# NTSB WPR21LA339: Cessna A185F, N185BB, Arlington, WA, September 8, 2021 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 3 · Limited · Final report - Date: September 8, 2021, 11:30 local (18:30 UTC) - Place: Arlington, WA · Airport - Coordinates: 48.16075, -122.15902 - Nearby events: https://openairdocs.org/map.md?lat=48.1608&lon=-122.1590&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: 3 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Western Pacific Region - Parties: Federal Aviation Administration - NTSB case key (mKey): 103832 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR21LA339 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/103832/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=103832 - Page: https://openairdocs.org/ntsb/WPR21LA339 ## Probable cause The fatigue fracture of the tailwheel fitting spring, which resulted in the loss of directional control during the landing roll. ## 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 · Fatigue/wear/corrosion (probable cause); cases with it: [Cessna A185F, 1 case](https://openairdocs.org/ntsb-findings/01023220/cases.md?model=2072821), [All aircraft, 185 cases](https://openairdocs.org/ntsb-findings/01023220/cases.md) - [Landing gear system: nose/tail landing gear](https://openairdocs.org/ntsb-findings/01023220): Aircraft › Aircraft systems · Failure (probable cause); cases with it: [Cessna A185F, 1 case](https://openairdocs.org/ntsb-findings/01023220/cases.md?model=2072821), [All aircraft, 185 cases](https://openairdocs.org/ntsb-findings/01023220/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 A185F, 75 cases](https://openairdocs.org/ntsb-events/230/sequence.md?model=2072821), [All aircraft, 4,585 cases](https://openairdocs.org/ntsb-events/230/sequence.md) ## Analysis The flight instructor of a tailwheel airplane was demonstrating a wheel landing to the pilot receiving instruction. The airplane touched down normally on its main landing gear, and, as the tailwheel touched down, the airplane veered to the right. The flight instructor attempted to correct back to the runway, but the airplane continued off the runway and ground looped to the right. The left wing and horizontal stabilizer sustained substantial damage. Examination of the airplane revealed the tailwheel fitting had separated near the weld gap between the fitting cross tube and the attachment brace. Metallurgical examination of the fracture surfaces identified corrosion pits where the fatigue cracks had initiated. The corrosion pits formed along the outer diameter surface of the tube within the gap against the brace, which created crevice corrosion. As a result of the crevice corrosion, the landing gear failed during the landing rollout, which caused the pilot to lose directional control of the airplane and subsequent ground loop. ## Factual narrative On September 8, 2021, about 1130 Pacific daylight time, a Cessna A185F, N185BB, was substantially damaged when it was involved in an accident near Arlington, Washington. The flight instructor, pilot receiving instruction, and passenger were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 instructional flight. The flight instructor of the tailwheel airplane reported that, after the pilot receiving instruction performed several landings, he assumed control of the airplane to demonstrate a wheel landing. During the landing roll to runway 16, as the tailwheel touched down, the airplane veered to the right. While attempting to correct with brake and rudder, the airplane exited the right side of the runway and ground looped to the right. The left wing and horizontal stabilizer struck the surface. Postaccident examination of the airplane revealed that the tailwheel fitting spring attachment was partially fractured and rotated about 90° from its normal position. The tailwheel fitting spring attachment was sent to National Transportation Safety Board Materials Laboratory, Washington, DC, for examination. The examination of the fracture surface revealed fatigue cracking that initiated at the fillet weld gap between the fitting cross tube and the attachment brace. The fatigue cracks initiated at corrosion pits that had formed along the outer diameter surface of the tube within the gap against the brace. These characteristics were consistent with crevice corrosion. A review of the airplane’s maintenance records revealed that, about a month prior to the accident flight, the tailwheel fitting spring attachment was removed, and new bushings and washers were replaced. The tailwheel fitting spring was then reinstalled with new hardware. The age of the tailwheel fitting spring attachment could not be determined. ## Aircraft - Registration: [N185BB](https://openairdocs.org/aircraft/N185BB), registered now, S/N 18503449, built 1977 (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-550 series](https://openairdocs.org/engine/continental-io-550-series) (registry code 17042, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 18503449 - Year built: 1977 - Airframe hours: 14781.2 - Engines: Continental IO-550-D15B 300 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Operator: Mission Aviation Training Academy - Registered owner: Higher Power Aviation Inc - Airworthiness certificate: Standard, Normal - Last inspection: Annual, July 23, 2021, 2.9 hours before - Destination: Same as departure - Airport: AWO, Arlington Muni, runway 16, 5,332 × 100 ft, asphalt - Equipment: ADS-B, Stall warning system ## Flight crew As NTSB recorded them. NTSB leaves out names. - Flight instructor; age 68; injuries: none; commercial, flight instructor; airplane ratings: single-engine sea, multi-engine land; instrument ratings: airplane; medical: class 2, with waivers/limitations; last flight review September 30, 2020; seat: right; restraint: 4-point; flight hours: 8,289 total, 401 in this make and model, 8,084 as pilot in command, 53 in the last 90 days, 19 in the last 30 days, 4 in the last 24 hours - Student pilot; age 27; injuries: none; commercial; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 2, without waivers/limitations; seat: left ## Weather - Conditions: Visual (VMC), Day - Wind: 170° at 8 knots - Visibility: 10 statute miles - Temperature: 73 °F, dew point 52 °F - Altimeter: 30.03 inHg - Observed at: KAWO - METAR: KAWO 081856Z AUTO 17008KT 10SM SCT095 23/11 A3003 RMK AO2 SLP171 T02330111 ## 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 20210908015479A](https://openairdocs.org/incident/20210908015479A), Sep 8, 2021: Cessna A185F, Arlington, WA, Substantial damage. While executing a wheel landing on rwy 29 at awo, upon touch down the aircraft began a gentle drift to the right which could not be corrected with left brake… ## Docket (7 files) The files NTSB released with the investigation on March 1, 2023, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=103832. 6.9 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 9 pages, 1.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12809538&FileExtension=pdf&FileName=6120%20Pilot%20Aircraft%20Accident%20Report_Redacted-Rel.pdf - Record of phone conversation (CFI) (item 2, PDF, 1 page, 168 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14152970&FileExtension=pdf&FileName=Record%20of%20phone%20conversation%20(CFI)-Rel.pdf - Materials laboratory factual report (item 3, PDF, 19 pages, 25 photos, 3.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13994008&FileExtension=pdf&FileName=22-044%20-%20Materials%20Lab%20Factual%20Report%20(WPR21LA339)-Rel.pdf - Record of e-mail correspondence (A&P) (item 4, PDF, 1 page, 163 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14058336&FileExtension=pdf&FileName=Record%20of%20e-mail%20correspondence%20(A%26P)-Rel.pdf - Release of aircraft wreckage, NTSB form 6120.15 (item 5, PDF, 1 page, 478 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14151205&FileExtension=pdf&FileName=Wreckage%20Release_Redacted-Rel.pdf - Evidence control forms (item 6, PDF, 3 pages, 422 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14150422&FileExtension=pdf&FileName=Evidence%20Control%20Forms_Redacted-Rel.pdf - Photo array (item 7, PDF, 3 pages, 173 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14153135&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.