# NTSB ANC13LA032: Cessna A185F, N185FK, Talkeetna, AK, March 8, 2013 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: March 8, 2013, 13:30 local (17:30 UTC) - Place: Talkeetna, AK - Coordinates: 62.856945, -150.70195 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=62.8569&lon=-150.7020&mi=10 - Phase of flight: [Taxi](https://openairdocs.org/ntsb-phases/250) (OpenAirDocs' grouping) - Defining event: [Taxi: Sys/Comp malf/fail (non-power)](https://openairdocs.org/ntsb-events/330) - Highest injury: No injuries - Injuries: 4 uninjured - Status: Completed, report December 11, 2013 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - Parties: Federal Aviation Administration - NTSB case key (mKey): 86455 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC13LA032 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/86455/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=86455 - Page: https://openairdocs.org/ntsb/ANC13LA032 ## Probable cause The overstress fracture and failure of the right wheel/ski arm while taxiing in snow and water-overflow terrain conditions, which resulted in a noseover. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Landing gear system: wheel/ski/float](https://openairdocs.org/ntsb-findings/01023246): Aircraft › Aircraft systems · Failure (probable cause) - [Runway/land/takeoff/taxi surface: snow/slush/ice covered surface](https://openairdocs.org/ntsb-findings/03023015): Environmental issues › Physical environment · Contributed to outcome ## Analysis The pilot and three passengers were on an air tour flight in a wheel/ski-equipped airplane. The pilot reported that, after landing on a frozen, snow-covered lake and while taxiing, he felt the weight of the airplane transfer to the right wheel/ski as he initiated a left turn. He stated that, during the turn, the airplane’s wheel/skis began to sink into the soft snow and that the airplane subsequently nosed over, sustaining substantial damage to the wings, rudder, and vertical stabilizer. After the accident, the pilot reported seeing water overflow in the ski tracks of the airplane, which can rapidly decelerate the airplane during taxi. A postaccident examination revealed that the ski arm assembly on the right wheel/ski had separated at the weld area. Magnified optical examination of the fracture surfaces revealed features consistent with overstress separations of the welds. No indication of preexisting cracking, such as fatigue or corrosion, was noted. ## Factual narrative On March 8, 2013, about 1330 Alaska standard time, a wheel/ski-equipped Cessna 185 airplane, N185FK, sustained substantial damage while taxiing on a remote, frozen, snow-covered lake near Talkeetna, Alaska. The certificated commercial pilot and three passengers were not injured. The airplane was registered to and operated by Talkeetna Air Taxi, under the provisions of Title 14 Code of Federal regulations Part 135, as a visual flight rules (VFR) sightseeing flight. Visual meteorological conditions prevailed, and a VFR flight plan had been filed. During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) on March 8, the pilot stated he departed the Talkeetna Airport on a scenic flight tour, which included an off-airport landing on skis. After landing, while taxiing in a left turn on the frozen, snow-covered lake, he felt the weight of the airplane transfer to the right ski. He said that during the turn, the airplane’s wheel/skis began to sink into the soft snow, and it subsequently nosed over, sustaining substantial damage to the wings, rudder and vertical stabilizer. After exiting the airplane, the pilot discovered water overflow in the ski tracks. In a written statement provided to the NTSB IIC, a passenger that was seated in the right front seat reported that the touchdown was soft with plenty of space for a long gentle rollout. At low speed, the pilot attempted to make a 180 degree turn to the left, and just after initiating the turn, the right ski began sinking in the soft snow, causing the aircraft to pitch down and roll to the right. The pilot attempted to prevent the nose down by pulling aft on the control yoke and retarding the throttle, but the airplane continued to nose over coming to rest inverted. A postaccident examination, by the operator, revealed that the ski arm on the right hand ski