Grumman Acft Eng Cor-Schweizer G-164B N6648Q

Summary

On 9 July 2014 at about 20:00 local time, a Grumman Acft Eng Cor-Schweizer G-164B registered N6648Q, operated by Ryan A. Gengerke, was involved in an accident near Garrison, North Dakota, United States. One person was on board and nobody was injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

9 July 2014 at 20:00

Classification

Accident

Location

Garrison, North Dakota, United States

Coordinates

47.6817, -101.2392

Aircraft

Grumman Acft Eng Cor-Schweizer G-164B

Registration

N6648Q

Category

Airplane

Year built

1977

Engines

1

Operator

Ryan A. Gengerke

Operating rule

Part 137: Agricultural

Purpose of flight

Aerial Application

Phase of flight

Not recorded

Route

Garrison → Garrison

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

CEN14LA358

Nobody was injured.

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.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB 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.

Quoted verbatim from the NTSB record.