Aviation Accident Summaries

Aviation Accident Summary ATL95LA004

ASHBURN, GA, USA

Aircraft #1

N8971Q

AERO COMMANDER S2R

Analysis

THE COMMERCIAL PILOT HAD COMPLETED SPRAYING OPERATIONS ON A COTTON FIELD. AS HE WAS LEAVING THE AREA, HE BEARD A 'BANG' OR 'PING' SOUND, AUDIBLE ABOVE THE ENGINE NOISE. THE AIRCRAFT BEGAN TO VIBRATE, AND ALTITUDE COULD NOT BE MAINTAINED. HE FORCE LANDED THE AIRCRAFT IN A COTTON FIELD, AND STRUCTURAL DAMAGE RESULTED WHEN THE AIRCRAFT BOGGED DOWN IN THE COTTON PLANTS. A POST- ACCIDENT INSPECTION OF THE PROPELLER REVEALED A BLADE COUNTERWEIGHT BEARING SHAFT HAD FAILED, ALLOWING ONE OF THE BLADES TO GO TO HIGH PITCH.

Factual Information

On October 5, 1994, at 1200 eastern daylight time, an Aero Commander S2R, N8971Q, was substantially damaged during a forced landing near Ashburn, Georgia. The commercial pilot was not injured. The aircraft was operated under the provisions of 14 CFR Part 137 by Coney Ag Service, of Cordele, Georgia. Visual meteorological conditions prevailed at the time, and no flight plan was filed for the local, aerial application flight. The flight originated in Ashburn at 1115. The pilot reported that he was spraying defoliant chemicals on a cotton field. When he was exiting the field, he heard a loud "bang" or "ping", audible above the engine noise. The aircraft started to vibrate, and would not maintain altitude. The only landing site available was a cotton field. During the forced landing, the aircraft bogged down in the cotton plants, and began to nose over. The left wing contacted the ground, pulling the tail back down, and the aircraft came to a stop. An airworthiness inspector from the Federal Aviation Administration visited the accident site, and inspected the aircraft. His inspection of the propeller revealed that a counterweight bearing shaft failed, allowing one blade to go to high pitch during flight. The propeller logbook could not be located, therefore propeller service and overhaul information could not be determined.

Probable Cause and Findings

THE FAILURE OF A BLADE COUNTERWEIGHT BEARING SHAFT, ALLOWING ONE PROPELLER BLADE TO GO TO HIGH PITCH.

 

Source: NTSB Aviation Accident Database

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