# NTSB CEN11IA615: Bombardier CL-600-2B19, N875AS, Baton Rouge, LA, September 1, 2011

- Type: NTSB incident investigation
- Classification: Incident · No injuries · Incident investigation · Final report
- Date: September 1, 2011, 17:25 local (22:25 UTC)
- Place: Baton Rouge, LA
- Coordinates: 30.532777, -91.149719 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=30.5328&lon=-91.1497&mi=10
- Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping)
- Defining event: [Landing: Landing gear not configured](https://openairdocs.org/ntsb-events/095)
- Highest injury: No injuries
- Injuries: 53 uninjured
- Status: Completed, report January 30, 2014
- Report: Approved by Office Director
- NTSB office: Central Region
- Parties: Federal Aviation Administration, Atlantic Southeast Airlines
- NTSB case key (mKey): 81683
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN11IA615
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/81683/pdf
- NTSB docket: https://data.ntsb.gov/Docket?ProjectID=81683
- Page: https://openairdocs.org/ntsb/CEN11IA615

## Probable cause

The improperly installed upper attachment bolt in the left main landing gear uplock assembly, which led to the failure of the left main landing gear to extend before landing. Contributing to the accident was maintenance personnel's lack of training on the installation and inspection of the uplock assembly.

## Findings

NTSB's coded findings; those marked are part of the probable cause.

- [Maintenance: installation](https://openairdocs.org/ntsb-findings/02062035): Personnel issues › Task performance · Maintenance personnel (probable cause); cases with it: [Bombardier CL-600-2B19, 1 case](https://openairdocs.org/ntsb-findings/02062035/cases.md?model=1390008), [All aircraft, 371 cases](https://openairdocs.org/ntsb-findings/02062035/cases.md)
- [Experience/qualifications: total experience w/ equipment](https://openairdocs.org/ntsb-findings/02031025): Personnel issues › Experience/knowledge · Maintenance personnel (probable cause); cases with it: [Bombardier CL-600-2B19, 1 case](https://openairdocs.org/ntsb-findings/02031025/cases.md?model=1390008), [All aircraft, 269 cases](https://openairdocs.org/ntsb-findings/02031025/cases.md)
- [Inspection: post maintenance inspection](https://openairdocs.org/ntsb-findings/02061515): Personnel issues › Task performance · Maintenance personnel (probable cause); cases with it: [Bombardier CL-600-2B19, 1 case](https://openairdocs.org/ntsb-findings/02061515/cases.md?model=1390008), [All aircraft, 57 cases](https://openairdocs.org/ntsb-findings/02061515/cases.md)

## Sequence of events

The events NTSB coded, in order, by phase of flight. The defining event best describes what happened.

- [Landing: Landing gear not configured](https://openairdocs.org/ntsb-events/095) (defining event); cases with it: [Bombardier CL-600-2B19, 4 cases](https://openairdocs.org/ntsb-events/095/sequence.md?model=1390008), [All aircraft, 584 cases](https://openairdocs.org/ntsb-events/095/sequence.md)

## Analysis

While configuring the airplane for landing, the flight crew observed a landing gear disagree message and an indication that the left main landing gear was not down and locked. The flight crewmembers followed procedures to address the landing gear disagree message; however, they were unable to get the left landing gear to extend. The captain declared an emergency and chose to land the airplane with only the right main landing gear and nose landing gear extended. The airplane came to rest in an upright, left-wing-low position. Postincident examination of the left main landing gear system revealed that the upper attachment bolt for the left main landing gear uplock assembly, which is designed to be attached to both the uplock mechanism and the structure, was attached only to the airplane structure. The left main landing gear uplock assembly had been removed and reinstalled the day before the incident flight. The mechanic who performed the maintenance did not have training on nor prior experience performing the installation of the uplock assembly, and the maintenance inspector who inspected its installation did not have training on inspecting the uplock assembly. Neither the mechanic nor the maintenance inspector observed any problems during the postinstallation inspection. Thus, it is likely that the uplock assembly was installed incorrectly due to the lack of training in both the installation by the mechanic and the inspection by the inspector.

