# NTSB ANC25LA059: Cessna 170B, N2655D, Denali Park, AK, June 25, 2025 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 4 · Limited · Final report - Date: June 24, 2025, 18:00 local (Jun 25, 2025, 02:00 UTC) - Place: Denali Park, AK - Coordinates: 63.22338, -150.94702 - Nearby events: https://openairdocs.org/map.md?lat=63.2234&lon=-150.9470&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Defining event: [Landing-landing roll: Sys/Comp malf/fail (non-power)](https://openairdocs.org/ntsb-events/330) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report January 9, 2026 - Report: Approved by Office Director - Investigation class: Class 4 - Basic report with no Prelim publish - NTSB office: Alaska Regional Office - Parties: FAA - FSDO - NTSB case key (mKey): 200423 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC25LA059 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/200423/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=200423 - Page: https://openairdocs.org/ntsb/ANC25LA059 ## Probable cause The failure of the left main landing gear spring due to a fatigue fracture during landing on uneven terrain. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Landing gear system: main landing gear](https://openairdocs.org/ntsb-findings/01023210): Aircraft › Aircraft systems · Failure (probable cause); cases with it: [Cessna 170B, 2 cases](https://openairdocs.org/ntsb-findings/01023210/cases.md?model=2072306), [All aircraft, 241 cases](https://openairdocs.org/ntsb-findings/01023210/cases.md) - [Landing gear system: main landing gear](https://openairdocs.org/ntsb-findings/01023210): Aircraft › Aircraft systems · Fatigue/wear/corrosion (probable cause); cases with it: [Cessna 170B, 2 cases](https://openairdocs.org/ntsb-findings/01023210/cases.md?model=2072306), [All aircraft, 241 cases](https://openairdocs.org/ntsb-findings/01023210/cases.md) - [Maintenance: scheduled/routine maintenance](https://openairdocs.org/ntsb-findings/02062010): Personnel issues › Task performance · Maintenance personnel; cases with it: [Cessna 170B, 1 case](https://openairdocs.org/ntsb-findings/02062010/cases.md?model=2072306), [All aircraft, 320 cases](https://openairdocs.org/ntsb-findings/02062010/cases.md) - [Use of equip/info: aircraft control](https://openairdocs.org/ntsb-findings/02063040): Personnel issues › Task performance · Pilot; cases with it: [Cessna 170B, 91 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md?model=2072306), [All aircraft, 9,295 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md) - [Info processing/decision: decision making/judgment](https://openairdocs.org/ntsb-findings/02041520): Personnel issues › Action/decision · Pilot; cases with it: [Cessna 170B, 15 cases](https://openairdocs.org/ntsb-findings/02041520/cases.md?model=2072306), [All aircraft, 3,098 cases](https://openairdocs.org/ntsb-findings/02041520/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: Sys/Comp malf/fail (non-power)](https://openairdocs.org/ntsb-events/330) (defining event); cases with it: [Cessna 170B, 3 cases](https://openairdocs.org/ntsb-events/330/sequence.md?model=2072306), [All aircraft, 994 cases](https://openairdocs.org/ntsb-events/330/sequence.md) ## Analysis The pilot reported that, during the landing roll in a tailwheel-equipped airplane on a remote airstrip, he encountered a depression in the landing surface, resulting in the separation of the left main wheel. The left main landing gear leg subsequently dug into the ground and folded back against the fuselage, which caused substantial damage to the fuselage near the main landing gear attach points. After exiting the airplane, the pilot observed that the left main gear leg had fractured above the axle bolts, and the tire, axle, and lower portion of the main landing gear spring had separated from the airplane. The pilot reported that there were no preaccident mechanical failures or malfunctions with the airplane that would have precluded normal operation. Photos of the fracture surfaces from the main landing gear spring were examined by the NTSB Materials Laboratory. The features observed were consistent with a fatigue fracture and corrosion. It is likely that a fatigue crack initiated due to corrosion damage at the fracture origin. ## Aircraft - Registration: [N2655D](https://openairdocs.org/aircraft/N2655D), registered now, S/N 20807, built 1956 (OpenAirDocs) - Reported make and model: CESSNA 170B - Registry model: [Cessna 170B](https://openairdocs.org/model/cessna-170b) (registry code 2072306) (OpenAirDocs) - Registry engine: [Franklin 6A-350SER](https://openairdocs.org/engine/franklin-6a-350ser) (registry code 27023, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 20807 - Year built: 1956 - Airframe hours: 5487.5 - Engines: Franklin 6A-350-C2 220 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, January 18, 2025, 64 hours before - Departed: 5Z5, Kantishna, AK - Destination: Same as departure - Flight plan: Company VFR - Airport: NONE, Backcountry Airstrip - Equipment: Stall warning system ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 36; injuries: none; commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, without waivers/limitations; last flight review June 8, 2025; seat: left; restraint: 3-point; flight hours: 3,366.9 total, 478 in this make and model, 3,319 as pilot in command, 255 in the last 90 days, 80.6 in the last 30 days, 3 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 32 °F, dew point 32 °F - Altimeter: 29.68 inHg - Observed at: AIN, 62 nm away - METAR: PAIN 250156Z AUTO VRB03KT 10SM CLR A2968 RMK AO2 SLPNO FZRANO TSNO $ ## 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 20250624009889A](https://openairdocs.org/incident/20250624009889A), Jun 24, 2025: Cessna 170B, Kantishna, AK, Substantial damage. Aircraft landed on unapproved airstrip. During rollout l/h tire hit rut on surface of landing location and departed aircraft. Aircraft continued an additional… ## Docket (3 files) The files NTSB released with the investigation on January 9, 2026, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=200423. 2.3 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 10 pages, 1.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=19035229&FileExtension=pdf&FileName=ANC25LA059%206120_Redacted-Rel.pdf - Materials lab fracture assessment (item 2, PDF, 2 pages, 285 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=19036095&FileExtension=pdf&FileName=ANC25LA059%20Materials%20Lab%20Fracture%20Assessment-Rel.pdf - Photos (item 3, PDF, 4 pages, 308 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=19036617&FileExtension=pdf&FileName=ANC25LA059%20Photos-Rel.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.