Accident PZL M-18A Dromader N92640,
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ASN Wikibase Occurrence # 289056
 
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Date:Monday 25 July 2011
Time:13:17 LT
Type:Silhouette image of generic M18 model; specific model in this crash may look slightly different    
PZL M-18A Dromader
Owner/operator:Forest Air Services Inc
Registration: N92640
MSN: 1Z025-22
Total airframe hrs:2934 hours
Engine model:Honeywell TPE331-11U-61
Fatalities:Fatalities: 0 / Occupants: 1
Aircraft damage: Substantial
Category:Accident
Location:Anderson, Indiana -   United States of America
Phase: Manoeuvring (airshow, firefighting, ag.ops.)
Nature:Agricultural
Departure airport:Marion, IN
Destination airport:Marion, IN
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
The pilot was marking a field in preparation for an aerial application when he experienced what he thought was an engine failure. He stated that the engine was still running, but it was not producing power. The pilot pushed the power lever forward; the engine power did not increase, but the engine temperature increased. He stated that the engine was idling fast and that he forced the airplane into a bean field about 150 to 200 yards ahead of a tree line. The pilot ground looped the airplane before contacting the trees. A postaccident examination of the engine did not reveal any anomalies. A bench test of the propeller governor revealed that the maximum speed was above the nominal limit and the minimum speed was below the nominal limit. The control lever position was set higher than the specified position, which indicated that the governor had been adjusted in an attempt to regulate the propeller speed. X-rays and a teardown revealed that the propeller governor speeder spring was fractured. A metallurgical examination revealed a preexisting fatigue crack that, over time, resulted in the failure of the spring. The failed speeder spring would have resulted in a loss of oil pressure to the propeller piston, which allowed the propeller blades to rotate to a high blade angle, which then decreased the engine speed and overall power output of the engine. Maintenance records showed the propeller governor was overhauled on May 19, 2009. The speeder springs did not have serial numbers, and, therefore, the maintenance history of the speeder spring could not be determined.

Probable Cause: The fatigue failure of the propeller governor speeder spring, which resulted in the pilot's inability to control engine output power.

Accident investigation:
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Investigating agency: NTSB
Report number: CEN11LA512
Status: Investigation completed
Duration: 2 years 1 month
Download report: Final report

Sources:

NTSB CEN11LA512

History of this aircraft

Other occurrences involving this aircraft
15 February 1996 N92640 Farmers Aerial Service Inc 0 Blythe, CA w/o
10 July 2010 N92640 Canam Aviators Inc 0 Muncie, Indiana sub

Location

Revision history:

Date/timeContributorUpdates
05-Oct-2022 09:18 ASN Update Bot Added

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