NTSB Identification: LAX94LA268.
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Accident occurred Tuesday, June 28, 1994 in FIREBAUGH, CA
Probable Cause Approval Date: 03/30/1995
Aircraft: ROCKWELL S2-R, registration: N4230X
Injuries: 1 Fatal.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

THE AIRPLANE WAS LOADED WITH 2,000 POUNDS OF POWDERED SULFUR. A WITNESS SAID THE AIRPLANE HAD JUST COMPLETED A SPRAY RUN, AND BEGAN A LEFT TURN TO MAKE WHAT THE WITNESS ASSUMED WAS A SOUTHBOUND RUN ON THE FIELD. FLAMES WERE SEEN ON THE BOTTOM OF THE AIRPLANE IN THE VICINITY OF THE DISPENSER APPARATUS. THE AIRPLANE DESCENDED A LITTLE, STARTED TO CLIMB AGAIN, THEN SUDDENLY NOSED OVER AND DOVE VERTICALLY INTO THE GROUND. INFLIGHT AND POSTCRASH FIRE HAD TOTALLY CONSUMED ALL OF THE NON-STEEL AIRCRAFT COMPONENTS, AND THE FIRE SEEMED TO HAVE BEEN MORE INTENSE IN THE AREA OF THE CHEMICAL HOPPER AND SPRAY APPARATUS. THE CHEMICAL MANUFACTURER SAID THE POWDERED SULFUR DUST USED IN AG OPERATIONS IS A MODERATE FIRE HAZARD ACCORDING TO NFPA CRITERIA. THE COMPOUND HAS A FLASH POINT OF 374 DEG F, YET STUDIES SHOW THAT CLOUDS OF DUST MAY IGNITE AT IGNITION TEMPS OF 190 DEG IN DENSITY LIMITS OF LESS THAN 0.1 OUNCES PER CUBIC FOOT.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

THE PILOT'S LOSS OF AIRCRAFT CONTROL AS A RESULT OF INCAPACITATION FROM AN IN-FLIGHT SULFUR FIRE.

Full narrative available

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