EC225 crash near Bergen, Norway April 2016

[Skotty]

Mitchaa @ #825

I agree with Kawijet @ #822

The following quote from the AAIB report on G-REDL confirms that the top part of the MGB detached along with MRH:

"The upper section of the gearbox assembly, which included the remains of the second stage of the epicyclic reduction gearbox, the conical housing and all three lift struts, had detached from the MGB and were recovered with the rotor head."

I have attached the drawing of the MRH (main rotor head) to which I have added pointers. LN-OJF's MRH separated at the joint between the lift housing and the flared housing. This is the same joint which would be separated when removing the MRH from the MGB (main gearbox) during maintenance. G-REDL's MRH separated at the epicyclic casing which is below the flared housing. This was due to the rupturing of the epicyclic casing.

We will just have to wait for the official report on why LN-OJF's MRH separated from the MGB at this point, but in my opinion this would be the most likely spot for the separation to occur if the lift forces were routed through the MGB casing instead of the struts. Of course this is just one out of many scenarios as to why it separated here.