Accident Grumman G-164 Tubo Ag-Cat N3629F,
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ASN Wikibase Occurrence # 315339
 
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Date:Friday 30 July 2021
Time:14:23 LT
Type:Silhouette image of generic G64T model; specific model in this crash may look slightly different    
Grumman G-164 Tubo Ag-Cat
Owner/operator:Haley's Flying Service
Registration: N3629F
MSN: 745B
Year of manufacture:1984
Total airframe hrs:197778 hours
Engine model:Garrett/Honeywell TPE331-2
Fatalities:Fatalities: 0 / Occupants: 1
Aircraft damage: Substantial
Category:Accident
Location:Tracy, California -   United States of America
Phase: Manoeuvring (airshow, firefighting, ag.ops.)
Nature:Agricultural
Departure airport:Tracy, CA (NA)
Destination airport:Tracy, CA (NA)
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
The pilot reported that he was performing a low-level agricultural pesticide application on a hay field when the engine suddenly lost all power. Although the airplane was at a high airspeed at the time, the pilot was unable to climb due to the presence of high-tension powerlines above him in his flightpath. During the subsequent descent, he flew beneath a set of powerlines, turned, and landed in a field after his airspeed had decreased. During the landing, the airplane contacted the ground and trees, which resulted in substantial damage to the fuselage and wings.
Postaccident examination of the engine and accessories did not reveal any mechanical anomalies that could have precluded normal operation. Evidence of rotational scoring and metal spray deposits in the engine indicate that it was operating at the time of impact. The fuel solenoid shutoff valve was in the CLOSED position, which would have prevented fuel flow to the engine. However, due to the overwhelming evidence that the engine was rotating at the time of impact, it is likely that the shutoff valve moved to the CLOSED position as a result of the impact.
Propeller signatures indicated that the blades impacted the ground while rotating at low power. An examination of the propeller did not reveal any visible discrepancies that would have affected performance prior to impact. The damage to the start lock brackets, start lock plates, and a contact mark on the internal surface of the piston suggest the propeller was on or below the start lock angle at impact. This was likely the result of impact forces, as the pilot stated that he did not reduce throttle input or attempt to feather blades before impact. Previous maintenance indicated that the blade radius was properly set.
The pilot did not recall the power lever position at the time of the power loss and the investigation did not reveal any evidence of preimpact mechanical malfunctions or failures. Therefore, the reason for the pilot's reported loss of power could not be determined.

Probable Cause: A loss of thrust during a low-level agricultural application flight, which resulted in a descent and impact with terrain. The reason for the loss of thrust could not be determined based on available information.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: WPR21LA299
Status: Investigation completed
Duration: 1 year and 10 months
Download report: Final report

Sources:

NTSB WPR21LA299

Location

Revision history:

Date/timeContributorUpdates
16-Jun-2023 13:29 ASN Update Bot Added

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