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Old 31st Mar 2022, 15:32
  #40 (permalink)  
lelebebbel
 
Join Date: Sep 2007
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Originally Posted by Reely340
I fly only S300C so pls forgive my lack of Robbie knowledge, but I am curious about that hair-rising flight state mentioned above.
I'd guess : fast yaw to the left due to lack of torque to counter and increased decay of RNR caused by diverting the remaining rotational inertia of the MR to the tail rotor.

Hence: immediate spatial disorientation combined with RNR needle dropping fast, correct?
Hard left yaw, combined with a strong right roll. I'm not going to make an attempt and estimate the roll angle, as i think those estimates are usually far off the mark, and i certainly didn't have time to look at an AI. The rotor decay was instant and likely caused by the disk being tilted forward into the air flow, due to the yaw and roll. I don't have good recollection of the recovery from the first time this happened, but the second time is still in my memory. The correct cyclic and pedal inputs to recover attitude were instinctive, so there was no confusion about the attitude we were in. Basically, full right pedal followed by lots of aft cyclic to recover the revs. Which in itself is not very effective because the extreme yaw really drops air speed, i think i had between 30-40kias left once straightened out. I also still remember the sound of the engine almost choking as i rolled the throttle all the way to the stop, and watched the needles labouring from horizontal back towards their normal position despite the collective being flat on the floor.

​​​​​​If i were to speculate, i think this scenario is one of many possible causes for this accident, but obviously there is no proof one way or the other so far.

Edited to emphasize, one of many possible causes.

For those instructing in these machines currently, you must guard the right pedal to prevent a student from shoving the left one forward. Unfortunately this is difficult to do effectively against a motivated student, especially considering all the other stuff you have to be ready for at the same time. In both cases, the autorotation was not a surprise throttle cut. The students also had done many dozens of autorotations prior, and were preparing for their commercial flight tests. Neither was a fixed wing pilot.

Last edited by lelebebbel; 31st Mar 2022 at 15:47.
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