Accident Air Tractor AT 301 N8593S,
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ASN Wikibase Occurrence # 290553
 
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Date:Thursday 12 June 2014
Time:12:00 LT
Type:Silhouette image of generic AT3P model; specific model in this crash may look slightly different    
Air Tractor AT 301
Owner/operator:Smith Company Flying Service
Registration: N8593S
MSN: 301-0157
Year of manufacture:1978
Total airframe hrs:8357 hours
Engine model:P&W R 1340-AN-1
Fatalities:Fatalities: 0 / Occupants: 1
Aircraft damage: Substantial
Category:Accident
Location:Pearsall, Texas -   United States of America
Phase: Manoeuvring (airshow, firefighting, ag.ops.)
Nature:Agricultural
Departure airport:Pearsall, TX (T30)
Destination airport:Pearsall, TX (T30)
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
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.

Probable Cause: 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.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: CEN14LA287
Status: Investigation completed
Duration: 1 year
Download report: Final report

Sources:

NTSB CEN14LA287

History of this aircraft

Other occurrences involving this aircraft
12 June 2013 N8593S Private 0 Field near Pearsall, Texas sub

Location

Revision history:

Date/timeContributorUpdates
06-Oct-2022 16:30 ASN Update Bot Added

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