Accident Air Tractor AT-401 N1012T,
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ASN Wikibase Occurrence # 288951
 
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Date:Tuesday 16 August 2011
Time:08:00 LT
Type:Silhouette image of generic AT3P model; specific model in this crash may look slightly different    
Air Tractor AT-401
Owner/operator:
Registration: N1012T
MSN: 401-0719
Total airframe hrs:7300 hours
Engine model:GE Aviation Czech M601E-11
Fatalities:Fatalities: 0 / Occupants: 1
Aircraft damage: Substantial
Category:Accident
Location:Hardin, Montana -   United States of America
Phase: Take off
Nature:Agricultural
Departure airport:Hardin, MT
Destination airport:Hardin, MT
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
The pilot reported that, shortly after takeoff for the aerial application flight, the engine quit. He did not have sufficient altitude to restart the engine, so he made a forced landing to an open field; the airplane came to rest upright, and the airframe sustained structural damage.

A visual examination of the engine at the accident site revealed that the compressor section had sustained fire damage and that the turbine section had broken and missing vanes. Postaccident metallurgical examination revealed that one of the turbine wheel blades had fractured and that the fracture surfaces revealed signatures consistent with fatigue propagation and subsequent failure. About 1 year 5 months before the accident, an examination of the engine revealed excessive wear to the combustor outer liner lugs, and the engine was determined to be unserviceable. About 1 year 1 month later (about 4 months before the accident), the airplane underwent a 100-hour inspection and was returned to service in an airworthy condition. No evidence was found indicating that the engine was overhauled or replaced during the 1-year period between when it was determined to be unserviceable and when it was returned to service. The pilot reported that the airplane had undergone a 100-hour inspection 1 week before the accident, but no entries were found pertaining to the inspection in the airplane's maintenance logbooks. The engine had accrued 2,819.6 hours since major overhaul. No evidence was found indicating that the engine was inspected in accordance with the manufacturer's recommended time between overhaul inspection interval of 2,000 hours. It is likely that proper maintenance inspections would have detected the crack and wear in the engine.

Probable Cause: The loss of engine power during takeoff due to the fatigue failure of the turbine wheel blades, which resulted from inadequate maintenance and inspections.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: WPR11LA386
Status: Investigation completed
Duration: 3 years and 5 months
Download report: Final report

Sources:

NTSB WPR11LA386

Location

Revision history:

Date/timeContributorUpdates
05-Oct-2022 08:07 ASN Update Bot Added

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