Wednesday, June 7, 2017

Cessna 180D, N6479X: Accident occurred May 03, 2016 at Naknek Airport (5NK), Bristol Bay Borough, Alaska

The National Transportation Safety Board did not travel to the scene of this accident.

Additional Participating Entity:
Federal Aviation Administration / Flight Standards District Office; Anchorage, Alaska

Investigation Docket - National Transportation Safety Board: https://dms.ntsb.gov/pubdms

Aviation Accident Factual Report - National Transportation Safety Board: https://app.ntsb.gov/pdf 

http://registry.faa.gov/N6479X

NTSB Identification: ANC16LA024 
14 CFR Part 91: General Aviation
Accident occurred Tuesday, May 03, 2016 in Naknek, AK
Aircraft: CESSNA 180, registration: N6479X
Injuries: 1 Uninjured.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

On May 3, 2016, about 1230 Alaska daylight time, a tailwheel-equipped Cessna 180 airplane, N6479X, sustained substantial damage following a separation of the left main wheel and axle from the landing gear strut during the landing rollout at the Naknek airport, Naknek, Alaska. The commercial pilot and sole occupant were not injured. The airplane was registered to Skol-Alaska, LLC and operated by the pilot under the provisions of 14 Code of Federal Regulations (CFR) Part 91 as a personal flight. Visual meteorological conditions prevailed at the time of the accident and a Federal Aviation Administration (FAA) visual flight rules (VFR) flight plan had been filed and activated.

During an interview with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) on May 3, 2016, the pilot stated that during the landing roll out, the left wheel axle fractured and separated from the airplane with the wheel attached. As the left landing gear leg dug into the runway surface, the airplane made a sudden left turn, and the left wing and left horizontal stabilizer struck the runway. The airplane sustained substantial damage to the left wing and left horizontal stabilizer. 

The fractured wheel axle was sent to the NTSB Materials Laboratory in Washington, D.C. for further examination. The fracture surface showed several areas of post-fracture damage. The undamaged portions of the fracture surface were optically, matte grey and highly textured consistent with a bending overstress fracture. Radial lines visible on the fracture indicated a wide area initiation at the outer diameter surface near the inboard end of the axle. High magnification optical examination of the fracture also revealed several small fatigue cracks within the crack origin area.

A Materials Laboratory Factual Report is located in the public docket for this accident.

The closest weather reporting facility is King Salmon Airport, King Salmon, Alaska, about 12 miles east of the accident site. At 1154, an aviation routine weather report (METAR) from the King Salmon Airport was reporting in part: wind from 080 degrees at 4 knots; sky condition, scattered at 2,700 feet AGL, broken at 5,000 feet AGL, broken at 7,500 feet AGL, broken at 20,000 AGL; visibility, 10 statute miles; temperature 52° F; dewpoint 36° F; barometric pressure 29.70 inHG.

NTSB Identification: ANC16LA024

14 CFR Part 91: General Aviation
Accident occurred Tuesday, May 03, 2016 in Naknek, AK
Aircraft: CESSNA 180, registration: N6479X
Injuries: 1 Uninjured.

This is preliminary information, subject to change, and may contain errors. Any errors in this report will be corrected when the final report has been completed. NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

On May 3, 2016, about 1230 Alaska daylight time, a tailwheel-equipped Cessna 180 airplane, N6479X, sustained substantial damage following a separation of the left main wheel and axle from the landing gear strut during the landing rollout at the Naknek Airport, Naknek, Alaska. The commercial pilot and sole occupant was not injured. The airplane was registered to Skol-Alaska, LLC, and operated by the pilot under the provisions of 14 Code of Federal Regulations (CFR) Part 91 as a personal flight. Visual meteorological conditions prevailed at the time of the accident, and a Federal Aviation Administration (FAA) visual flight rules (VFR) flight plan had been filed and activated.

During an interview with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) on May 3, 2016, the pilot stated that during the landing roll out, the left wheel axle fractured and separated from the airplane with the wheel attached. As the left landing gear leg dug into the runway surface, the airplane made a sudden left turn, and the left wing and left horizontal stabilizer struck the runway. The airplane sustained substantial damage to the left wing and left horizontal stabilizer. 

The closest weather reporting facility is King Salmon Airport, King Salmon, Alaska, about 12 miles east of the accident site. At 1154, an aviation routine weather report (METAR) from the King Salmon Airport was reporting in part: wind from 080 degrees at 4 knots; sky condition scattered at 2,700 feet agl, broken at 5,000 feet agl, broken at 7,500 feet agl, broken at 20,000 agl; visibility 10 statute miles; temperature 52 degrees F; dew point 36 degrees F; barometric pressure 29.70 inHg.

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