force stress induced by glass fiber helix winding technique in order to fix the UD-stack in semi-automated beam production process. This issue is discussed in preparation of next Technical Advisory Board Meeting of the AK R (a committee of the German Wind Association, see also

Less severe damages like cracks or delaminations have virtually two dimensions. The first dimension visible at a first glance is what we call inspection findings. The second and comprehensive dimension of a damage can be assessed after removing layer by layer of affected material. It is the difference about damage amount and it's range.

Thursday, 16 February 2012

Interactive Knowledge Base on NDE of composites

In our every day analysis of failure modes and naming the root causes we recommend to standardize also well defined descriptions and in that sense definitions. Using the right classification for damage classes is one thing we often mention but also choosing the proper expression or definition for irregularities or findings is the other. We recommend the interactive knowledge base at netcomposites website. Http://
You will find 19 different failure modes of FRP material like "delamination" or "debonding" or "crack" and I find it very helpful.

Saturday, 24 December 2011

Rotor Blade Quality Surveillance requested

Blade quality surveillance (BQS) is one of strongly requested support issues. BQS concept of an Offshore wind farm comprises a complete third party assessment of each key procedure to obtain Type and Project Certificate. It covers design assessment (second phase), blade testing and surveillance of important steps in project (IPE). In order to obtain and retain blade airworthiness periodic monitoring of blade production, witnessing of quality assurance inspections, testing and supervision of whole life cycle operation is mandatory as well as supervision of maintenance and repair acceptance procedures.

Tuesday, 29 November 2011

HMS Technical Advisers strengthened

We proudly present MATTHIAS VYSHNEVSKYY joining the team. Welcome on board! Matthias has years of experience in flight physics as well as design approval and he is reinforcing the AVIATION wing of the HMS consultancy portfolio.

Wednesday, 10 August 2011

Lightning strike event scale

We talk about MINOR COSMETIC findings due to LS when only receptors and blade surface in some way swept over by lightning current. In those cases even receptors do not have to be substituted.
A bit more impact is performing the category WEAR OF COMPONENT, where receptors, connections and sparc gap are affected.
If you might find DAMAGE TO COMPONENTS, you have to admit that not only wear of structural integrity had happend, but also overload in critical sectors. You can have reasonable suspicion that lightning protection system is somehow a wrong design.
Incident with BREAK DOWN OF SYSTEM: in this category the component, i.e. blade is desintegrated and has to be replaced or repaired comprehensively.
And if there had been DAMAGE TO OTHER SYSTEMS you might talk about an accident with wider consequences.
(Event scale stated by Thomas H. Krogh, Electricon, Herning, DK)