The incident occurred at the Screggagh wind farm in County Tyrone, which was developed by DW Consulting in 2011.
According to reports, the N80 2.5MW turbine's blades were "spinning out of control" prior to the collapse.
It received a large amount of attention in the UK press, possibly due to the quiet news period at the start of the year.
A Nordex spokesman said it believed it had uncovered the cause and was confident the collapse was a "one-off". However, he was unable to reveal further details. He also said DNV GL was conducting a separate investigation.
If the DNV GL finding correlates with Nordex's investigation, the project will come back online by Friday or Monday.