# NTSB CHI06FA158: McDonnell Douglas DC-9-83, N961TW, Chicago, IL, June 20, 2006 - Type: NTSB accident investigation - Classification: Accident · No injuries · Field investigation · Final report - Date: June 20, 2006, 06:30 local (11:30 UTC) - Place: Chicago, IL - Coordinates: 41.97861, -87.904724 - Nearby events: https://openairdocs.org/map.md?lat=41.9786&lon=-87.9047&mi=10 - Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 136 uninjured - Status: Completed, report November 29, 2007 - Report: Approved by Office Director - Parties: Allied Pilots Association, American Airlines, Boeing, FAA - NTSB case key (mKey): 63963 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI06FA158 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/63963/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=63963 - Page: https://openairdocs.org/ntsb/CHI06FA158 ## Probable cause The jammed nose landing gear due to a failure of the nose landing gear spray deflector for undetermined reasons. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, approach - landing gear,nose gear - failure (cause) - landing gear,nose gear - jammed (cause) - Wheels up landing, emergency landing - terrain condition - runway ## Analysis The airplane was damaged during landing with the nose landing gear in the up position. According to statements from the flight crew and communications transcripts, the flight crew attempted to lower the landing gear and did not receive a gear down indication for the nose landing gear. The flight crew requested and performed a low-approach at which time the air traffic control tower personnel confirmed that the nose landing gear was not extended. The flight crew executed a climb to 6,000 feet and contacted American Airlines maintenance in an attempt to troubleshoot the problem. After performing the steps in the appropriate emergency checklists, including an attempted manual extension of the nose landing gear, proved unsuccessful, the flight crew executed a landing on runway 14R with the main landing gear extended and the nose landing gear in the up position. Examination of the airplane revealed that the nose landing gear spray deflector center link had fractured and the right hand urethane deflector was displaced. The deflector was rotated aft and was not in the track within the wheel well that contains the deflector when in the retracted position. When attempting to lower the nose landing gear, the deflector was observed to impinge on the nose landing gear wheel well structure preventing the nose landing gear from extending. The nose landing gear spray deflector components were sent to the NTSB Materials Laboratory for examination. The center deflector assembly was fractured along three separate lines where the right side deflector is attached. The aft right side of the center deflector was fractured through the bolt holes and the vertical and horizontal plate members. Magnified optical examinations of the three fracture faces revealed rough, crystalline matte gray surfaces consistent with overstress separations in cast aluminum alloys at each location. No evidence of porosity, corrosion or preexisting cracking was noted on any of the fracture faces. The engineering drawing specified the center deflector, p/n 5952241, as cast aluminum alloy C355 per federal specification QQ-A-596, solution heat treated and aged to T61 temper. A Brinell hardness impression on a piece of the center deflector measured 101 HB, which was consistent with the specified alloy and heat treatment. ## Factual narrative HISTORY OF FLIGHT On June 20, 2006, about 0630 central daylight time, a McDonnell Douglas DC-9-83, N961TW, piloted by an airline transport pilot, sustained substantial damage during a nose-wheel up landing on runway 14R (13,000 feet by 200 feet, asphalt/concrete), at the O'Hare International Airport (ORD), Chicago, Illinois. The 14 CFR Part 121 domestic passenger flight was being operated by American Airlines as flight 1740. There were no injuries to the 131 passenger and 5 crewmembers. The flight originated from the Los Angeles International Airport (LAX), Los Angeles, California, about 2350 pacific daylight time. According to statements from the flight crew and communications transcripts, the flight crew attempted to lower the landing gear and did not receive a gear down indication for the nose landing gear. The flight crew requested and performed a low-approach at which time the air traffic control tower personnel confirmed that the nose landing gear was not extended. The flight crew executed a climb to 6,000 feet and contacted American Airlines maintenance in an attempt to troubleshoot the problem. After performing the steps in the appropriate emergency checklists, including an attempted manual extension of the nose landing gear, proved unsuccessful, the flight crew executed a landing on runway 14R with the main landing gear extended and the nose landing gear in the up position. PERSONNEL INFORMATION The captain held an airline transport pilot certificate with a multi-engine airplane rating. The certificate listed a type rating for DC-9 airplanes. The