AB139Eng.
I understand your scepticism but as previously mentioned by TET, the CFI on board at the time is very experienced and very respected. He didn't get the experience or the respect by doing things poorly. This incident happened on a check ride so the CFI would have been all eyes & check-lists.
It is possible that something was missed during the daily/preflight, but given the professionalism of the CFI and the circumstances of the flight I think it is highly unlikely. Also, the machine had just come out of maintenance so the engineers would have had to miss the signs as well. With so many people (CFI, Student and Engineers) looking, it would be unusual for "nobody" to see anything.
My info is that the aircraft had -4 blades fitted.....significant????
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