separated at the weld. The ski arm was sent to the NTSB’s Materials Laboratory in Washington, D.C. for examination. A Senior Safety Board Metallurgist reported that magnified optical examination of the fractured surfaces revealed features consistent with overstress separations of the welds. The examinations uncovered small amounts of gas porosity in the fractured angled tube weld, but no indications of corrosion or preexisting cracking in either separation. Details in the weld fractures were consistent with an inboard to outboard side load applied to the cross tube of the ski arm. (A synopsis of the NTSB Metallurgist's case review is included in the public docket for this accident.) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Taxi: Sys/Comp malf/fail (non-power)](https://openairdocs.org/ntsb-events/330) (defining event) - [Taxi: Nose over/nose down](https://openairdocs.org/ntsb-events/096) ## Aircraft - Registration: [N185FK](https://openairdocs.org/aircraft/N185FK), registered now, S/N 18502513, built 1974 (OpenAirDocs) - Reported make and model: CESSNA A185F - Registry model: [Cessna A185F](https://openairdocs.org/model/cessna-a185f) (registry code 2072821) (OpenAirDocs) - Registry engine: [Continental IO-520 series](https://openairdocs.org/engine/continental-io-520-series) (registry code 17032, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 18502513 - Airframe hours: 11283 - Engines: CONT MOTOR IO 550 SERIES 300 horsepower reciprocating - Damage: Substantial damage - Flight: Part 135 - Operator: Talkeetna Air Taxi Inc - Registered owner: Talkeetna Air Taxi Inc - Airworthiness certificate: Standard, Normal - Last inspection: AAIP, November 8, 2012 - Departed: PATK, Talkeetna, AK - Destination: Talkeetna, AK - Flight plan: Unknown ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 46; injuries: none; flight instructor, commercial, private; airplane ratings: single-engine sea, single-engine land, multi-engine land; instrument ratings: airplane; medical: class 2, without waivers/limitations; last flight review April 30, 2012; seat: left; flight hours: 11,850 total, 6,900 in this make and model, 11,850 as pilot in command, 77 in the last 90 days, 28 in the last 30 days, 3 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 10 statute miles - Lowest ceiling: 5,500 ft overcast - Temperature: 37 °F, dew point 21 °F - Altimeter: 29.62 inHg - Observed at: PATK, 42 nm away ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 20130308004559A](https://openairdocs.org/incident/20130308004559A), Mar 8, 2013: Cessna A185F, Talkeetna, AK, Substantial damage. The pilot stated he was landing at back side lake for tourist. He circled the lake then landed to the west. After landing the snow felt very heavy, it required… ## Other investigations on N185FK (1) From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. - [NTSB ANC94LA016](https://openairdocs.org/ntsb/ANC94LA016), Nov 8, 1993: Cessna A185F (N185FK), Chefornak, AK, substantial damage. Probable cause: THE FAILURE OF THE PILOT-IN-COMMAND TO ADEQUATELY COMPENSATE FOR THE GUSTY CROSS WIND CONDITION. A FACTOR IN THE ACCIDENT WAS THE WIND GUST. ## Docket (5 files) The files NTSB released with the investigation on July 31, 2013, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=86455. 2.0 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 1.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40391651&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Materials Laboratory Synopsis with Photo (item 2, .PDF, 1 photo, 198 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40397784&FileExtension=.PDF&FileName=Materials%20Laboratory%20Synopsis%20with%20Photo-Master.PDF - Evidence Control Form (item 3, .PDF, 65 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40399839&FileExtension=.PDF&FileName=Evidence%20Control%20Form-Redacted.PDF - Retention / Release of Wreckage Form (item 4, .PDF, 118 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40398089&FileExtension=.PDF&FileName=Retention%20%2F%20Release%20of%20Wreckage%20Form-Redacted.PDF - Retention / Release of Wreckage Form (item 5, .PDF, 254 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40398090&FileExtension=.PDF&FileName=Retention%20%2F%20Release%20of%20Wreckage%20Form-Redacted.PDF From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.