Pilot Debrief

SIKORSKY 269C near Burnham, ME — 2013-07-03

Final reportERA13LA314
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Date
2013-07-03
Location
Burnham, ME, USA
Aircraft
SIKORSKY 269C
Registration
N888ZW
Category
Helicopter
Highest injury
Serious
Fatalities
0
Phase of flight
Maneuvering

Probable cause

The pilot's failure to maintain yaw control while operating out of ground effect at a low airspeed, which resulted in the loss of tail rotor effectiveness, an uncontrolled descent, and an in-flight collision with trees and terrain. Contributing to the accident was the pilot's failure to recognize that the low-altitude maneuvering during the aerial observation flight could lead to a loss of tail rotor effectiveness.

NTSB narrative

**This report was modified on February 23, 2015. Please see the public docket for this accident to view the original report.** The pilot reported that, during a black bear-tracking flight while flying the helicopter about 50 feet above tree tops at an airspeed of between 10 and 20 knots with a "fairly calm" wind and the engine instruments reading normal, he began a "fading right turn" (that is, a right turn with a sideways component of flight leading into it.) During the turn, the pilot input a "modicum" of left antitorque pedal while slowing. About 2 seconds after initiating the right turn and while the helicopter was about 30 to 40 feet above the trees, the turn escalated into a right (or clockwise) spin about the main rotor axis despite the pilot's left pedal inputs, which is consistent with a sudden loss of tail rotor authority. The helicopter subsequently impacted trees and terrain. The passenger, who had only been flown once previously in a helicopter, reported that the helicopter spun counterclockwise. Postaccident examinations of the airframe, flight controls, main and tail rotor drive system components, engine, and engine accessories revealed no evidence of preimpact failure or malfunction. Although the pilot and passenger descriptions of the direction of the spin were inconsistent, the lack of any mechanical issue with the helicopter or its engine, the pilot's comment that the engine readings were normal at the start of the turn, and the helicopter's flight condition when the loss of control occurred (operating out of ground effect and turning right at a low airspeed) were consistent with a loss of tail rotor effectiveness during the right turn, resulting in a right (clockwise) spin.

Analysis

Primary failure mode
Loss of control
First missed decision gate
Pilot did not check fuel tanks or strainer for contamination before flight.

NTSB coding

Evidence available

  • FDR / data
  • Photos
  • 20 docket documents
View NTSB final reportView NTSB docket

Docket documents20

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