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ASN Wikibase Occurrence # 44556
Last updated: 2 December 2021
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Type:Silhouette image of generic SS2T model; specific model in this crash may look slightly different
Ayres S-2R-T34 Thrush
Owner/operator:Vance Ag
Registration: N4009M
MSN: 6012
Fatalities:Fatalities: 1 / Occupants: 1
Aircraft damage: Substantial
Location:Firebaugh, CA -   United States of America
Phase: Take off
Departure airport:Firebaugh, CA (F34)
Destination airport:
Investigating agency: NTSB
The airplane impacted soft muddy terrain during a forced landing following a loss of engine power shortly after departure. The pilot departed with a full load of fertilizer and climbed above several transmission wires before the engine lost power. The airplane pitched down in a nose-low configuration and dove toward terrain. The engine's most recent inspection occurred about 2 months prior to the accident. The logbook entry for that inspection stated that the mechanic performed a hot section inspection at which time the compressor turbine (CT) disk was reinstalled with 3,595 cycles remaining. A post accident examination of the engine revealed that a CT blade had failed in fatigue initiating in the fir tree root. Near the fatigue origin, no surface damage was observed and no material anomalies were found on the fracture surface; the reason for the fatigue failure was never definitively determined. The blade was likely manufactured under a Parts Manufacturer Approval (PMA). The Safety Board Materials Laboratory reported that the chemistry of the fractured blade appeared to be consistent with the PMA specified alloy and not to the material specification the original equipment manufacturer (OEM) utilizes. A review of the Safety Board database revealed an instance of a very similar failure on an OEM manufactured CT blade. Evidence of recent marijuana use was found on toxicological evaluation, and the pilot might have been impaired ..." It is not clear whether this impairment adversely affected the pilot's actual actions during his response to the loss of engine power.
Probable Cause: the loss of engine power during takeoff climb resulting from the fatigue failure of one of the compressor turbine blades; the cause of the fatigue failure could not be definitively determined.




Revision history:

28-Oct-2008 00:45 ASN archive Added
21-Dec-2016 19:24 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]
06-Dec-2017 07:01 ASN Update Bot Updated [Other fatalities, Source, Narrative]

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