Old 9th Nov 2018, 19:03
  #725 (permalink)  
Chronus
 
Join Date: Jan 2008
Location: Hotel Sheets, Downtown Plunketville
Age: 72
Posts: 687
Originally Posted by arizona View Post
As a former helicopter pilot I experienced three total engine failures in single engine helicopters and three lucky autorotations that saved the day for my pax, me and the company. Most of my helicopter time though is logged in twin engine helicopters, one of which also gave me an engine failure, but that was in level flight and therefore nothing of interest..

With Occam's razor in mind I got to my very own simplified conclusion that this accident started with a tail rotor failure that turned out catastrophic due to no visual recovery in the blurry video. The helicopter’s counter rotation and the engine sound made me think the helicopter descended with high power and high collective all the way to the ground.. The shape of the tail rotor blades on the downed helicopter made me also think that the helicopter hit the ground with the TR not spinning at all due to a TR drive failure… Why wasn’t the pilots able to lower the collective?


My guess would be because it was a time critical event.
Factors are : Height above ground coupled with the likelihood of occurence at critical moment of transit to forward flight, size of helicopter, twin engines, high rotation speed following TRFand location of site.
Any chance of succesful recovery would have entailed almost instant recognition of TRF, immediate power reduction and simultaneous pitch down for immediate descent and autorotation, which would involve a high ROD and require favourable terrain below. Might be survivable at low height but not so at the sort of height involved in this instance.
I would readily admit I know little about rotary wing, but I understand that they are far less forgiving than their fixed wing sisters. One thing in common must be that with the vertical stab gone on a fixed wing it also spells curtain time, but as in the cases of the JAL123 747 which managed slightly better than AA 587 they seem to keep going for a little longer before the inevitable. With rotary wing the equivalent of no TR means in no time at all the machine assumes the characteristics of a dandelion strung to a brick.
I really don`t think even the most accomplished pilot could have pulled it off. It would have been a far greater miracle than the Hudson one if they had, would be my humble view.
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