NTSB on LA A109S Rooftop Hospital Helipad Landing Accident (N109EX of Helinet Aviation Services / Prime Healthcare at USC Kerk)
The US National Transportation Safety Board (NTSB) have published their preliminary report on Leonardo Helicopters AW109S N109EX of Helinet Aviation Services which crashed onto the University of Southern California (USC) Keck Medical Center (USC Keck) rooftop helipad in Los Angeles, California on 6 November 2020.
The helicopter was making a Part 135 helicopter air ambulance flight, with a donor heart for a transplant operation aboard. The pilot suffered minor injuries and the two passengers were uninjured. The Los Angeles Fire Department (LAFD) retrieved the organ from the wreckage and the hospital says “the heart was successfully transplanted following the crash, and the transplant recipient is recovering well”.
The pilot reported that he established the helicopter in a steep approach, to land on the rooftop helipad of a multi-story medical building [approaching in a northerly direction over Hazard Park according to videos of the accident].
The pilot had offset his heading to the left to gain greater visibility to the landing zone. He observed the absence of any wind indication from the windsock and no movement on nearby trees. When the helicopter had decelerated to about 45 knots, he increased the engine and rotor RPM to 102%.
About 40 feet above the helipad, the pilot noticed a slight yaw to the right that continued despite full left pedal application. He thought to fly away from the helipad when the helicopter aligned in the direction he just approached from. As the helicopter rotated to about 90° from his approach heading, it suddenly and very violently made a dramatic increase in right yaw.
Realizing the helicopter was going to be uncontrollable, the pilot “dumped the collective” and tried to stay over the helipad. He stated that after the helicopter struck the helipad, it rolled left and continued spinning on its side, and eventually came to a stop.
The pilot shut down the engines and all three occupants exited unassisted.
The NTSB say that:
A review of a witness video, (See figure 1), taken from an adjacent building, revealed the helicopter approached the rooftop helipad while slowly rotating clockwise about the vertical axis.
The helicopter stopped descending and rotated 360°. The helicopter then descended while rotating an additional 180° and rolled to the left before impacting the helipad. The main rotor blades contacted the helipad, followed by the left main landing gear and the fuselage. The helicopter descended out of view of the camera.
The helicopter came to rest on its left side, on the helipad.
The four composite blades of the main rotor system fragmented and separated, spreading debris throughout the rooftop and down to the ground. The tail rotor and 90° gearbox separated and were found on the rooftop. The left main landing gear separated and remained near the attachment points of the fuselage.
The NTSB investigation continues. We will update this article when the NTSB releases more information.
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