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Old 24th Jul 2019, 13:23
  #420 (permalink)  
CTR
 
Join Date: Oct 2007
Location: Texas
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So Which Story is Correct?

Did the S-97 rotors mesh in the air as described in the NTSB report based on the analysis of the video? Or has Rotor & Wing misquoted the pilots description of events by writing that the rotors meshed as a result of the hard landing?

From Rotor &Wing Article:
A glitch in the code caused the flight control system to miscue during the transition from takeoff to forward flight, and the aircraft began to wobble as the computer lost control of the separation between the counter-spinning rotors. The aircraft responded to pilot inputs more powerfully than it should have, causing the aircraft to slam into the ground. The force of the impact flexed the rotors enough that they made contact and shattered, Fell (Sikorsky Senior Test Pilot Bill Fell) explained.

From NTSB Accident Report:
3.0 VIDEO SUMMARY. Video of the accident sequence of events was reviewed. The video was filmed from the right rear quadrant of the helicopter. It showed the helicopter slowly taxing forward with all 3 landing gear wheels in contact with the ground. As the helicopter approaches the edge of the runway, the tail wheel lifts off the ground followed by the main landing gear lifting off the taxiway simultaneously. As the helicopter gets airborne, the nose pitched upward slightly with a slight right roll. The helicopter then rolls to the left about 20° angle of bank and the left landing gear contacts the ground. A right roll followed that went slightly past horizontal. The roll reversed to the left, exceeding 30° angle of bank, then reversed to the right, and as the helicopter rolled through the vertical plane, the upper and lower rotors intermeshed about the 1 o’clock position (as viewed from the cockpit), creating a cloud of blade fragments and gray dust. The right roll continued, exceeding 60° angle of bank, then reversed to the left, and then landed hard as the helicopter passed through the vertical plane. The rotors continued to turn, decelerating until they come to a stop 43 seconds later.

Last edited by T28B; 24th Jul 2019 at 13:57. Reason: formatting of degree symbol
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