Pilot Debrief

Aerospatiale AS350 near Tampa, FL — 2020-02-18

Final reportERA20CA106
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Date
2020-02-18
Location
Tampa, FL, USA
Airport
VDF
Aircraft
Aerospatiale AS350
Registration
N188FS
Category
Helicopter
Highest injury
None
Fatalities
0
Phase of flight
Maneuvering

Probable cause

The flight instructor's inadvertent throttle reduction below idle, which resulted in a total loss of engine power and subsequent impact with terrain following a power-off autorotation.

NTSB narrative

The flight instructor in the helicopter reported that he directed the pilot receiving instruction to conduct an autorotation with a 180° turn, followed by a power recovery. Abeam the departure end of runway, he moved the throttle lever from the "fly" position to idle. While conducting the maneuver, the pilot overshot the runway and aligned the helicopter with the parallel taxiway. Upon realizing that the helicopter was not in the correct position, the pilots chose to abort the maneuver and perform a go-around. While the pilot continued to fly the helicopter, the instructor inadvertently moved the throttle lever from idle aft toward the "off" position and then forward to the "fly" position. The engine experienced a total loss of power, and the instructor adjusted the throttle to no avail. As the helicopter descended, the pilot requested that the instructor "get on the controls." The instructor took the controls, conducted a power-off autorotation, and landed the helicopter on the taxiway. The helicopter skidded about 180 ft, departed the taxiway onto adjacent grass, and came to rest in a drainage ditch. The instructor reported that there were no preaccident mechanical failures or malfunctions with the helicopter that would have precluded normal operation. The Federal Aviation Administrator inspector who examined the helicopter reported that the left antivibrator mount beam had sustained substantial damage.

Analysis

Primary failure mode
Engine power loss
First missed decision gate
Instructor could have maintained throttle in FLY position during maneuver.

NTSB coding

Evidence available

  • Photos
  • 6 docket documents
View NTSB final reportView NTSB docket

Docket documents6

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