Originally Posted by
TwinHueyMan
I for one think that a lot of the basis of flight testing for the 206L blades may have been based on the 206B blades, on account of the sharing of the type certificate. Given the difference in transmission mounting systems and that VH said (in their blog post) that it was a harmonic interaction between the MRBs and the Nodal Beams, one can assume there was inadequate testing before release and up until now they’ve been doing what they can to minimize the issue to avoid a recall. Blaming Collective Bounce offloads the responsibility to a known boogeyman just as Bell did with LTE for decades.
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Agreed.
As stated before I'm not an "engineer" in the true sense as I don't have a degree.
Saying that my technical opinion is that the harmonics and feedback of VHA blades into the 206L Nodamatic system is an issue.
Bell tuned the Nodamatic system to suit the characteristics of their own OEM blades not for VHA blades manufactured under a PMA/STC.
This tuning is not adjustable.
I'm also curious why EASA won't approve VHA Main Rotor Blades.?
Whatever the cause of this horrific incident , I belive some additional attention needs to be paid to the operational and technical aspects of VHA MRB's on 206L series.
Time will bring the facts out I guess.
Edit.
EASA did not certify 206B Main Rotor Blades. Seems VHA did not pursue certification of 206L Main Rotor Blades with EASA.