# NTSB CEN21LA450: Cessna 140, N84BC, Caddo Mills, TX, July 22, 2021 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 4 · Limited · Final report - Date: July 22, 2021, 09:45 local (14:45 UTC) - Place: Caddo Mills, TX - Coordinates: 33.0657, -96.2278 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=33.0657&lon=-96.2278&mi=10 - Phase of flight: [Unknown](https://openairdocs.org/ntsb-phases/990) (OpenAirDocs' grouping) - Defining event: [Unknown: Part(s) separation from AC](https://openairdocs.org/ntsb-events/338) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 4 - Basic report with no Prelim publish - NTSB office: Central Region - Parties: FAA - NTSB case key (mKey): 103955 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN21LA450 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/103955/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=103955 - Page: https://openairdocs.org/ntsb/CEN21LA450 ## Probable cause The missing vertical stabilizer hardware, which resulted in a severe uncommanded yawing motion that necessitated an emergency landing, during which the airplane nosed over and sustained substantial damage to the vertical stabilizer. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Empennage structure: vertical stab attach fitting](https://openairdocs.org/ntsb-findings/01035553): Aircraft › Aircraft structures · Failure (probable cause); cases with it: [Cessna 140, 1 case](https://openairdocs.org/ntsb-findings/01035553/cases.md?model=2071602), [All aircraft, 2 cases](https://openairdocs.org/ntsb-findings/01035553/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Unknown: Part(s) separation from AC](https://openairdocs.org/ntsb-events/338) (defining event); cases with it: [Cessna 140, 3 cases](https://openairdocs.org/ntsb-events/338/sequence.md?model=2071602), [All aircraft, 563 cases](https://openairdocs.org/ntsb-events/338/sequence.md) ## Analysis The flight instructor reported that while on downwind in the traffic pattern, the airplane began to yaw to the right. He immediately took control of the airplane from the student pilot and applied full left aileron and rudder, which reduced the yaw, however, the airplane still would not fly straight. He performed an emergency landing to a field, but shortly after touching down, the airplane nosed over, coming to rest inverted. The airplane sustained substantial damage to the vertical stabilizer and rudder. A postaccident inspection found that the forward vertical stabilizer attach bolt (P/N AN4-5A), nut (P/N AN365-428) and shim (P/N 0430010) were missing. (See figure 1) As a result of the missing hardware, the vertical stabilizer became unseated and bent aft in flight, which caused the uncommanded yawing motion. The hardware was not recovered. Figure 1. Fin assembly. The pilot reported that he was unaware of any recent maintenance in the affected area. ## Aircraft - Registration: [N84BC](https://openairdocs.org/aircraft/N84BC), registered now, S/N 10255, built 1946 (OpenAirDocs) - Reported make and model: CESSNA 140 - Registry model: [Cessna 140](https://openairdocs.org/model/cessna-140) (registry code 2071602) (OpenAirDocs) - Registry engine: [Continental C85 series](https://openairdocs.org/engine/continental-c85-series) (registry code 17008, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 10255 - Year built: 1946 - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Normal - Departed: 1F7, Dallas, TX - Airport: 7F3 ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 56; injuries: none; commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 2, with waivers/limitations; last flight review June 14, 2021; seat: left; restraint: lap only; flight hours: 5,200 total, 150 in this make and model, 250 in the last 90 days, 75 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 81 °F, dew point 72 °F - Altimeter: 30.15 inHg - Observed at: KGVT, 8 nm away - METAR: METAR KGVT 221440Z AUTO 00000KT 10SM CLR 27/22 A3015 RMK AO2 TSNO T02660225= ## 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 20210722011369A](https://openairdocs.org/incident/20210722011369A), Jul 22, 2021: Cessna 140, Caddo Mills, TX, Substantial damage. While on downwind for runway 18 at Caddo Mills municipal (7F3), pilot felt a "pop" with associated yaw to the right. Left rudder and left aileron were applied… ## Docket (3 files) The files NTSB released with the investigation on November 16, 2021, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=103955. 2.0 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 11 pages, 1.4 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12852731&FileExtension=pdf&FileName=Accident%20Reporting%20Form%206120_Redacted-Rel.pdf - Pilot's statement (item 2, PDF, 1 page, 123 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12853349&FileExtension=pdf&FileName=PIC%20Conversation%20Record-Rel.pdf - Photos (item 3, PDF, 2 pages, 489 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12853489&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.