Thanks for those two posts Ericferret and Outhouse as they sum up the deficiencies in this matter. Neither of you will be pilloried by me. The mechanical outcome of the transmission failure in this case is almost identical to the outcome on Chinook FC. The AAIB have already reported on that and made recommendations to stop a recurrence. But a loss of rotor head has occurred again with the loss of all on board. There are at least too problems here, the failure of the gearbox and the resultant failure of the rotor head and control of the A/C. The latter should not follow the failure of the former and must be engineered out. I appreciate that in this case it was inevitable. (It must have been considered at the design stage and as nothing was done must have been ignored) Yes pilots must know what is going on in their gearboxes, yes engineers must have the tools to predict failure before it occurs and yes pilots should be able to autorotate following a transmission failure. A lot of work will need to follow and a lot of money spent to remove this risk from helicopter travel, we now know what happened, we now need to get after it. What caused it to happen I leave to the AAIB, but their findings and recommendations must eliminate a recurrence. ( and please do not use the word "ensure" in your recommendations as it is not sufficiently specific, please tell us exactly what needs to be done.) Radical re-design? Yes if that is what it takes. Would this known fatal failure mechanism be allowed to persist in any any other industry? No!