# NTSB ANC20LA100: Cessna 180, N926LL, Tok, AK, October 1, 2020 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 3 · Limited · Final report - Date: September 30, 2020, 19:40 local (Oct 1, 2020, 03:40 UTC) - Place: Tok, AK - Coordinates: 63.329514, -142.95368 - Nearby events: https://openairdocs.org/map.md?lat=63.3295&lon=-142.9537&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Defining event: [Landing-landing roll: Loss of control on ground](https://openairdocs.org/ntsb-events/230) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Alaska Regional Office - NTSB case key (mKey): 102108 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC20LA100 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/102108/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=102108 - Page: https://openairdocs.org/ntsb/ANC20LA100 ## Probable cause The mechanic’s failure to properly repair the tailwheel, which resulted in a malfunction of the tailwheel and a loss of directional control. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Landing gear system: nose/tail landing gear](https://openairdocs.org/ntsb-findings/01023220): Aircraft › Aircraft systems · Incorrect service/maintenance (probable cause); cases with it: [Cessna 180H, 2 cases](https://openairdocs.org/ntsb-findings/01023220/cases.md?model=2072618), [All aircraft, 185 cases](https://openairdocs.org/ntsb-findings/01023220/cases.md) - [Maintenance: repair](https://openairdocs.org/ntsb-findings/02062015): Personnel issues › Task performance · Maintenance personnel (probable cause); cases with it: [Cessna 180H, 1 case](https://openairdocs.org/ntsb-findings/02062015/cases.md?model=2072618), [All aircraft, 99 cases](https://openairdocs.org/ntsb-findings/02062015/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: Loss of control on ground](https://openairdocs.org/ntsb-events/230) (defining event); cases with it: [Cessna 180H, 31 cases](https://openairdocs.org/ntsb-events/230/sequence.md?model=2072618), [All aircraft, 4,585 cases](https://openairdocs.org/ntsb-events/230/sequence.md) ## Analysis The pilot stated that after landing, as the airplane decelerated and rudder effectiveness diminished, the airplane veered abruptly to the right. Left rudder was applied but was unsuccessful in controlling the airplane. The airplane exited the runway and the left main gear separated from the gear box resulting in substantial damage to the fuselage. A postaccident examination revealed excessive wear, damage, and a missing component inconsistent with proper tailwheel maintenance occurring the day before the accident. ## Factual narrative On September 30, 2020, about 1940 Alaska daylight time, a Cessna 180H airplane, N926LL, sustained substantial damage when it was involved in an accident near Tok Junction, Alaska. The pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot stated that she was landing her tailwheel-equipped airplane on an asphalt surfaced runway. After a normal touchdown in the three-point attitude, the airplane drifted to the left and right of the runway centerline but was corrected each time with the light application of the appropriate rudder pedal. As the airplane decelerated and rudder effectiveness diminished, the airplane veered abruptly to the right. Left rudder was applied but was unsuccessful in controlling the airplane. The airplane exited the runway, and the left main gear separated from the gear box, resulting in substantial damage to the fuselage. Aircraft maintenance records revealed that on September 29, the day before the accident, the tailwheel had been repaired and the tailwheel bearings replaced. A postaccident examination revealed that the tailwheel rotated freely to the right but was very stiff and difficult to rotate to the left. Disassembly of the tailwheel revealed that the steering arm inside radius (item #13 in figure 1 below) was heavily scored and worn. The compression spring (item #19 in figure 1 below) had sharp and damaged edges on the ends of the spring, and the spacer (item #20 or #21 in figure 1 below) was not present, which allowed for excessive movement of the spring in its assembly. Figure 1 - Scott 3400 series tailwheel parts illustration. ## Aircraft - Registration: [N926LL](https://openairdocs.org/deregistered/N926LL-2023-05-26), registration cancelled 2023-05-26, S/N 18051470, built 1964 (OpenAirDocs) - Reported make and model: CESSNA 180 (H) - Registry model: [Cessna 180H](https://openairdocs.org/model/cessna-180h) (registry code 2072618) (OpenAirDocs) - Registry engine: [Continental O-470 series](https://openairdocs.org/engine/continental-o-470-series) (registry code 17026, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 18051470 - Year built: 1964 - Airframe hours: 5471.1 - Engines: Continental O-470-R 230 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, August 28, 2020 - Departed: PAUO, Willow, AK - Destination: Same as departure - Airport: 6K8, Tok Junction Airport, runway 25, 2,509 × 50 ft, asphalt - Equipment: Electronic flight bag or handheld device, Satellite tracking device ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 43; injuries: none; commercial, private; airplane ratings: single-engine sea, single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, without waivers/limitations; last flight review April 4, 2020; seat: left; flight hours: 1,765 total, 264 in this make and model, 1,398 as pilot in command, 87 in the last 90 days, 34 in the last 30 days, 3 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 330° at 3 knots - Visibility: 10 statute miles - Temperature: 43 °F, dew point 30 °F - Altimeter: 29.67 inHg - Observed at: PAOR, 34 nm away - METAR: PAOR 010253Z AUTO 33003KT 10SM CLR 06/M01 A2967 RMK AO2 SLP067 T00611006 55002 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 20200930015269A](https://openairdocs.org/incident/20200930015269A), Sep 30, 2020: Cessna 180H, Tok, AK, Substantial damage. Pilot stated she did a normal 3 point landing. As she was slowing down she had difficulties keeping the aircraft straight. There was very little left rudder… ## Other investigations on N926LL (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 WPR22LA016](https://openairdocs.org/ntsb/WPR22LA016), Oct 12, 2021: Cessna 180H (N926LL), Kalispell, MT, substantial damage. Probable cause: The pilot’s failure to maintain directional control during landing, which resulted in a ground loop and a runway excursion. ## Docket (3 files) The files NTSB released with the investigation on January 26, 2022, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=102108. 6.8 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 9 pages, 4.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12507032&FileExtension=pdf&FileName=6120%20DMS_Redacted-Rel.pdf - Tailwheel examination summary (item 2, PDF, 6 pages, 1.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13156348&FileExtension=pdf&FileName=Tailwheel%20Examination%20Summary%20N926LL_Redacted-Rel.pdf - Photos (item 3, PDF, 5 pages, 837 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13156049&FileExtension=pdf&FileName=Photo%20Array-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.