Event CHI89FA071

1989-04-11 MILWAUKEE, Wisconsin, United States Serious 1 aircraft Status: Completed

Registry · N4247U

FAA Aircraft Registry record.

Make / Model

AIR TRACTOR INC AT-802

Year of manufacture

2009

Engine

P&W CANADA PT6A-67F (1796 hp)

Seats / Engines

2 seats · 1 engine

Last airworthiness date

20231011

ADS-B equipped

Yes — Mode-S A50DDB

Registrant of record

HIGGINS LEASING INC

Source: FAA Aircraft Registry (releasable master file).

Aircraft involved

N4247U Sikorsky S-58T Serious

Probable cause & findings

DISCONNECT OF THE TAILROTOR DRIVE SHAFT COUPLING.

Factual narrative

THE ACCIDENT HELICOPTER DESCENDED INTO SLOPING TERRAIN AND ROLLED OVER WHILE PERFORMING EXTERNAL LOAD OPERATIONS. THE HELICOPTER HAD JUST PICKED UP A LOAD AND WAS MOVING LATERALLY WHEN IT SUSTAINED A LOSS OF ANTI-TORQUE CONTROL AND THE FUSELAGE STARTED AN UNCOMMANDED AND UNCONTROLLED ROTATION TO THE RIGHT. THE PIC WAS ABLE TO JETTISON HIS EXTERNAL LOAD INTO A CLEAR AREA AND MOVE THE HELICOPTER AWAY FROM OBSTRUCTIONS BEFORE INITIATING AN OUT OF GROUND EFFECT HOVERING AUTOROTATION. Source: NTSB Aviation Accident Database (Pre-2008 Archive) Retrieved: 2026-02-12

Verbatim from NTSB's published report. Source file NTSB_1989_CHI89FA071.txt. Findings + structured fields enriched from FAA avall.mdb. Full investigation docket on data.ntsb.gov ↗.

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