Accident Air Tractor AT-301 N8793S,
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ASN Wikibase Occurrence # 296743
 
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Date:Thursday 22 August 2002
Time:06:30 LT
Type:Silhouette image of generic AT3P model; specific model in this crash may look slightly different    
Air Tractor AT-301
Owner/operator:Spain Air
Registration: N8793S
MSN: AT 301-0195
Total airframe hrs:13904 hours
Engine model:Pratt & Whitney R1340
Fatalities:Fatalities: 0 / Occupants: 1
Aircraft damage: Substantial
Category:Accident
Location:DOS PALOS, California -   United States of America
Phase: Unknown
Nature:Agricultural
Departure airport:DOS PALOS, CA (KPVT)
Destination airport:DOS PALOS, CA (KPVT)
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
During cruise flight the engine started to vibrate and the pilot made a forced landing in a newly plowed field and the airplane nosed over after encountering soft soil. The pilot had been crop dusting for about 7.5 hours when the event occurred. The outboard portion of one of the propeller blades had separated. A review of the airframe records indicated that the propeller was overhauled about 10 months prior to the accident. A metallurgical examination of the failed blade revealed it had failed as a result of fatigue cracking that originated from a nick, located on the flat side of the blade's leading edge. Also observed were groove marks that were relatively uniform and consistent with tool marks left by a file. In accordance with the overhaul manual, a field repair can be done to grind or file out corrosion of the blade, with a dye penetrant inspection to detect any visible damage or cracks (Hamilton Standard 130B Blade Overhaul Manual). The overhaul manual notes that tool and file marks should be polished out as one of the final steps in the process. According to the FAA approved flight manual, during the preflight walk-around inspection, the pilot is to inspect the propeller blades for nicks and cracks.

Probable Cause: the failure of the propeller blade due to fatigue. Factors in the accident were the inadequate maintenance-repair of the blade, and, inadequate pilot preflight inspections.

Accident investigation:
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Investigating agency: NTSB
Report number: LAX02LA257
Status: Investigation completed
Duration: 2 years and 4 months
Download report: Final report

Sources:

NTSB LAX02LA257

Revision history:

Date/timeContributorUpdates
14-Oct-2022 10:14 ASN Update Bot Added

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