The hard landing suffered by Sikorsky’s S-97 Raider in early August was caused by issues with the flight control software as the aircraft performed a vertical takeoff at the beginning of a flight test, Sikorsky has confirmed.
The findings were revealed as the National Transportation Safety Board (NTSB) published its preliminary report into the incident on Aug. 2, which significantly damaged the aircraft’s retractable landing gear, but caused no significant injuries to either of the two flight crew members on board.
In a conference call with media, Chris Van Buiten, vice president of Sikorsky Innovations, said Sikorsky was “fully committed to the program” and is moving forward on returning to flight with the Raider in 2018 as the investigation into the hard landing continues.
Van Buiten said the incident took place at the beginning of that day’s flight test at the Sikorsky Development Flight Center in West Palma Beach, Florida, after the aircraft had taxied to its takeoff position. He pointed to the “complex interaction between the ground, the landing gear, the flight control system, and the associated pilot interactions” as the fly-by-wire Raider transitioned from operations on the ground to operations in flight.
“In fly-by-wire helicopters, there are transitions in the flight controls that happen during the event, and in our analysis of the [hard landing], that transition didn’t go exactly as it should, and we’re making some changes to the flight control system software to accommodate that and ensure that it never happens again,” he said.
“We have been able to reproduce the event in our simulator and we are confident in operating with the NTSB to . . . get to the root cause and fully understand the issue.”
Van Buiten said the manufacturer had done a “deep dive” into all its fly-by-wire aircraft programs — which include the CH-53K King Stallion and CH-148 Cyclone — and found the software feature that caused the hard landing does not exist on those platforms. (end of excerpt)
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