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NTSB Report
August 25, 1983 · Air Tractor AT-301 · N8511S
Redwood, MS
Overview
Report Status
Preliminary report
Event Type
Accident
Date
August 25, 1983
Injury Outcomes
No injuries (1 uninjured)
Location
Redwood, MS
Aircraft
Air Tractor AT-301
Tail Number
N8511S
Operator
Martin L Hallman
Injuries
None
Aircraft Damage
Substantial
NTSB Number
ATL83FKQ03
THE ACFT MADE A FORCED LANDING IN A SOYBEAN FIELD AFTER SEVERE VIBRATION DEVELOPED DURING A SPRAYING OPERATION. THE PILOT STATED THAT THE POWERPLANT AND FLT CONTROLS WERE FUNCTIONING NORMALLY AT THE TIME OF THE ACCIDENT. AN ON-SCENE INVESTIGATION REVEALED THAT THE COUNTERWEIGHT BEARING SHAFT (P/N 63546) BROKE ALLOWING THE PROPELLER BLADE TO GO TO HIGHER PITCH WHILE THE OTHER BLADE REMAINED AT CRUISE PITCH SETTING. EXAMINATION OF BOTH PROPELLER BLADE COUNTERWEIGHTS REVEALED THAT THE INTERNAL PARTS HAD MINIMUM AMOUNT OF LUBRICATION. THE SHAFT THAT BROKE WAS ALSO RUSTY AND THE INNER BEARING RACE WAS BROKEN WITH 5 BALL BEARING MISSING. THERE WERE OTHER MAINTENANCE DICREPANCIES ON THIS SHAFT ASSEMBLY. THE TOTAL TIME OF THIS HAMILTON STANDARD 12D40 PROPELLER IS UNKNOWN. THE TIME SINCE THE ACFT WAS INSPECTED IS 194 HOURS.
Full Narrative
THE ACFT MADE A FORCED LANDING IN A SOYBEAN FIELD AFTER SEVERE VIBRATION DEVELOPED DURING A SPRAYING OPERATION. THE PILOT STATED THAT THE POWERPLANT AND FLT CONTROLS WERE FUNCTIONING NORMALLY AT THE TIME OF THE ACCIDENT. AN ON-SCENE INVESTIGATION REVEALED THAT THE COUNTERWEIGHT BEARING SHAFT (P/N 63546) BROKE ALLOWING THE PROPELLER BLADE TO GO TO HIGHER PITCH WHILE THE OTHER BLADE REMAINED AT CRUISE PITCH SETTING. EXAMINATION OF BOTH PROPELLER BLADE COUNTERWEIGHTS REVEALED THAT THE INTERNAL PARTS HAD MINIMUM AMOUNT OF LUBRICATION. THE SHAFT THAT BROKE WAS ALSO RUSTY AND THE INNER BEARING RACE WAS BROKEN WITH 5 BALL BEARING MISSING. THERE WERE OTHER MAINTENANCE DICREPANCIES ON THIS SHAFT ASSEMBLY. THE TOTAL TIME OF THIS HAMILTON STANDARD 12D40 PROPELLER IS UNKNOWN. THE TIME SINCE THE ACFT WAS INSPECTED IS 194 HOURS.
Flight
Event TypeAccident
Event Time10:00 CDT
Nearest Airport0nm N
Runway0
Flight Plan FiledNone
Aircraft FireNo
Aircraft ExplosionNo
Aircraft
AircraftAir Tractor AT-301
Tail NumberN8511S
Aircraft CategoryAir
DamageSubstantial
OperatorMartin L Hallman
Operating RulePart 137
Engines1
Engine TypeReciprocating
Engine DetailsP&W · R-1340-AN1 · Reciprocating · 600
Seats1
People & Injuries
Injury SummaryNo injuries (1 uninjured)
Fatal0
Serious0
Minor0
Uninjured1
Total1
Crew 1Age 49 · Second Class
Conditions
ConditionsVMC
LightDaylight
WindCalm
Visibility8 sm
CeilingNone
Temperature / Dew Point0 C
Altimeter30.00 inHg
Weather SourcePILO