Accident Air Tractor AT-401 N73135,
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ASN Wikibase Occurrence # 365596
 
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Date:Friday 15 March 1991
Time:16:00 LT
Type:Silhouette image of generic AT3P model; specific model in this crash may look slightly different    
Air Tractor AT-401
Owner/operator:Longwood Flying Service, Inc.
Registration: N73135
MSN: 401-0671
Year of manufacture:1987
Total airframe hrs:1675 hours
Engine model:P&W R1340-AN1
Fatalities:Fatalities: 0 / Occupants: 1
Aircraft damage: Substantial
Category:Accident
Location:Avon, MS -   United States of America
Phase: Manoeuvring (airshow, firefighting, ag.ops.)
Nature:Agricultural
Departure airport:
Destination airport:
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
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.

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.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: MIA91LA101
Status: Investigation completed
Duration: 1 year and 11 months
Download report: Final report

Sources:

NTSB MIA91LA101

Location

Revision history:

Date/timeContributorUpdates
20-Mar-2024 11:48 ASN Update Bot Added

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