NTSB Releases Factual Report From 2017 S-97 Raider Accident | Aero-News Network
Aero-News Network
RSS icon RSS feed
podcast icon MP3 podcast
Subscribe Aero-News e-mail Newsletter Subscribe

Airborne Unlimited -- Recent Daily Episodes

Episode Date

Airborne Unlimited-
Monday

Airborne-Unmanned w/AUVSI-
Tuesday

Airborne Unlimited-
Wednesday

AMA Drone Report-
Thursday

Airborne Unlimited-
Friday

Airborne On ANN

Airborne Unlimited--12.09.19

Airborne UnManned--12.10.19

Airborne Unlimited--12.11.19

AMA Drone Report--12.12.19

Airborne Unlimited--12.13.19

Airborne-YouTube

Airborne Unlimited--12.09.19

Airborne UnManned--12.10.19

Airborne Unlimited--12.11.19

AMA Drone Report--12.12.19

Airborne Unlimited--12.13.19

Fri, May 03, 2019

NTSB Releases Factual Report From 2017 S-97 Raider Accident

Aircraft Experienced A Hard Landing While Hovering At The William P Gwinn Airport (06FA) In Jupiter, FL

The NTSB has released a factual report from a hard landing which occurred August 2, 2017, at about 0720 EDT involving an experimental Sikorsky S-97A, N971SK, that was hovering at the William P Gwinn Airport (06FA) in Jupiter, FL.

The aircraft sustained substantial damage during the test flight, however both  airline transport-rated pilots sustained only minor injuries.

According to the report, the helicopter taxied to the runway hold short line for runway 9/27 at taxiway A (alpha), lifted into a low hover, and immediately experienced excessive roll oscillations which lead to intermeshing of the counter-rotating coaxial rotor system, and a hard landing. The flight crew shut down the helicopter, allowed the rotors to coast to a stop, and egressed the helicopter normally. Damage to the helicopter included collapsed landing gear, structural cabin damage, and dynamic component damage, including rotor blade tip separation of all 8 rotor blades.

The pilot-in-command told the NTSB he was in the right seat and manipulating the controls at the time of the accident. He stated that he applied collective to get the aircraft light on the wheels and then applied forward cyclic to initiate a roll forward (forward taxi). He ground taxied the aircraft to the runway just as he had done on other flights. He intended to hold short of the runway and wait to be notified that the SAR (search and rescue) aircraft was on station.

As the aircraft approached the runway, a slight left roll developed. The pilot decided to lift the helicopter into a 5-foot hover and stabilize. As he applied collective and got airborne the helicopter rolled quickly left and then right, continuing with 2-3 roll reversals of increasing roll attitudes eventually exceeding estimated 60 degrees angle of bank. The pilot applied counter roll control inputs, but roll rates experienced were excessive. After 2-3 roll reversals and after a large right angle of bank roll, as the helicopter reversed its roll, the pilot lowered the collective to full down to execute a landing.

After the landing, he shut the engine down, and completed the emergency shutdown procedure. He and the copilot egressed the helicopter normally.

The event occurred while taxiing on the runway with light weight on wheels, high collective pitch, and a slight forward cyclic pitch stick. Due to the light weight on wheels during the taxi, the flight control mode transitioned from ground mode to flight mode. The slight forward pitch stick in combination with flight mode initiated a nose down pitch rate.

The pilot took corrective action inputting aft cyclic stick to correct the nose down rate. The initial pitch axis correction led to a small initial left roll rate due to aircraft coupling. The pilot countered the small left roll rate with an appropriate magnitude right stick input. In conjunction with the right stick input, the pilot raised the collective to increase the altitude. The aircraft right roll response to the right stick input was larger than expected and the pilot countered with a large left stick input.

The aircraft left roll response was also larger than expected. The larger than expected roll response to the pilot roll stick input was the effect of a flight control system design error that resulted in unintended changes in the pilot input sensitivity in the roll axis during the transition from ground control mode to flight mode.

Sikorsky reported that the increased control sensitivity was never encountered in the initial piloted simulation evaluation, nor in the 15 subsequent aircraft flights after the flight control software revision was made. However, once the incident timeline was precisely determined, the increased sensitivity to pilot control input could be consistently replicated in the simulator.

(Image from NTSB report)

FMI: Full report

Advertisement

More News

Airborne 12.13.19: Snowbirds AirVenture-Bound, DeLand Showcase 2020, ePlane Flt

Also: First Modified Osprey, Sunken F4F Wildcat Found, Rebuilding Monmouth IL Airport, Boeing Fine The Canadian Forces Snowbirds will make AirVenture a part of its 50th year perfor>[...]

AMA Drone Report 12.12.19: A.I. Robotic Racing, Drones v Dogs, Dronestrike Claim

Also: Recreational Drone Flying Aeronautical Test, Drone Poll, OSU Drone Project, AF Academy UAS Center Lockheed Martin and The Drone Racing League have announced the winning Alpha>[...]

Airborne-Unmanned 12.10.19: EHang In-City Demo, ISO Standards, DroneStrike?

Also: Drone Aviation-ComSovereign, Public Safety UAS Training, Disaster Management, NCDOT Drone Program EHang has announced its strategic partnership with property developer Heli C>[...]

Aero-News: Quote of the Day (12.15.19)

“You can think of a PMA as an egg that’s a part of an entire carton—the STC is the entire carton, with regard to STCs. We can sell the entire carton, the STC, or >[...]

ANN's Daily Aero-Term (12.15.19): Digital-Automatic Terminal Information Service

Digital-Automatic Terminal Information Service (D-ATIS The service provides text messages to aircraft, airlines, and other users outside the standard reception range of conventiona>[...]

blog comments powered by Disqus



Advertisement

Advertisement

Podcasts

Advertisement

© 2007 - 2019 Web Development & Design by Pauli Systems, LC