ANC13LA012

Shortly after the scheduled commuter flight departed with the second-in-command (SIC) at the controls, the engine "coughed," started vibrating, and lost power. The SIC attempted to restart the engine, but was unsuccessful. Subsequently, the pilot-in-command assumed control of the airplane and landed on a frozen bay, which resulted in substantial damage to the airplane's right wing and fuselage. A postaccident examination of the airplane's engine revealed that one of the first-stage compressor blades had fractured due to fatigue cracking. The source of the fatigue crack could not be determined due to secondary damage sustained to the fracture surface.

On December 3, 2012, about 1050 Alaska standard time, a Cessna 208B airplane, N169LJ, sustained substantial damage during a forced landing shortly after takeoff from the Mekoryuk Airport, Mekoryuk, Alaska. Of the nine people aboard, the two pilots and six passengers were not injured, and one passenger sustained minor injuries. The airplane was being operated as Flight 140, by Hageland Aviation Services, Inc., dba ERA Alaska, Anchorage, Alaska, as a visual flight rules (VFR) scheduled commuter flight under the provisions of 14 Code of Federal Regulations (CFR) Part 135. Visual meteorological conditions prevailed, and company flight following procedures were in effect. The flight originated at the Mekoryuk Airport about 1045, and was destined for Bethel, Alaska.In a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), the pilot-in-command (PIC) stated that the second-in-command (SIC) was the flying pilot for the flight to Bethel. He said that the takeoff and initial climb were normal, but shortly after passing 1,000 feet, the engine "coughed," started vibrating, and lost power. An attempt to restart the engine was not successful. The PIC assumed control of the airplane, and landed on a frozen bay approximately 5 miles northeast of the Mekoryuk Airport. Witnesses at the airport observed the airplane descending, and responded with snow machines, and all-terrain vehicles to transport the airplane's occupants back to Mekoryuk. During the forced landing the airplane sustained substantial damage to the fuselage and right wing. The airplane was equipped with a Pratt & Whitney PT6A-114A turbine engine. A postaccident engine examination, performed at the facilities of Pratt & Whitney Canada, St. Hubert, Quebec, Canada, and under the direction of a senior NTSB powerplants investigator, revealed that a blade on the first stage compressor rotor failed as a result of a fatigue fracture. The fatigue crack initiated from the leading edge area and then propagated towards the trailing edge, and at mid-chord, the blade released by tensile overload. The initiation of the fracture could not be determined because of secondary damage to the fracture surface. A copy of the Safety Board powerplants investigator's report is included in the public docket for this incident. During the last engine overhaul, 5 first stage compressor blades were replaced with new blades. The blade that failed during the accident flight was one of the five replaced blades based on the batch numbers recorded on the blades.