Aviation Accident Summaries

Aviation Accident Summary FTW95LA105

EL INDIO, TX, USA

Aircraft #1

N6SR

BELL 47G-4A

Analysis

THE HELICOPTER, BEING USED FOR PREDATOR CONTROL, WAS 25 FEET ABOVE THE GROUND AND WAS CHASING A BOBCAT. THE PILOT SAID A RIGHT QUARTERING TAILWIND GUST CAUSED THE HELICOPTER TO LOSE TAIL ROTOR EFFECTIVENESS AND IT BEGAN SPINNING TO THE RIGHT. THE PILOT INCREASED COLLECTIVE AND THROTTLE IN AN ATTEMPT TO REGAIN AIRSPEED, BUT THIS CAUSED THE MAIN ROTOR RPM TO DROOP AND ALTITUDE WAS INSUFFICIENT TO ALLOW THE HELICOPTER TO REGAIN AIRSPEED BY LOWERING THE NOSE. THE PILOT THEN REDUCED COLLECTIVE TO REGAIN RPM, BUT THE HELICOPTER CONTINUED TO SPIN AND IMPACTED THE TERRAIN.

Factual Information

On February 1, 1995, approximately 1500 central standard time, a Bell 47G-4A, N6SR, was destroyed when it impacted terrain while maneuvering near El Indio, Texas. The airline transport rated pilot and one passenger were not injured, but a second passenger received minor injuries. Visual meteorological conditions prevailed. The following is based on the pilot/operator report. The helicopter was being used for predator control and was chasing a bobcat about 25 feet above the ground. The pilot said a right quartering tailwind gust caused the helicopter to lose tail rotor effectiveness and it began spinning to the right. He increased collective and throttle in an attempt to regain airspeed, but this caused the main rotor RPM to droop and altitude was insufficient to allow the helicopter to regain airspeed by diving. He then reduced collective to regain RPM, but the helicopter continued to spin and impacted the terrain.

Probable Cause and Findings

THE LOSS OF TAIL ROTOR EFFECTIVENESS. A FACTOR WAS THE GUSTY RIGHT QUARTERING TAILWIND.

 

Source: NTSB Aviation Accident Database

Get all the details on your iPhone or iPad with:

Aviation Accidents App

In-Depth Access to Aviation Accident Reports