Originally Posted by
HeliComparator
meaning the design is not airworthy.
This is the right question; is the Servo Actuator design airworthy?
I hope that the attached attachments will also be useful for finding the possible root causes of the Bristow's Nigerian accidents.
Please note that the very sophisticated MSC.Software EASY5/Adams "NTSB Sikorsky S-76 Investigation, S-76 Flight Controls study and modelling has been made using the FDR Data from Copterline 103 accident despite as descript on the page 95, the first row "Loads were always set to the
reduced Sikorsky-provided condition for 80 % VNE (124 kts.). Copterline 103 accident speed was 93,5 % VNE (145 kts.).
It is very easy to understand the aerodynamical and load differences between the actual Copterline 103 speed and this Sikorsky-provided speed assumption for the NTSB simulation results?
The other NTSB EASY5/Adams test report with the 93,5 % VNE will extend the collective max up position about one second and the Sikorsky-provided 80 % VNE will extend the collective max up position within 3,5 second.
The FDR Data between Copterline 103 and Bristow 12th August, 2015 its well matching. Maybe the real root cause of the Copterline 103 accident was a separated Control tube from the Rod End?