Flight Design GMBH CTLS accident near Greenville, Texas, April 25, 2014
On April 25, 2014 at about 10:42 pm local time, a 2009 Flight Design GMBH CTLS, registered N106SF, was substantially damaged in an accident during enroute (cruise) near Greenville, Texas (Majors Airport). It was a personal flight under general aviation rules (Part 91). 2 people had minor injuries. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
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.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- April 25, 2014 · about 10:42 pm local time
- Place
- Greenville, Texas · Majors Airport · map
- Type
- Accident
- Injuries
- 2 people had minor injuries.
- Weather
- visual conditions (good weather)
- Aircraft
- Flight Design GMBH CTLS, built 2009 · all CTLSs on the register
- Registration
- N106SF · no longer on the register · serial F-09-10-13
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
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.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
What happened, in order
- Loss of engine power (total) during enroute (cruise) defining event
- Off-field or emergency landing during emergency descent
- Nose over/nose down during landing (landing roll)
The NTSB's findings
- cause Aircraft › Aircraft power plant › Engine (reciprocating) › Recip eng cyl section › Fatigue/wear/corrosion
Pilot
- Certificate: private
- Ratings: single-engine land
- Flight time: 320 hours in all; 194 in this make and model; 74 in the last 90 days; 15 in the last 30 days; 320 as pilot in command
- Last flight review: September 17, 2013
- Medical certificate: Class 3 (with waivers/limitations)
- Seat: left
- Injury: minor injuries
The aircraft
- Airframe total time: 1,613 hours
- Last inspection: annual inspection, April 25, 2014; 5 hours since
- Maximum gross weight: 2,950 lb
- Seats: 2
- Landing gear: fixed
- Engine: Rotax 912ULS (piston); 1,613 hours total
The flight
- Departed from: JXI Gilmer TX at 9:35 pm
- Destination: DTO Denton TX
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 170° at 6 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 79°F (26°C), dew point 34°F (1°C)
- Altimeter: 29.93 inHg
- Observation at 10:35 pm from GVT, 3 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 | |||
| Passengers | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
9 documents, released by the NTSB on May 31, 2016. View them here, or download them; the NTSB redacts some personal details before release, and this site shows the NTSB's own titles rather than its file names.
| # | Document | What it is | |
|---|---|---|---|
| 1 | Pilot/operator Aircraft Accident Report, NTSB Form 6120.1 | PDF, 9 pages | View Download |
| 2 | Pilot's Statement | PDF, 3 pages | View Download |
| 3 | Wreckage Diagram | PDF, 1 page | View Download |
| 4 | Maintenance Records - Aircraft Logbook | PDF, 7 pages | View Download |
| 5 | Maintenance Records - Engine Logbook | PDF, 22 pages | View Download |
| 6 | Maintenance Records - Inspection Record | PDF, 8 pages | View Download |
| 7 | Materials Laboratory Factual Report 15-070 | PDF, 14 pages | View Download |
| 8 | Conversation Record - Engine Manufacturer Rep | PDF, 1 page | View Download |
| 9 | Weather Documentation | PDF, 1 page | View Download |
The same docket at the NTSB · documents without a copy here are fetched from the NTSB when you open them.
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.