Flight CTLS N106SF

Summary

On 25 April 2014 at about 22:42 local time, a Flight CTLS registered N106SF was involved in an accident near Greenville, Texas, United States. 2 people were on board and 2 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

25 April 2014 at 22:42

Classification

Accident

Location

Greenville, Texas, United States

Nearest airport

Majors Airport (GVT)

Coordinates

33.0678, -96.0653

Aircraft

Flight CTLS

Registration

N106SF

Category

Airplane

Year built

2009

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Route

Gilmer → Denton

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

CEN14LA226

2 people had minor injuries.

The fatigue failure of the No. 4 cylinder exhaust valve due to excessive wear of the corresponding train tappet, which resulted in a total loss of engine power.

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

Read the full NTSB narrative

The private pilot reported that a routine maintenance inspection had been completed earlier on the day of the accident. During the initial personal flight after the inspection, the engine exhaust gas temperatures (EGT) differed by up to 150 degrees, although they remained within the specified operating limitations. The pilot chose to divert to an intermediate airport to investigate any mechanical issue with the engine. The pilot reported that a mechanic informed him that the EGT difference was not unusual for that particular engine. No significant engine issues were identified, and two subsequent run-ups were normal. A third run-up and subsequent takeoff were also normal. As the flight progressed, the EGT indications were within limitations, and, after 25 minutes, they had equalized. About 5 minutes later, the engine and propeller "stopped abruptly." The pilot's attempts to restore engine power were unsuccessful. He subsequently executed a forced landing to an athletic field. During the landing, the nose landing gear separated, and the airplane nosed over. A postaccident engine examination revealed that the No. 4 cylinder exhaust valve had failed near the valve head due to bending fatigue. The No. 4 cylinder, piston, and exhaust valve head exhibited extensive gouging, scraping, and deformation consistent with secondary damage due to the failed exhaust valve. Further examination revealed that the No. 4 cylinder exhaust train tappet exhibited severe wear, which had significantly reduced the height of the exhaust tappet compared to the height of the intake tappet. The resulting gap in the exhaust valve train due to the shortened tappet likely caused excessive impact loads between the exhaust valve and the cylinder valve seat during engine operation, which resulted in the valve's failure. The subsequent secondary damage due to the separated valve head ultimately caused the catastrophic engine failure.

Quoted verbatim from the NTSB record.