Cessna 208 N336DN

Summary

On 15 September 2009 at about 18:35 local time, a Cessna 208 registered N336DN, operated by North American Flight Services Inc, was involved in an accident near Sheffield, Massachusetts, United States. 6 people were on board and nobody was injured. The aircraft was destroyed. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

15 September 2009 at 18:35

Classification

Accident

Location

Sheffield, Massachusetts, United States

Coordinates

42.0970, -73.3565

Aircraft

Cessna 208

Registration

N336DN

Category

Airplane

Engines

1

Operator

North American Flight Services Inc

Operating rule

Part 135: Air Taxi & Commuter

Phase of flight

Not recorded

Route

Farmingdale → Saratoga Spgs

Aircraft damage

Destroyed

Weather

VMC

Light

Day

NTSB number

ERA09LA523

Nobody was injured.

A total loss of engine power due to a failure of the 1st stage sun gear output splines for unknown reasons, which resulted in a power turbine overspeed condition, with subsequent blade distress/release.

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

Read the full NTSB narrative

The pilot and the five passengers, who were employees of an industrial services company, were returning from a job site with hazardous materials used for blasting operations. The airplane was in a climb, at an altitude of 8,500 feet, when it experienced a catastrophic engine failure. The pilot declared an emergency and subsequently performed a forced landing to a field. During the landing, the airplane's right wing struck a tree and separated. All occupants exited the airplane without injury; however, the airplane became fully engulfed in fire, which consumed the majority of the airplane. The airplane was equipped with a turbine engine that, at the time of the accident, had been operated for about 7,620 hours since new and 65 hours since it was overhauled about 19 months prior to the accident. Impact damage was observed to the interior of the engine exhaust duct. In addition, the exhaust duct contained portions of a fractured power turbine blade. Additional examination of the engine revealed damage consistent with a distressed 1st stage sun gear, and associated compressor turbine and power turbine damage. Examination of the sun gear teeth output splines revealed that they were too damaged to determine the cause of their deterioration. It was noted that the sun gear found on the accident engine was previously removed from another engine due to "spalled gear teeth" about 7 years prior to the accident. The condition of the sun gear when installed on the accident engine could not be determined.

Quoted verbatim from the NTSB record.