Accident Air Tractor AT-502 N9185F,
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ASN Wikibase Occurrence # 297539
 
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Date:Tuesday 5 March 2002
Time:12:30 LT
Type:Silhouette image of generic AT5T model; specific model in this crash may look slightly different    
Air Tractor AT-502
Owner/operator:Schlater Flying Inc.
Registration: N9185F
MSN: 502-0206
Year of manufacture:1993
Total airframe hrs:6248 hours
Engine model:Pratt & Whitney PT-6A-34
Fatalities:Fatalities: 0 / Occupants: 1
Aircraft damage: Substantial
Category:Accident
Location:Schlater, Mississippi -   United States of America
Phase: Unknown
Nature:Agricultural
Departure airport:Schlater, MS
Destination airport:
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
The pilot stated he was on takeoff roll to conduct aerial application flight. Just before rotation he heard a loud pop and observed sparks in the vicinity of the engine compartment. There was insufficient runway remaining to stop the airplane. The airplane went off the end of the runway and collided with a ditch. Examination of the engine assembly revealed a total failure of several compressor turbine blades. Metallurgical examination of the compressor turbine blades revealed voiding and grain separation were observed toward the tip grain boundary along a reaction zone which is indicative of creep propagation. A comparison of the microstructure at the airfoil tip revealed a significant difference in the structure with the tip appearing to be solutioned. According to the original equipment maintenance manual blade tips that are solutioned is an indication of over temperature. if the inter-turbine temperature exceeds 875-degrees Celsius for 2 seconds the engine is required to be returned to an overhaul facility. It could not be determined when or who exceeded the over temperature limit.

Probable Cause: an unknown person at an unknown time exceeded the engine temperature limitations that resulted in the failure of compressor turbine and the subsequent loss of engine power during takeoff.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: ATL02LA060
Status: Investigation completed
Duration: 1 year and 8 months
Download report: Final report

Sources:

NTSB ATL02LA060

Revision history:

Date/timeContributorUpdates
14-Oct-2022 19:49 ASN Update Bot Added

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