Piper PA22 N2591A

Summary

On 14 August 2017 at about 15:17 local time, a Piper PA22 registered N2591A was involved in an accident near Beckville, Texas, United States. One person was on board and one had minor injuries. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

14 August 2017 at 15:17

Classification

Accident

Location

Beckville, Texas, United States

Coordinates

32.2436, -94.4558

Aircraft

Piper PA22

Registration

N2591A

Category

Airplane

Year built

1952

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Aerial Observation

Phase of flight

Not recorded

Route

Jefferson → Gladewater

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

CEN17LA317

1 person had minor injuries.

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.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

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.

Quoted verbatim from the NTSB record.