Thursday, May 25, 2017

Bell 47G-3B, N160CS, Custom Air LLC: Accident occurred October 05, 2015 in Huntsville, Walker County, Texas

Aviation Accident Final Report - National Transportation Safety Board: https://app.ntsb.gov/pdf

Investigation Docket - National Transportation Safety Board: https://dms.ntsb.gov/pubdms  

Aviation Accident Data Summary - National Transportation Safety Board: https://app.ntsb.gov/pdf

The National Transportation Safety Board did not travel to the scene of this accident.

Additional Participating Entity: 
Federal Aviation Administration / Flight Standards District Office; Houston, Texas 

Custom Air LLC: http://registry.faa.gov/N160CS

NTSB Identification: CEN16LA003
14 CFR Part 137: Agricultural
Accident occurred Monday, October 05, 2015 in Huntsville, TX
Probable Cause Approval Date: 01/18/2017
Aircraft: BELL 47G, registration: N160CS
Injuries: 1 Minor.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

The commercial pilot was conducting an agricultural application flight in the helicopter. He reported that the helicopter felt "awkward" during the spray pass shortly before the event but that he thought that it was due to an uncoordinated turn. During the next spray pass, the helicopter developed a right rolling tendency, which the pilot was initially able to counter with left cyclic control. He then entered a right turn with the intention of returning to the fuel truck. Once the right turn was initiated, he applied full left and aft cyclic control input but the helicopter did not respond. The helicopter began to lose altitude, impacted the ground, and then came to rest in an open field covered with low vegetation.

The pilot reported that he did not feel any abnormal vibrations or hear any "pops" before the loss of control authority. He added that the flight went from routine to out of control in a matter of "seconds." A postaccident examination of the helicopter revealed no evidence of preimpact failures or malfunctions; however, the extent of damage to the flight control system precluded a complete examination.

The National Transportation Safety Board determines the probable cause(s) of this accident as follows:
The pilot's loss of helicopter control during an agricultural application pass for reasons that could not be determined due to the extent of damage to the flight control system.

On October 5, 2015, about 0805 central daylight time, a Bell 47G-3B helicopter, N160CS, sustained substantial damage when it impacted terrain during an aerial application pass near Huntsville, Texas. The pilot sustained minor injuries. The helicopter was registered and operated by Custom Air LLC under the provisions of 14 Code of Federal Regulations Part 137 as an agricultural application flight. Day visual meteorological conditions prevailed for the flight, which was not operated on a flight plan. The local flight originated from a temporary landing site near the application field shortly before the accident.

The pilot reported that the helicopter felt "awkward" shortly before the event, but thought it was due to an uncoordinated turn. During the next spray pass, the helicopter developed a right rolling tendency, which the pilot was initially able to counter with left cyclic control. He entered a "gentle" right turn with the intention of returning to the fuel truck for a precautionary landing. However, full left cyclic control input was ultimately ineffective in countering the right rolling tendency. The right turn continued for about 150 degrees of heading change. The helicopter began to lose altitude during the turn and subsequently impacted the ground in a slight right bank, traveling about 40 yards before coming to rest. The pilot stated that he did not feel any abnormal vibrations or hear any "pops" before the loss of control authority. He commented that the flight went from routine to out of control in a matter of "seconds."

The helicopter came to rest in an open field covered with low vegetation. A postaccident examination was conducted by Federal Aviation Administration inspectors. The windshield/canopy had separated from the fuselage, with plexiglass fragments observed at the accident site. The forward fuselage structure exhibited minor deformations and distortions; however, the integrity of the fuselage was intact. The main rotor blades remained attached to the hub; however, the rotor blades were deformed over the span of the blades. The rotor hub remained attached to the mast and transmission. The transmission and supporting structure were dislocated from the aft fuselage/forward tailboom truss structure. The fuel tanks were separated and located with the main wreckage. The tailboom was deformed. The tail rotor transmission had separated from tail boom and was located at the accident site. The tail rotor blades remained attached to the hub. The blades exhibited tip damage but appeared otherwise intact. The flight control system components were deformed and fragmented consistent with the overall impact damage.

The postaccident examination did not reveal any anomalies consistent with a preimpact failure or malfunction; however, the examination was hindered by the extent of the damage.

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