Accident Air Tractor 400 N73080,
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ASN Wikibase Occurrence # 356551
 
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Date:Monday 21 October 1996
Time:12:30 LT
Type:Silhouette image of generic AT3T model; specific model in this crash may look slightly different    
Air Tractor 400
Owner/operator:Patterson Air Farming
Registration: N73080
MSN: 400-0639
Year of manufacture:1985
Total airframe hrs:4461 hours
Engine model:P&W PT6A-20
Fatalities:Fatalities: 0 / Occupants: 1
Aircraft damage: Substantial
Category:Accident
Location:Sylvester, GA -   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:
The pilot intentionally operated the engine exceeding the maximum temperature limits during aerial application flights which he was advised against by several different individuals. The pilot stated that during an aerial application flight he first heard a loud sound with a subsequent loss of engine power. He initiated a forced landing in a field and after touchdown with the brakes heavily applied to avoid obstructions ahead, the airplane nosed over. Examination of the engine revealed that 7 of the 58 compressor turbine blades were failed near the midspan or platform. Oxidation was detected at one of the 7 blades and creep and necking was detected at the trailing edge of another of the blades. Additionally, severe burn erosion was noted to the trailing edges of the compressor turbine guide vanes. According to the ASM Metals Handbook, creep is a time dependent strain occurring under stress. Additionally, at elevated temperature, the service life of a metal component subjected to either non-vibratory or vibratory loading is predictably limited.

Probable Cause: Was the pilots intentional disregard for operating the engine contrary to the flight manuals for intentionally exceeding the maximum engine temperature, resulting in creep failure of one of the compressor turbine blades.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: MIA97LA012
Status: Investigation completed
Duration: 1 year and 3 months
Download report: Final report

Sources:

NTSB MIA97LA012

History of this aircraft

Other occurrences involving this aircraft
19 October 1998 N73080 Private 0 Aztec, NM sub

Location

Revision history:

Date/timeContributorUpdates
13-Mar-2024 08:25 ASN Update Bot Added

Corrections or additions? ... Edit this accident description

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