Accident Grumman G-164B Turbo Ag-Cat N6648Q,
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ASN Wikibase Occurrence # 168169
 
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Date:Wednesday 9 July 2014
Time:15:00
Type:Silhouette image of generic G64T model; specific model in this crash may look slightly different    
Grumman G-164B Turbo Ag-Cat
Owner/operator:Ryan A. Gengerke
Registration: N6648Q
MSN: 175B
Year of manufacture:1977
Total airframe hrs:8691 hours
Engine model:Walter M601E11
Fatalities:Fatalities: 0 / Occupants: 1
Aircraft damage: Substantial
Category:Accident
Location:East of Garrison Municipal Airport (D05), Garrison, North Dakota -   United States of America
Phase: Manoeuvring (airshow, firefighting, ag.ops.)
Nature:Agricultural
Departure airport:Garrison, ND (D05)
Destination airport:Garrison, ND (D05)
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
The pilot reported that he was spraying fungicide on a field when the engine lost power and that he then observed white smoke coming from the exhaust stacks. He feathered the propeller, shut the fuel off, and landed the airplane in a wheat field. The airplane struck a barbed wire fence before coming to a stop, which resulted in substantial damage to the forward fuselage.
The examination of the turboprop engine revealed that wear between the power turbine shaft and the quill shaft had led to the disconnection of the power turbine wheel, an overspeed of the power turbine, and a subsequent loss of engine power. During postaccident examination, a considerable amount of extremely fine black particles were found in the oil filter, consistent with excessive spline wear, which appeared to have been occurring for some time. Maintenance records indicated that the last 100-hour inspection of the engine was accomplished 2 days before the accident. It is likely that maintenance personnel did not examine the oil filter during that inspection. If they had examined the oil filter, they would have detected the contaminants, which would have indicated an impending failure of an internal engine component. There have been five similar events involving the same make and model engine, and the manufacturer issued a service bulletin with instructions for inspecting the engine; the Federal Aviation Administration subsequently issued a notice of proposed rulemaking to require the inspection.
Probable Cause: Excessive wear between the power turbine shaft and quill shaft spline, which led to the disconnection of the power turbine wheel, an overspeed of the power turbine, and the subsequent loss of engine power. Contributing to the accident was maintenance personnel’s failure to detect contaminants in the oil filter during the engine’s recent 100-hour inspection.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: CEN14LA358
Status: Investigation completed
Duration:
Download report: Final report

Sources:

NTSB

Location

Revision history:

Date/timeContributorUpdates
31-Jul-2014 04:55 Geno Added
21-Dec-2016 19:28 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]
30-Nov-2017 18:50 ASN Update Bot Updated [Operator, Other fatalities, Departure airport, Destination airport, Source, Narrative]

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