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ASN Wikibase Occurrence # 198355
Last updated: 19 May 2021
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Type:Silhouette image of generic PA22 model; specific model in this crash may look slightly different
Piper PA-22-135 Tri-Pacer
Registration: N2591A
MSN: 22-876
Fatalities:Fatalities: 0 / Occupants: 1
Other fatalities:0
Aircraft damage: Substantial
Location:Panola County SSW of Marshall, TX -   United States of America
Phase: Landing
Departure airport:Jefferson, TX (24F)
Destination airport:Gladewater, TX (07F)
Investigating agency: NTSB
The commercial pilot reported that, about 2 hours into the pipeline surveillance flight, the engine began running roughly. He initially established a course to a nearby airport; however, the engine was not producing enough power to maintain altitude. He subsequently executed a forced landing to a pasture, which resulted in substantial damage to the left wing.

A postaccident engine examination revealed that the No. 3 cylinder exhaust valve fractured at the stem seat. Metallurgical examination revealed that the fracture features were consistent with torsional loading at fracture. The stem was tapered adjacent to the fracture, and interconnected voids and surface oxidation were observed at the fracture surface. The presence of voids, tapering of the stem, and oxidation are consistent with high-temperature deformation under stress. Further examination revealed grain structure and subsurface oxidation consistent with exposure to elevated temperatures over an extended period of time, consistent with a stuck valve condition.

Factors leading to stuck exhaust valves include excessive engine temperature, dirty or contaminated engine oil, high lead content fuels, hot engine shut-downs, and poor engine baffling. Running engines past the recommended overhaul interval or at elevated temperatures risks creating an exhaust valve fatigue event. The investigation was unable to determine the exact combination of elements that led to the stuck valve. However, based on the available maintenance records, the most recent engine overhaul was completed in 1968, and it is likely that the extended 49-year interval contributed to the stuck valve. While this exceeded the engine manufacturer's 12-year or 1,500-hour time between overhaul interval, the operator was not required to comply under current regulations due to the type of operation.

Probable Cause: A stuck exhaust valve, which resulted in the failure of the valve and a loss of engine power. Contributing to the valve failure and loss of engine power was the extended time since the last overhaul.



FAA register:

Accident investigation:
Investigating agency: NTSB
Status: Investigation completed
Duration: 1 year and 11 months
Download report: Final report

Revision history:

14-Aug-2017 21:58 Geno Added
15-Jul-2019 18:07 ASN Update Bot Updated [Time, Operator, Departure airport, Destination airport, Source, Narrative, Accident report, ]

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