GE Renewable Energy said it is treating the collapse of two of its machines within months as “separate and isolated incidents”, as latest research on the issue seen by Recharge says the wind industry needs a better understanding of the complex interaction of factors that can bring turbines down.

A GE 2.4-107 turbine crumpled to the ground at the Chisholm View 2 wind farm in Oklahoma last week, prompting the launch of an investigation at the project, which entered service in 2016.

That collapse followed a similar incident in February that saw a GE 2.5-127 fall at the Casa Mesa Wind Energy Center in eastern New Mexico, which only entered commercial operation in the fourth quarter of last year.

A spokesman for GE Renewable Energy told Recharge: “While we are still working through the investigation in partnership with the [Chisholm View] wind farm operator, we believe these to be separate and isolated incidents.”

In the case of the New Mexico collapse, “we have satisfactorily completed our investigation of the Casa Mesa turbine collapse in partnership with the windfarm operator, and are taking appropriate action,” said the GE spokesman, without giving further details.

“The quality and safety of our turbines is always of the utmost importance to us, and we have been communicating with our customers as appropriate.”

A spokesman for Chisholm View 2 project operator Enel Green Power told Recharge: "The investigation is still ongoing and to ensure the safety of the local community, we continue to ask the community to avoid the area of the incident at this time.”

Local media accounts of both collapses reported strong winds in the vicinities. Nobody was injured after either collapse.

As the probe into the Oklahoma incident continues, latest research into turbine collapses seen by Recharge highlights the range of factors that can cause them – often acting together.

“Most failure incidents of wind turbine towers are due to a combination of factors, among which extreme wind is identified as the most common,” says a detailed study of 48 tower collapses between 2000 and 2016 soon to be published by academics from the engineering department at the University of Birmingham in the UK, including professor Charalampos Baniotopoulos, chair of Sustainable Energy Systems there.

“Blade failure, fire, bolt failure or fatigue,” are also identified as secondary factors in the research, Wind turbine tower collapse cases: a historical overview. The researchers noted: “Tower failure tends to occur in the early-life stage, and is also called infant failure. This mostly relates to faulty construction, material defects and defective design.”

Human error, in areas such as quality control and construction have also played a role in tower collapses, the Birmingham team believes.

“The outcome of the present study should lead to particular reflections by stakeholders,” they said.

The study recommends the industry does more work to understand how the “multi-factorial” incidents seen in previous collapse cases are shaped by the “chain of design, manufacturing, construction, operation and maintenance”.