certificate also listed commercial pilot privileges for single engine airplanes. The captain's most recent fist class medical certificate was issued on April 12, 2006. The first officer held an airline transport pilot certificate with single and multi-engine airplane ratings. The certificate listed a type rating for second in command privileges in DC-9 airplanes. The first officer's most recent second class medical certificate was issued on December 18, 2005. AIRCRAFT INFORMATION The airplane was a McDonnell Douglas DC-9-83 transport category airplane. Two Pratt and Whitney JT8D series engines producing 20,850 pounds of thrust each powered the airplane. The airplane was configured to seat 136 occupants including 131 passengers, 3 cabin crewmembers and 2 flight crewmembers. The airplane had a retractable tricycle landing gear configuration. METEOROLOGICAL INFORMATION The reported weather conditions at ORD at 0553 were: Winds variable at 4 knots; Visibility 10 statute miles; Scattered clouds at 25,000 feet; Temperature 18 degrees C.; Dew point 14 degrees C.; Altimeter setting 30.03 inches of Mercury. WRECKAGE AND IMPACT INFORMATION Examination of the airplane revealed that the nose landing gear spray deflector center link had fractured and the right hand urethane deflector was displaced. The deflector was rotated aft and was not in the track within the wheel well that contains the deflector when in the retracted position. When attempting to lower the nose landing gear, the deflector was observed to impinge on the nose landing gear wheel well structure preventing the nose landing gear from extending. TESTS AND RESEARCH The nose landing gear spray deflector components were sent to the NTSB Materials Laboratory for examination. The center deflector assembly was fractured along three separate lines where the right side deflector is attached. The aft right side of the center deflector was fractured through the bolt holes and the vertical and horizontal plate members. Magnified optical examinations of the three fracture faces revealed rough, crystalline matte gray surfaces consistent with overstress separations in cast aluminum alloys at each location. No evidence of porosity, corrosion or preexisting cracking was noted on any of the fracture faces. The engineering drawing specified the center deflector, p/n 5952241, as cast aluminum alloy C355 per federal specification QQ-A-596, solution heat treated and aged to T61 temper. A Brinell hardness impression on a piece of the center deflector measured 101 HB, which was consistent with the specified alloy and heat treatment. During the investigation it was discovered that another DC-9 type airplane had arrived at ORD with a broken spray deflector. This airplane's landing gear did extend and the airplane made an uneventful landing. The spray deflector from this airplane had fractures in the same general location as those of the accident airplane's deflector. During the investigation, it was found that airline personnel have access to and use a type of towbarless tug on various aircraft. Tests by the airline confirmed that the tug can apply an upward force to the spray deflector of DC-9 type airplanes. No determination could be made as to whether either the accident airplane or the other DC-9 with the broken spray deflector had been moved using one of the towbarless tugs during the preceding several days. ADDITIONAL INFORMATION The Federal Aviation Administration, Boeing, American Airlines, and the Allied Pilots Association were parties to the investigation. ## Aircraft - Registration: [N961TW](https://openairdocs.org/aircraft/N961TW), registered now, S/N 53611, built 1999 (OpenAirDocs) - Reported make and model: McDonnell Douglas DC-9-83 - Registry model: [Mcdonnell Douglas DC-9-83(MD-83)](https://openairdocs.org/model/mcdonnell-douglas-dc-9-83-md-83) (registry code 3022083) (OpenAirDocs) - Registry engine: [Pratt & Whitney JT8D series](https://openairdocs.org/engine/pratt-whitney-jt8d-series) (registry code 52053, turbo-jet) (OpenAirDocs) - Category: Airplane - Serial number: 53611 - Airframe hours: 20836 - Engines: Pratt & Whitney JT8D-217A 20850 lbs thrust turbo fan; Pratt & Whitney JT8D-217A 20850 lbs thrust turbo fan - Damage: Substantial damage - Flight: Part 121 - Registered owner: American Airlines - Airworthiness certificate: Standard, Transport - Last inspection: Continuous airworthiness, November 1, 2005 - Departed: LAX, LOS ANGELES, CA - Destination: ORD, Chicago, IL - Flight plan: IFR - Airport: ORD, Chicago O'Hare Intl, runway 14R, 13,000 × 200 ft, concrete ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 46; injuries: none; flight instructor, commercial, airline transport, flight engineer; airplane ratings: single-engine sea, multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, with waivers/limitations; last flight review December 1, 2005; seat: left; flight hours: 17,000 total, 9,000 in this make and model, 9,500 as pilot in command, 180 in the last 90 days, 55 in the last 30 days, 0 in the last 24 hours - Co-pilot; age 40; injuries: none; flight instructor, airline