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NTSB Report
March 15, 1991 · Air Tractor AT-401 · N73135
Avon, MS
Overview
Report Status
Probable Cause
Event Type
Accident
Date
March 15, 1991
Injury Outcomes
1 injury (1 serious injury)
Location
Avon, MS
Aircraft
Air Tractor AT-401
Tail Number
N73135
Operator
Longwood Flying Service
Injuries
Serious
Aircraft Damage
Substantial
NTSB Number
MIA91LA101
DURING A TURN FOR A SPRAY PASS, THE PLT STATED THAT THE ENG QUIT. HE THEN OPENED THE CHEMICAL DUMP VALVE & LANDED THE ACFT PERPENDICULAR TO PLOWED ROWS IN A FIELD. THE ACFT THEN NOSED OVER AFTER TOUCHDOWN & THE PLT WHO WAS UNCONSCIOUS, WAS CUT FREE FROM HIS SEATBELT & SHOULDER HARNESS. EXAM OF THE ACFT AT THE ACCIDENT SITE REVEALED THAT THE MAGNETO SWITCH WAS POSITIONED TO 'BOTH.' THE ACFT WAS RECOVERED & THE ENG WAS STARTED & OPERATED NORMALLY WITH THE MAGNETO SWITCH POSITIONED TO THE BOTH POSITION HOWEVER WHEN THE MAGNETO SWITCH WAS POSITIONED TO THE LT POSITION, THE ENG QUIT. THE LT MAGNETO WAS REMOVED FOR DISASSEMBLY. EXAM OF THE LT MAGNETO REVEALED THAT A PHENOLIC GEAR WHICH DRIVES THE ROTATING MAGNET WAS DAMAGED WHICH PREVENTED THE MAGNETO FROM PRODUCING SPARK. NO DETERMINATION COULD BE MADE AS TO THE REASON FOR THE LOSS OF ENG POWER.
NTSB Probable Cause
LOSS OF ENGINE POWER FOR UNDETERMINED REASONS DURING A TURN WHILE ON AN AERIAL APPLICATION FLIGHT. CONTRIBUTING TO THE ACCIDENT WAS FAILURE OF THE LEFT MAGNETO DUE TO FAILURE OF A PHENOLIC GEAR WHICH DRIVES THE ROTATING MAGNET.
Full Narrative
DURING A TURN FOR A SPRAY PASS, THE PLT STATED THAT THE ENG QUIT. HE THEN OPENED THE CHEMICAL DUMP VALVE & LANDED THE ACFT PERPENDICULAR TO PLOWED ROWS IN A FIELD. THE ACFT THEN NOSED OVER AFTER TOUCHDOWN & THE PLT WHO WAS UNCONSCIOUS, WAS CUT FREE FROM HIS SEATBELT & SHOULDER HARNESS. EXAM OF THE ACFT AT THE ACCIDENT SITE REVEALED THAT THE MAGNETO SWITCH WAS POSITIONED TO 'BOTH.' THE ACFT WAS RECOVERED & THE ENG WAS STARTED & OPERATED NORMALLY WITH THE MAGNETO SWITCH POSITIONED TO THE BOTH POSITION HOWEVER WHEN THE MAGNETO SWITCH WAS POSITIONED TO THE LT POSITION, THE ENG QUIT. THE LT MAGNETO WAS REMOVED FOR DISASSEMBLY. EXAM OF THE LT MAGNETO REVEALED THAT A PHENOLIC GEAR WHICH DRIVES THE ROTATING MAGNET WAS DAMAGED WHICH PREVENTED THE MAGNETO FROM PRODUCING SPARK. NO DETERMINATION COULD BE MADE AS TO THE REASON FOR THE LOSS OF ENG POWER.
Flight
Event TypeAccident
Event Time15:00 CST
Nearest Airport0nm N
Runway0
Runway Length0
Runway Width0
Flight Plan FiledNone
Aircraft FireNo
Aircraft ExplosionNo
Aircraft
AircraftAir Tractor AT-401
Tail NumberN73135
Aircraft CategoryAir
DamageSubstantial
OperatorLongwood Flying Service
Operating RulePart 137
Engines1
Engine TypeReciprocating
Engine DetailsP&W · R1340-AN1 · Reciprocating · 600
Seats1
People & Injuries
Injury Summary1 injury (1 serious injury)
Fatal0
Serious1
Minor0
Uninjured0
Total1
Crew 1Age 59 · Second Class
Conditions
ConditionsVMC
LightDaylight
Wind360° @ 5 kt, gusting 10 kt
Visibility5 sm
CeilingNone
Temperature / Dew Point64 F / 0 C
Altimeter0
Weather SourcePILO