# NTSB ANC16LA046: Cessna A185, N85CF, Illiamna, AK, July 19, 2016 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: July 19, 2016, 10:30 local (18:30 UTC) - Place: Illiamna, AK - Coordinates: 59.945835, -156.359451 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=59.9458&lon=-156.3595&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Defining event: [Landing-landing roll: Part(s) separation from AC](https://openairdocs.org/ntsb-events/338) - Highest injury: No injuries - Injuries: 4 uninjured - Status: Completed, report July 26, 2017 - Report: Approved by Office Director - NTSB office: Alaska Regional Office - Parties: FAA Denali CMO-07, FAA Denali CMO - NTSB case key (mKey): 93642 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC16LA046 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/93642/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=93642 - Page: https://openairdocs.org/ntsb/ANC16LA046 ## Probable cause The overstress fracture of the left main landing (MLG) gear axle attachment bolts and the subsequent separation of the left MLG wheel, which resulted in the pilot’s inability to control the airplane. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Landing gear system: main gear strut/axle/truck](https://openairdocs.org/ntsb-findings/01023213): Aircraft › Aircraft systems · Capability exceeded (probable cause); cases with it: [Cessna A185E, 1 case](https://openairdocs.org/ntsb-findings/01023213/cases.md?model=2072818), [All aircraft, 86 cases](https://openairdocs.org/ntsb-findings/01023213/cases.md) - [Landing gear system: main gear strut/axle/truck](https://openairdocs.org/ntsb-findings/01023213): Aircraft › Aircraft systems · Failure (probable cause); cases with it: [Cessna A185E, 1 case](https://openairdocs.org/ntsb-findings/01023213/cases.md?model=2072818), [All aircraft, 86 cases](https://openairdocs.org/ntsb-findings/01023213/cases.md) - [Performance/control parameters: directional control](https://openairdocs.org/ntsb-findings/01062020): Aircraft › Aircraft oper/perf/capability · Attain/maintain not possible (probable cause); cases with it: [Cessna A185E, 18 cases](https://openairdocs.org/ntsb-findings/01062020/cases.md?model=2072818), [All aircraft, 3,958 cases](https://openairdocs.org/ntsb-findings/01062020/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Landing-landing roll: Part(s) separation from AC](https://openairdocs.org/ntsb-events/338) (defining event); cases with it: [Cessna A185E, 1 case](https://openairdocs.org/ntsb-events/338/sequence.md?model=2072818), [All aircraft, 563 cases](https://openairdocs.org/ntsb-events/338/sequence.md) - [Landing-landing roll: Loss of control on ground](https://openairdocs.org/ntsb-events/230); cases with it: [Cessna A185E, 19 cases](https://openairdocs.org/ntsb-events/230/sequence.md?model=2072818), [All aircraft, 4,585 cases](https://openairdocs.org/ntsb-events/230/sequence.md) ## Analysis The commercial pilot reported that he made a normal approach and landing to an unimproved landing strip and that the left main landing gear (MLG) wheel assembly separated from the landing gear leg at the axle bolts during rollout. The gear leg then dug into the gravel landing surface, which resulted in a sudden left turn, ground loop, and subsequent substantial damage to the left wing, left aileron, and elevator. The pilot and the passenger stated that it did not feel as if the airplane hit anything during the landing rollout. The pilot also stated that the initiating event may have been a crosswind landing on a hard-surfaced runway with large tundra tires earlier in the week, during which he inadvertently "put a side load on the landing gear." Postaccident examination of the left MLG axle assembly and bolts revealed that the left axle had separated from the landing gear leg due to a rearward overload event. The initial separation was due to the shearing of the forward bolt threads by tensile forces on the bolts, which was followed by the bending deformation of the aft bolts, consistent with a fore-to-aft overload. ## Factual narrative On July 19, 2016, about 1030 Alaska daylight time, a tailwheel-equipped Cessna 185 airplane, N85CF, sustained substantial damage following a separation of the left main wheel and axle from the landing gear leg during the landing rollout at an unimproved landing strip about 20 miles northwest of Illiamna, Alaska. The commercial pilot, and three passengers were not injured. The airplane was registered to and operated by the pilot, as a visual flight rules (VFR) business flight, under the provisions of 14 Code of Federal Regulations (CFR) Part 91. Visual meteorological conditions prevailed at the time of the accident and no flight plan was filed. During an interview with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) on July 20, 2016, the pilot stated that after a normal landing to a flat, level ridgeline, the left wheel and axle separated from the landing gear