transport; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 2, without waivers/limitations; last flight review February 1, 2006; seat: right; flight hours: 6,573 total, 270 in this make and model, 2,622 as pilot in command, 161 in the last 90 days, 61 in the last 30 days, 10 in the last 24 hours - Co-pilot; age 40; injuries: none; flight instructor, airline transport, flight engineer; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1; last flight review December 1, 2005; seat: right ## Weather - Conditions: Visual (VMC), Day - Wind: variable at 4 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 64 °F, dew point 57 °F - Altimeter: 30.03 inHg - Observed at: ORD ## 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 20060620030979A](https://openairdocs.org/incident/20060620030979A), Jun 20, 2006: Doug DC983, Chicago, IL, Substantial damage. (-23) On June 20, 2006, American airlines aircraft, N961TW a DC-9-82, on a flight from los angeles, CA (lax) to O'Hare international airport (ord), Chicago IL,… ## Docket (17 files) The files NTSB released with the investigation on February 27, 2013, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=63963. 10.6 MB in all. - Materials Laboratory 15 - Factual Report 06-103 (item 1, .PDF, 1.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40269682&FileExtension=.PDF&FileName=Materials%20Laboratory%2015%20-%20Factual%20Report%2006-103-Master.PDF - Flight Data Recorder 10 - Specialist's Factual Report (item 2, .PDF, 169 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40267210&FileExtension=.PDF&FileName=Flight%20Data%20Recorder%2010%20-%20Specialist%27s%20Factual%20Report-Master.PDF - Flight Data Recorder 10 - Attachment 1: Tabular Data for Plots 1 and 2 (item 3, .CSV, 1.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40267211&FileExtension=.csv&FileName=Flight%20Data%20Recorder%2010%20-%20Attachment%201%3A%20Tabular%20Data%20for%20Plots%201%20and%202-Master.csv - Flight Data Recorder 10 - Attachment 2: Tabular Data for Plot 3 (item 4, .CSV, 35 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40267212&FileExtension=.csv&FileName=Flight%20Data%20Recorder%2010%20-%20Attachment%202%3A%20Tabular%20Data%20for%20Plot%203-Master.csv - Flight Data Recorder 10 - Attachment 3: Tabular Data for Plot 4 (item 5, .CSV, 35 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40267213&FileExtension=.csv&FileName=Flight%20Data%20Recorder%2010%20-%20Attachment%203%3A%20Tabular%20Data%20for%20Plot%204-Master.csv - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 6, .PDF, 382 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40282990&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - ATC Transcripts (item 7, .PDF, 202 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40282991&FileExtension=.PDF&FileName=ATC%20Transcripts-Master.PDF - Maintenance Information (item 8, .PDF, 306 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40282992&FileExtension=.PDF&FileName=Maintenance%20Information-Master.PDF - Statement of Party Representatives to NTSB Investigation (item 9, .PDF, 297 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40282993&FileExtension=.PDF&FileName=Statement%20of%20Party%20Representatives%20to%20NTSB%20Investigation-Master.PDF - Release of Aircraft Wreckage, NTSB Form 6120.15 (item 10, .PDF, 64 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40387072&FileExtension=.PDF&FileName=Release%20of%20Aircraft%20Wreckage,%20NTSB%20Form%206120.15-Redacted.PDF - Photo 1. Overall View of Aircraft (item 11, .PDF, 1.4 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40282995&FileExtension=.PDF&FileName=Photo%201.%20%20Overall%20View%20of%20Aircraft-Master.PDF - Photo 2. View of Nose Landing Gear Area (item 12, .PDF, 1.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40282996&FileExtension=.PDF&FileName=Photo%202.%20%20View%20of%20Nose%20Landing%20Gear%20Area-Master.PDF - Photo 3. View of Nose Landing Gear Area (item 13, .PDF, 1.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40282997&FileExtension=.PDF&FileName=Photo%203.%20%20View%20of%20Nose%20Landing%20Gear%20Area-Master.PDF - Photo 4. View of Jammed Nose Landing Gear (item 14, .PDF, 1.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40282998&FileExtension=.PDF&FileName=Photo%204.%20%20View%20of%20Jammed%20Nose%20Landing%20Gear-Master.PDF - Photo 5. View of Nose Landing Gear Spray Deflector (item 15, .PDF, 1.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40282999&FileExtension=.PDF&FileName=Photo%205.%20%20View%20of%20Nose%20Landing%20Gear%20Spray%20Deflector-Master.PDF - Photo 6. View of Jammed Nose Landing Gear (item 16, .PDF, 258 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40283000&FileExtension=.PDF&FileName=Photo%206.%20%20View%20of%20Jammed%20Nose%20Landing%20Gear-Master.PDF - Cockpit Voice Recorder 12 - Factual Report of Group Chairman (item 17, .PDF, 74 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40318770&FileExtension=.PDF&FileName=Cockpit%20Voice%20Recorder%2012%20-%20Factual%20Report%20of%20Group%20Chairman-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.