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Endurance E-Series Fixes & Upgrades

I’m conscious some clients are being targeted with information promoting several upgrades for the E series turbines.

To avoid unnecessary confusion we should explain Earthmill Maintenance’s position on the information you may have received. As we are turbine owners ourselves, we too will have to pay to have these upgrades completed. We therefore understand the importance of making the right decisions to ensure the longevity of our turbines.

As such, we have taken the time to evaluate ALL the various solutions being offered in order to give our clients (and ourselves) an independent view on what if anything is best suited to each particular site and situation.

Because Earthmill are not manufacturing any of the proposed upgrades we can offer a balanced view. If you would like to talk to us about this, please give the office a call. 01937 581011

Bed Plate Fixes

In some of the older turbines in Endurance the E-3120 fleet there has been instances of cracking in the bedplate of the nacelle due to fatigue.

Out of our fleet of 250 turbines, to date there has only been 1 failure requiring a complete new bedplate. Some high wind-speed and turbulent sites have however developed cracks requiring attention.

Earthmill Maintenance and Natural Generation have been working with an engineering company that specialise in welding repairs and have developed a robust process to strengthen the original bedplate to prevent further cracking.

The process is relatively inexpensive in comparison to complete new bedplate and does not require the nacelle to be removed. To date we have performed 80 of these repairs and have had zero repeat failures.

It is our belief that that this process would be sufficient as a preventative measure for the majority of Earthmill installed sites. However for more exposed and turbulent sites, a new bedplate may be the long term solution.


Replacement Bed Plates

There are currently three companies offering solutions for replacement bed plates. We have visited all three of these companies in order to evaluate which offer the best quality and value for our clients.

The planned solutions are all currently under final life cycle testing. We will update all our clients soon after a final decision has been made.



Expander pins

Prior to the unfortunate news of the bankruptcy of Endurance Wind Power there was a very important upgrade which Endurance had planned to offer throughout the fleet of E3120 wind turbines.

This important upgrade is to change how the blade is connected to the turbine. The existing blade guide pin was fitted during the installation of your turbine. It’s a simple bolt which allows the blades to move laterally on the hub and pitch when required in excessively high winds and overspeed conditions. Over time the existing blade guide pins have started to wear the guide holes on the hub, increasing in size and elongation. This excessive wear has a number of detrimental side effects to the operation and maintenance costs of the turbine.

  1. Premature Rod Tie Failure

The tie rods are designed to support the blades pitching if there is an over speed situation. Increased wear in the blade guide pins adds stress to the tie rods through shock loads which we think
is an important factor in the premature failure of existing tie rods.

  1. Reduced efficiency and turbine generation

Even a small amount of wear means the blades are no longer held in their optimum position and angle of pitch, which in turn results in a gradual deterioration of the turbines performance and production figures. Case studies at Endurance test sites looked at power curves before and after the upgrade. The results produced improvements in generation across the whole power curve estimated at a 5% increase to annual energy production (depending on the wear level of wear of the original hub).


Insurance backed warranties

by Matthew Dowley


  • Other factors to consider

There are other issues associated to the pin movement, such as possible noise complaints, spring failure within the blade which ultimately shears off resulting in blade failure.


The costs for the upgrade work will be between £3,500 and £5,500 + VAT per turbine depending on the level of wear and size of the elongation. The procedure for the upgrade varies depending on the condition of the existing blade assembly and blade type.

Earthmill engineers have all been trained in the installation process and we have purchased the specialist tooling required to ream out the worn guide holes in situ without removing the nacelle.

Personally I think this is a very important solution to a growing issue. As you know we own and operate a number of E-Series turbines ourselves and the obvious question is what do we plan to do? We will be scheduling in all of our own E-Series fleet to have the new pins installed over the coming months.

The solution has been designed to last for the full life of the turbine apart from the bushes; which are wearing parts and will be inspected within the normal service schedule. The manufacturer of the ‘expander’ pin warranties the pin for 10 years.


Shaft Upgrades

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X-Series Gearbox Failure

We have recently witnessed a small number of gearbox failures in our X-Series fleet.  We are working with a number of gearbox specialists to determine the cause of failure and to develop a fix. At present it is unclear if the issue is an inherent design failure that applies to the entire fleet or if the failures are isolated cases. Our X-Series clients will be kept informed as soon as we have further information. 

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