Air Tractor AT 301 N8593S

Summary

On 12 June 2014 at about 17:00 local time, a Air Tractor AT 301 registered N8593S, operated by Smith Company Flying Service, was involved in an accident near Pearsall, Texas, 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

12 June 2014 at 17:00

Classification

Accident

Location

Pearsall, Texas, United States

Coordinates

28.8800, -99.0895

Aircraft

Air Tractor AT 301

Registration

N8593S

Category

Airplane

Year built

1978

Engines

1

Operator

Smith Company Flying Service

Operating rule

Part 137: Agricultural

Purpose of flight

Aerial Application

Phase of flight

Not recorded

Route

Pearsall → Pearsall

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

CEN14LA287

Nobody was injured.

The failure of the No. 1 cylinder rod at the link pin. Contributing to the accident was oil starvation to the rod bearing due to the improper flushing of the oil cooler, which allowed metal and other debris in the oil to clog the drain and the led to the piston’s failure.

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

Read the full NTSB narrative

The pilot reported that, while returning to the airport after spraying a cornfield, he noticed that the engine cylinder head temperature was high. After landing, he checked the engine cylinders for discrepancies and found none, so he decided to continue the spraying operations at the cornfield. As the pilot pulled up the airplane from a spray run, the engine started to vibrate and lose power. He subsequently made a forced landing in a nearby field, which resulted in the airplane sustaining substantial damage to both wings. During postaccident examination, a considerable amount of metal was found in the oil drain. The No. 2 cylinder front spark plug was loose. After removing all of the spark plugs, an attempt was made to rotate the engine, but it seized. After removing the No. 1 cylinder, it was discovered that the piston rod had broken at the link pin; no other rods were broken. The No. 1 cylinder link pin was scored, and there was evidence of oil starvation at the rod bearing. According to the operator, the engine had accrued about 100 hours since it had received extensive maintenance, including the replacement of the crankshaft. It is likely that the oil cooler was not properly flushed when the crankshaft was replaced and that metal and other debris remained in the oil, clogged the drain, and caused the piston to fail.

Quoted verbatim from the NTSB record.