# NTSB CEN18LA164: Beech 1900C, N172GA, Sioux Falls, SD, April 30, 2018 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: April 29, 2018, 22:30 local (Apr 30, 2018, 03:30 UTC) - Place: Sioux Falls, SD - Coordinates: 43.581943, -96.741943 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=43.5819&lon=-96.7419&mi=10 - Phase of flight: [Taxi](https://openairdocs.org/ntsb-phases/250) (OpenAirDocs' grouping) - Defining event: [Taxi: Sys/Comp malf/fail (non-power)](https://openairdocs.org/ntsb-events/330) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report May 29, 2019 - Report: Approved by Office Director - NTSB office: Central Region - Parties: FAA Flight Standards District Office - NTSB case key (mKey): 97218 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN18LA164 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/97218/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=97218 - Page: https://openairdocs.org/ntsb/CEN18LA164 ## Probable cause Failure of the right main landing gear drag brace bolt for reasons that could not be determined based on the available information. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Landing gear system: main landing gear attach sec](https://openairdocs.org/ntsb-findings/01023211): Aircraft › Aircraft systems · Failure (probable cause); cases with it: [Beech 1900C, 1 case](https://openairdocs.org/ntsb-findings/01023211/cases.md?model=1154161), [All aircraft, 66 cases](https://openairdocs.org/ntsb-findings/01023211/cases.md) - [Wing structure: spar (on wing)](https://openairdocs.org/ntsb-findings/01035711): Aircraft › Aircraft structures · Fatigue/wear/corrosion; cases with it: [Beech 1900C, 1 case](https://openairdocs.org/ntsb-findings/01035711/cases.md?model=1154161), [All aircraft, 43 cases](https://openairdocs.org/ntsb-findings/01035711/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Taxi: Sys/Comp malf/fail (non-power)](https://openairdocs.org/ntsb-events/330) (defining event); cases with it: [Beech 1900C, 2 cases](https://openairdocs.org/ntsb-events/330/sequence.md?model=1154161), [All aircraft, 994 cases](https://openairdocs.org/ntsb-events/330/sequence.md) - [Taxi: Landing gear collapse](https://openairdocs.org/ntsb-events/094); cases with it: [Beech 1900C, 2 cases](https://openairdocs.org/ntsb-events/094/sequence.md?model=1154161), [All aircraft, 1,787 cases](https://openairdocs.org/ntsb-events/094/sequence.md) ## Analysis As the twin-engine, turbopropeller-equipped airplane started to taxi for takeoff, the right main landing gear collapsed, deforming the aft center wing lower spar cap. A postaccident examination of the airplane revealed that the right main landing gear drag brace bolt failed at the wing forward attach point. As the airplane moved forward, the strut pivoted aft, collapsing the landing gear. The drag brace bolt was not retained, and the reason for its failure could not be determined based on the available information. ## Factual narrative On April 29, 2018, about 2230 central daylight time, a Beech 1900C, N172GA, was substantially damaged when the right main landing gear collapsed as the airplane started to taxi for takeoff at Joe Foss Field Airport (FSD), Sioux Falls, South Dakota. The airline transport pilot was not injured. The airplane was registered to and operated by Alpine Aviation, doing business as Alpine Air Express, under the provisions of Title 14 Code of Federal Regulations Part 135 as a non-scheduled domestic cargo flight. Visual meteorological conditions prevailed at the airport at the time of the accident, and an instrument flight rules flight plan had been filed. The flight was originating from FSD, and was destined for Rapid City Regional Airport (RAP), Rapid City, South Dakota. According to Federal Aviation Administration (FAA) inspectors, the airplane had just moved forward to taxi for takeoff when the right main landing gear collapsed. A postaccident examination of the airplane revealed the right main landing gear drag brace bolt failed at the wing forward attach point. The drag brace bolt was not retained for further examination. The strut pivoted aft when the airplane moved forward, and the landing gear collapsed. The aft center wing lower spar cap was dented and deformed up to 0.090". Further examination found pitting corrosion on the spar cap. ## Aircraft - Registration: [N172GA](https://openairdocs.org/aircraft/N172GA), registered now, S/N UB-11 (OpenAirDocs) - Reported make and model: BEECH 1900C - Registry model: [Beech 1900C](https://openairdocs.org/model/beech-1900c) (registry code 1154161) (OpenAirDocs) - Category: Airplane - Serial number: UB-11 - Year built: 1982 - Airframe hours: 41851 - Engines: Pratt & Whitney PT6A-65B 1100 horsepower turbo prop; Pratt & Whitney PT6A-65B 1100 horsepower turbo prop - Damage: Substantial damage - Flight: Part 135 - Operator: Alpine Aviation, Inc., doing business as Alpine Air Express - Registered owner: Alpine Aviation, Inc. - Airworthiness certificate: Standard, Normal - Last inspection: AAIP, March 10, 2018, 117 hours before - Departed: FSD, Sioux Falls, SD - Destination: RAP, Rapid City, SD - Flight plan: IFR - Airport: FSD, Joe Foss Field - Equipment: Stall warning system, Auto-pilot ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 57; injuries: none; airline transport, commercial, flight instructor; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 2, with waivers/limitations; last flight review November 28, 2017; seat: left; flight hours: 13,968 total, 1,000 in this make and model, 8,000 as pilot in command, 133 in the last 90 days, 50 in the last 30 days, 3 in the last 24 hours ## Weather - Conditions: Visual (VMC), Night - Wind: 160° at 15 knots - Visibility: 10 statute miles - Lowest ceiling: 10,000 ft broken - Temperature: 68 °F, dew point 45 °F - Altimeter: 29.79 inHg - Observed at: KFSD ## 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 20180429014919A](https://openairdocs.org/incident/20180429014919A), Apr 29, 2018: Beech 1900C, Sioux Falls, SD, Substantial damage. On may 6, 2018 at 2230 at Sioux Falls, SD airport (kfsd) the pilot started to taxi Beech 1900C, tail # N172GA when the right MLG collapsed. He had taxied about… ## Docket (3 files) The files NTSB released with the investigation on July 31, 2018, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=97218. 1.5 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 1.4 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40465547&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - E-mail from FAA Inspector (item 2, .PDF, 67 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40465548&FileExtension=.PDF&FileName=E-mail%20from%20FAA%20Inspector-Master.PDF - Factual Narrative Changes (item 3, .PDF, 44 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40472907&FileExtension=.PDF&FileName=Factual%20Narrative%20Changes-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.