Air Tractor AT-301A N3651R

Summary

On 22 August 2009 at about 21:15 local time, a Air Tractor AT-301A registered N3651R, operated by Jp's Agricair Inc, was involved in an accident near New Miner, Wisconsin, United States. One person was on board and one had minor injuries. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

22 August 2009 at 21:15

Classification

Accident

Location

New Miner, Wisconsin, United States

Nearest airport

Private

Coordinates

44.1564, -90.0058

Aircraft

Air Tractor AT-301A

Registration

N3651R

Category

Airplane

Engines

1

Operator

Jp's Agricair Inc

Operating rule

Part 137: Agricultural

Purpose of flight

Aerial Application

Phase of flight

Not recorded

Route

Bancroft → Bancroft

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

CEN09LA602

1 person had minor injuries.

A total loss of engine power due to the fatigue failure of the engine torsion shaft. Contributing to the accident was the chrome plating of the shaft by an undetermined maintenance/overhaul facility.

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

Read the full NTSB narrative

The pilot reported a complete loss of engine power about 15 minutes after takeoff during an agricultural application pass. He executed a forced landing into a tree plantation adjacent to the agricultural field. A postaccident inspection of the engine revealed that the torsion shaft had separated near the forward bushing journal. The fracture surfaces exhibited features consistent with fatigue failure. In addition, chromium plating was observed at all three bearing journals. Further examination by NTSB materials engineers determined that the torsion shaft fractured due to fatigue that was likely initiated by cracks in the chromium plate repair of the shaft. The plating itself was porous with radial cracks at all journal locations. Records indicated that the torsion shaft was newly overhauled when it was installed in the engine, about 3 1/2 years prior to the accident. However, detailed records related to the overhaul work were not available and the source of the chrome plating could not be determined. The engine manufacturer stated that chrome plating was not specified for production parts, nor was it permitted during component overhaul. A service bulletin recommending replacement of the torsion shaft had not been completed. The bulletin recommended replacement of the original (long) torsion shaft with a shorter shaft. The bulletin noted that the long torsion shafts were susceptible to bushing and bushing journal wear, which would be reduced by installation of the short torsion shafts.

Quoted verbatim from the NTSB record.