Accident · 1991-04-05

What the record says

Event date

1991-04-05

Event type

Accident

Highest injury level

Fatal injury

Aircraft

EMBRAER EMB-120RT (N270AS)

Operating rule

Part 135

Operator

Atlantic Southeast Airlines, Inc. Operator named in NTSB report

Operated by (per NTSB report)

ATLANTIC SOUTHEAST AIRLINES

Probable cause

THE LOSS OF CONTROL IN FLIGHT AS A RESULT OF A MALFUNCTION OF THE LEFT ENGINE PROPELLER CONTROL UNIT WHICH ALLOWED THE PROPELLER BLADE ANGLES TO GO BELOW THE FLIGHT IDLE POSITION. CONTRIBUTING TO THE ACCIDENT WAS THE DEFICIENT DESIGN OF THE PROPELLER CONTROL UNIT BY HAMILTON STANDARD AND THE APPROVAL OF THE DESIGN BY THE FEDERAL AVIATION ADMINISTRATION. THE DESIGN DID NOT CORRECTLY EVALUATE THE FAILURE MODE THAT OCCURRED DURING THIS FLIGHT, WHICH RESULTED IN AN UNCOMMANDED AND UNCORRECTABLE MOVEMENT OF THE BLADES OF THE AIRPLANE'S LEFT PROPELLER BELOW THE FLIGHT IDLE POSITION. (NTSB REPORT AAR-92/03)

Flight crew

Flight-crew details for this event aren't in the NTSB database extract we hold (its coverage starts with 2008 events) — a gap in our data, not an absence of crew.