Aviation Accident Summaries

Aviation Accident Summary LAX04LA116

WAHIAWA, HI, USA

Aircraft #1

N1113L

Hughes 369D

Analysis

The commercial helicopter pilot was transporting a sling load of ladders taped together and suspended by a 15-foot line. During the flight, the load shifted, and a ladder struck the tail rotor. The tail rotor separated from the helicopter, and the pilot initiated an emergency autorotation. The helicopter landed at an off-airport site and rolled onto its side. According to the operator's FAA-approved flight manual for external loads, the pilot has the sole responsibility to ensure that the load is properly rigged.

Factual Information

On December 17, 2003, at 1630 Hawaiian standard time, a Hughes 369D helicopter, N1113L, crashed into a remote area after the tail rotor separated from the helicopter 3 miles northeast of the Wheeler Army Airfield (HHI), Wahiawa, Hawaii. Pacific Helicopter Tours Inc., of Kahului, Hawaii, operated the helicopter under the provisions of 14 CFR Part 133 as an external load operation. The helicopter sustained substantial damage. The commercial pilot, the sole occupant, was not injured. Visual meteorological conditions prevailed for the local flight that departed HHI about 1600. No flight plan had been filed, which was scheduled to terminate at HHI. The incident was upgraded to an accident on February 4, 2004; after a review of the operator's contract confirmed that the flight was not a military operation. The University of Hawaii had contracted with Pacific Helicopter Tours to fly people and equipment to various areas around the Army installation at HHI for environmental studies. According to the pilot, the cargo consisted of a net and three ladders. The net was connected to the bell hook and the ladders were also connected to the hook via two 15-foot straps. After takeoff, at an airspeed of 50-60 knots, he felt the load change. He indicated that it felt like the load was released. The nose of the helicopter pitched down and the helicopter rolled to the left. The pilot stated he was able to maintain control by increasing and reducing power. The pilot completed a successful autorotation to a riverbed. After touchdown the helicopter rolled onto its left side. The pilot stated that there were no mechanical anomalies noted with the helicopter prior to the load shift. In the Operator's Rotorcraft-Load Combination Flight Manual Section II Page 6 subsection E External Load Securing Procedures states: "(1) To be determined on an individual load basis by pilot in command who will assume total responsibility for making sure this is done." According to one of the loaders, the three ladders were duck-taped together and attached to the helicopter with two 15-foot straps. They were strapped in such a way that would allow them to "fly in a horizontal position." The loader and crew watched the helicopter takeoff with no discrepancies. They were walking back to their camp when they turned around to watch the helicopter again. They saw the helicopter "slow abruptly", and indicated that the "nose turned up." Simultaneously the ladders "appeared to swing high." The majority of the ground crew watched the helicopter "drop rapidly and out of sight with the load still attached below the ship." One of the crewmembers saw something fall from the load, but didn't know what it was. According to a Federal Aviation Administration (FAA) inspector, who responded to the accident site, the accident flight was the last flight of the day. Contracted loaders placed equipment into a cargo net, and attached it to the external line. The cargo included four ladders: two 12-foot ladders, one 8-foot ladder, and one 6-foot ladder. After takeoff, as the helicopter picked up airspeed the pilot heard a "bang." He felt the helicopter pitch forward and roll left. The pilot entered an autorotation and landed in a riverbed. The FAA inspector stated that one of the 12-foot ladders had shifted during takeoff, and had come back and struck the tail rotor. The tail rotor then separated from the helicopter.

Probable Cause and Findings

The pilot's failure to properly secure the external sling load, which allowed the load to shift, and subsequently strike and remove the tail rotor.

 

Source: NTSB Aviation Accident Database

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