## Factual narrative

On September 1, 2011, about 1725 central daylight time, a Bombardier CL-600-2B19 airplane, N875AS, operated as Delta Connection flight 5058, landed at the Baton Rouge Metropolitan Airport (BTR), Baton Rouge, Louisiana, with the left main landing gear in the retracted position. The airline transport pilot captain, first officer, flight attendant, and 50 passengers were not injured. The airplane received minor damage. Visual meteorological conditions prevailed for the landing and an instrument flight rules flight plan was filed for the 14 Code of Federal Regulations Part 121 flight. The flight originated from the Hartsfield Jackson Atlanta International Airport (ATL), Atlanta, Georgia, at 1409. While configuring the airplane for landing, the flight crew observed a landing gear disagree message, and the left main gear indicated that it was not down and locked. The Quick Reference Handbook (QRH) procedures were accomplished, which included cycling the landing gear handle and the use of the alternate gear extension (manual release) system; however, the crew was unable to get the left landing gear to extend. The captain declared an emergency and elected to land the airplane with the right main landing gear and nose gear extended. The airplane came to rest in an upright and left wing low position. The captain commanded an evacuation, and all passengers departed the airplane using the left forward door. Post-incident inspection of the airplane revealed minor damage to the left wing. There was no other damage to the airplane as a result of the left main landing gear being retracted at the time of landing. Examination of the left main landing gear assembly revealed that the upper attachment bolt for the left main landing gear uplock assembly, which is designed to be attached to both the uplock mechanism and the structure, was attached to the airplane structure only. Maintenance had been performed on both the left and right main landing gear systems prior to the incident flight. The mechanic who performed the maintenance did not have prior experience performing the installation of the uplock assembly. Following the incident, Atlantic Southeast Airlines changed their maintenance requirements and procedures to prevent future accidents. In addition, Bombardier issued Service Letter ATA:3230 to address this maintenance discrepancy and prevent future accidents.

## Aircraft

- Registration: [N875AS](https://openairdocs.org/aircraft/N875AS), registered now, S/N 7559, built 2001 (OpenAirDocs)
- Reported make and model: BOMBARDIER INC CL-600-2B19
- Registry model: [Bombardier CL-600-2B19](https://openairdocs.org/model/bombardier-cl-600-2b19) (registry code 1390008) (OpenAirDocs)
- Registry engine: [GE CF34 series](https://openairdocs.org/engine/ge-cf34-series) (registry code 30015, turbo-fan) (OpenAirDocs)
- Category: Airplane
- Serial number: 7559
- Airframe hours: 30563
- Engines: General Electric CF34-3B1 9140 lbs thrust turbo fan; General Electric CF34-3B1 9140 lbs thrust turbo fan
- Damage: Minor damage
- Flight: Part 121
- Operator: Atlantic Southeast Airlines Inc
- Registered owner: Atlantic Southeast Airlines Inc
- Airworthiness certificate: Standard, Transport
- Last inspection: AAIP, August 31, 2011
- Departed: ATL, Atlanta, GA
- Destination: BTR, Baton Rouge, LA
- Flight plan: IFR
- Airport: BTR, Baton Rouge Metropolitan, runway 13, 6,407 × 150 ft, asphalt

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 31; injuries: none; airline transport, commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, unknown; last flight review March 18, 2011; seat: left; toxicology performed; flight hours: 5,305 total, 4,312 in this make and model, 198 in the last 90 days
- Co-pilot; age 27; injuries: none; commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, without waivers/limitations; seat: right; restraint: 3-point; flight hours: 998 total, 715 in this make and model, 175 in the last 90 days

## Weather

- Conditions: Visual (VMC), Day
- Wind: 100° at 11 knots
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 84 °F, dew point 75 °F
- Altimeter: 29.94 inHg
- Observed at: BTR

## FAA reports on this event (1)

The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs).

- [Incident 20110901023769I](https://openairdocs.org/incident/20110901023769I), Sep 1, 2011: Bombardier Inc CL-600-2B19, Baton Rouge, LA, Minor damage. The landing gear uplock mechanism was changed just prior to this flight. The mechanism is held in place by two bolts. The upper bolt was found misaligned and…

## Docket (6 files)

The files NTSB released with the investigation on November 21, 2013, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=81683. 1.3 MB in all.

- Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 874 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40403673&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF
- Maintenance Personnel Interview Summaries (item 2, .PDF, 77 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40403679&FileExtension=.PDF&FileName=Maintenance%20Personnel%20Interview%20Summaries-Master.PDF
- Flight Crew Statements (item 3, .PDF, 112 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40403691&FileExtension=.PDF&FileName=Flight%20Crew%20Statements-Redacted.PDF
- Service Letter - Main Landing Gear Up-lock installation - Maintenance Best Practice (item 4, .PDF, 124 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40403692&FileExtension=.PDF&FileName=Service%20Letter%20-%20Main%20Landing%20Gear%20Up-lock%20installation%20-%20Maintenance%20Best%20Practice-Master.PDF
- MXAB 091511 - Installation of UpperLower bolts on MLG Uplock Assembly (item 5, .PDF, 112 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40403693&FileExtension=.PDF&FileName=MXAB%20091511%20-%20Installation%20of%20UpperLower%20bolts%20on%20MLG%20Uplock%20Assembly-Master.PDF
- Cockpit Voice Recorder 12 - Specialist's Factual Report (item 6, .PDF, 48 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40405040&FileExtension=.PDF&FileName=Cockpit%20Voice%20Recorder%2012%20-%20Specialist%27s%20Factual%20Report-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.

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