Originally Posted by
Hot and Hi
I do not know whether those blades damaged in 2013 were repaired or replaced. Or whether the damaged blades, alternatively the replacement blades, were already Dash-7 blades. Possibly the Dash-7 blades were fitted to ZK-IPY only at a later stage. As far as I know, the Dash-7 blades only came out in 2013, but I am not sure.
The accident report is out now. Although not yet listed on the CAA website, it can be found on the website of the Transport Accident Investigation Commission
skins/taicAviation/skin_aviation]Aviation Reports.
It is confirmed that the mishap helicopter at the time of the accident was equipped with the latest Dash-7 main rotor blades. Both blades fractured, but it was determined that this was due to overload, not fatigue:
Both main rotor blades had fractured [...]. Because the fracture of the red blade was near the point where another R44 blade had failed, which the CAA suspected had been due to fatigue, the Commission had this blade examined by a metallurgist at the earliest opportunity. The metallurgist’s initial assessment was that the blade had failed in overload. Subsequent detailed examination by the same laboratory and a further examination by an ATSB metallurgist confirmed this. The ATSB also determined that the failure of the blue blade was also the result of overload and not fatigue. Both blades were examined for signs of any pre-existing delamination or dis-bonding, and none was found.
Else, the cause was found to be mast-bumping followed by in-flight break-up, which occurred on a presumed straight and level flight at IAS of 100 KTS or higher, with no evidence of strong turbulence. It was presumed that the student was at the controls when the accident happened.