leg during the landing rollout. The gear leg then dug into the gravel landing surface which resulted in a sudden left turn and subsequent ground loop. The left wing, left aileron and elevator struck the ground and sustained substantial damage. The left wheel assembly came to rest about 25 feet from the airplane. A passenger of the accident flight stated during an interview that the she did not feel the landing was hard and did not feel the airplane hit anything on the landing roll out. The pilot stated on NTSB Form 6120.1, Pilot/Operator Aircraft Accident/Incident Report, that the landing was normal and he did not feel the aircraft hit anything. He stated that, while on large tundra tires, he inadvertently put a side load on the landing gear earlier in the week during a landing on a hard-surfaced runway with a strong crosswind. An NTSB metallurgist conducted an examination of the left axle connecting bolts. The bolts were identified as heavy duty and appropriate for installation per the Cessna 185 Illustrated Parts Catalog. Magnified examinations of the separations revealed fracture features and deformation patterns consistent with bending overstress separations. No indications of preexisting cracking or corrosion were visible. (Refer to the Materials Laboratory Factual Report in the public docket for further information regarding the fractured components.) The closest weather reporting facility is Illiamna Airport, Illiamna, Alaska, about 20 miles southeast of the accident site. At 0953, an Aviation Routine Weather Report (METAR) from the Illiamna Airport was reporting in part: wind from 320° at 10 knots gusting to 18 knots; sky condition, clear; visibility, 10 statute miles; temperature 63° F; dew point 48° F; barometric pressure 30.19 inHg. ## Aircraft - Registration: [N85CF](https://openairdocs.org/aircraft/N85CF), registered now, S/N 18501904, built 1971 (OpenAirDocs) - Reported make and model: CESSNA A185 (E) - Registry model: [Cessna A185E](https://openairdocs.org/model/cessna-a185e) (registry code 2072818) (OpenAirDocs) - Category: Airplane - Serial number: 18501904 - Year built: 1971 - Engines: Continental IO-520D 300 horsepower reciprocating - Damage: Substantial damage - Flight: Business, Part 91 - Airworthiness certificate: Standard, Normal - Departed: PAIL, ILIAMNA, AK - Destination: NONE, Iliamna, AK - Flight plan: Company VFR - Equipment: Handheld GPS, Stall warning system ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 59; injuries: none; commercial; airplane ratings: multi-engine land, single-engine sea, single-engine land; instrument ratings: airplane; medical: class 3, with waivers/limitations; last flight review July 2, 2015; seat: left; restraint: 3-point; flight hours: 14,000 total, 4,000 in this make and model, 35 in the last 90 days, 20 in the last 30 days, 4 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 320° at 10 knots, gusting 18 - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 63 °F, dew point 48 °F - Altimeter: 30.19 inHg - Observed at: PAIL, 45 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 20160719022989A](https://openairdocs.org/incident/20160719022989A), Jul 19, 2016: Cessna A185E, Iliamna, AK, Substantial damage. On landing at a remote gravel landing strip, the aircraft sustained substantial damage to the propeller, left wing, left horizontal stabilizer and left main… ## Other investigations on N85CF (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 ANC98LA082](https://openairdocs.org/ntsb/ANC98LA082), Jun 20, 1998: Cessna 185E (N85CF), Anchorage, AK, substantial damage. Probable cause: The rotation/slippage of the right main tire on the wheel rim, resulting in shearing of the tire tube valve stem, and subsequent tire deflation. Factors in the accident were oversize, tundra tires… ## Docket (5 files) The files NTSB released with the investigation on June 5, 2017, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=93642. 1.7 MB in all. - Materials Laboratory Factual Report 16-067 (item 1, .PDF, 2 photos, 200 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40452834&FileExtension=.PDF&FileName=Materials%20Laboratory%20Factual%20Report%2016-067-Master.PDF - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 2, .PDF, 827 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40452835&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Record of Conversation (Pilot) (item 3, .PDF, 56 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40452836&FileExtension=.PDF&FileName=Record%20of%20Conversation%20(Pilot)-Master.PDF - Record of Conversation (Passenger) (item 4, .PDF, 55 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40452837&FileExtension=.PDF&FileName=Record%20of%20Conversation%20(Passenger)-Master.PDF - Photos (item 5, .PDF, 3 photos, 542 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40452838&FileExtension=.PDF&FileName=Photos-Master.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.