# NTSB CEN10LA315: Beech 1900D, N195GL, Denver, CO, June 12, 2010 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: June 12, 2010, 16:25 local (22:25 UTC) - Place: Denver, CO - Coordinates: 39.861667, -104.673057 - Nearby events: https://openairdocs.org/map.md?lat=39.8617&lon=-104.6731&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Defining event: [Landing-landing roll: Landing gear collapse](https://openairdocs.org/ntsb-events/094) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report January 7, 2011 - Report: Approved by Office Director - NTSB office: Central Region - Parties: FAA Flight Standards District Office - NTSB case key (mKey): 76305 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN10LA315 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/76305/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=76305 - Page: https://openairdocs.org/ntsb/CEN10LA315 ## Probable cause The pre-existent damage of the right-hand landing gear actuator attachment lug which led to fatigue cracking and eventual overload failure resulting in a collapsed gear upon landing. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Landing gear system: landing gear actuator](https://openairdocs.org/ntsb-findings/01023233): Aircraft › Aircraft systems · Fatigue/wear/corrosion (probable cause); cases with it: [Beech 1900D, 3 cases](https://openairdocs.org/ntsb-findings/01023233/cases.md?model=1154162), [All aircraft, 54 cases](https://openairdocs.org/ntsb-findings/01023233/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Initial climb: Aircraft structural failure](https://openairdocs.org/ntsb-events/337); cases with it: [Beech 1900D, 1 case](https://openairdocs.org/ntsb-events/337/sequence.md?model=1154162), [All aircraft, 290 cases](https://openairdocs.org/ntsb-events/337/sequence.md) - [Landing-landing roll: Landing gear collapse](https://openairdocs.org/ntsb-events/094) (defining event); cases with it: [Beech 1900D, 3 cases](https://openairdocs.org/ntsb-events/094/sequence.md?model=1154162), [All aircraft, 1,787 cases](https://openairdocs.org/ntsb-events/094/sequence.md) ## Analysis When the crew retracted the landing gear after takeoff, they heard a loud "bang." When they lowered the gear, all three landing gear annunciator lights indicated SAFE, but the left gear light also indicated IN TRANSIT. After consulting with their maintenance department, the crew landed and, during rollout, the left main gear collapsed. Postaccident examination revealed the drag leg assembly was fractured. When the gear collapsed, a portion of the wing spar was torn out. Metallurgical examination revealed that both lugs that attach to the landing gear actuator and the rig plate were fractured and the drag leg was bent. The right-hand lug contained a fatigue crack that progressed to an overload failure. The other lug fractured completely through overload. The damage was pre-existent to that cracking, and served as a stress concentrator leading to the initiation of a fatigue crack. Spectrographic analysis of the upper drag leg arm showed that it met specified chemical composition requirements. At time of accident the aircraft had operated about 82.9 hours and 95 cycles since a detailed inspection of the landing gear was accomplished on May 28, 2010; no discrepancies related to the lug were noted at that time. ## Factual narrative On June 12, 2010, approximately 1625 mountain daylight time, a Beech 1900D, N195GL, registered to and operated by Great Lakes Aviation, Ltd., Cheyenne, Wyoming, was substantially damaged when the left main landing gear collapsed on landing at Denver International Airport (DEN), Denver, Colorado. Visual meteorological conditions (VMC) prevailed at the time of the accident. The positioning flight was being conducted under the provisions of Title 14 Code of Federal Regulations (CFR) Part 91, and an instrument flight rules (IFR) flight plan had been filed. The airline transport certificated captain and commercial certificated first officer, the only occupants aboard, were not injured. The cross-country flight had just originated, and was destined for Cheyenne, Wyoming. When the crew retracted the landing gear after takeoff, they heard a loud "bang." The crew circled the airport. When they lowered the landing gear, all three landing gear annunciator lights indicated SAFE, but the IN TRANSIT annunciator light also illuminated. After consulting with their maintenance department, the crew landed on runway 35R. During rollout, the left main gear collapsed. Post-accident examination revealed the drag leg assembly was fractured. When the gear collapsed, a portion of the wing spar bent. On July 22, 2010, acting on behalf of the National Transportation Safety Board, representatives of the Federal Aviation Administration examined the drag leg assembly at Hawker Beechcraft’s Metallurgical Engineering Laboratory in Wichita, Kansas. Also in attendance were representatives from Great Lakes Aviation. The examination revealed that both lugs that attach to the landing gear actuator were fractured, as was the rig plate. The drag leg was bent. The right hand lug contained a fatigue crack that progressed to an overload failure. The other lug fractured completely through overload. Beach marks associated with the fatigue crack were clearly visible. The fracture surface was damaged by mating crack face abrasion. Striations and mechanical damage was also noted. The damage was pre-existent to the cracking, and served as a stress concentrator leading to the initiation of a fatigue crack. The upper drag leg arm is made of aluminum alloy 7075 in the T6 temper. Spectrographic analysis showed that the material met the chemical composition requirements of that specification. Aerospace Material Specification (AMS) 2658 requires this material in the T6 temper to have a minimum Rockwell hardness of B scale 84 and a conductivity between 30.5 % IACS (International Annealed Copper Standard) and 36 % IACS. The drag leg had a Rockwell hardness of B87.7 and displayed an electrical conductivity of 32% IACS. ## Aircraft - Registration: [N195GL](https://openairdocs.org/aircraft/N195GL), registered now, S/N UE-195, built 1996 (OpenAirDocs) - Reported make and model: Beech 1900D - Registry model: [Beech 1900D](https://openairdocs.org/model/beech-1900d) (registry code 1154162) (OpenAirDocs) - Registry engine: [Pratt & Whitney PT6A series](https://openairdocs.org/engine/pratt-whitney-pt6a-series) (registry code 52032, turbo-prop) (OpenAirDocs) - Category: Airplane - Serial number: UE-195 - Engines: Pratt & Whitney PT6A-67D 1279 horsepower turbo prop - Damage: Substantial damage - Flight: Ferry, Part 91 - Operator: Great Lakes Aviation, Ltd. - Registered owner: Great Lakes Aviation, Ltd. - Airworthiness certificate: Standard, Transport - Departed: DEN, Denver, CO - Destination: CYS, Cheyenne, WY - Flight plan: IFR - Airport: DEN, Denver International, runway 35R, 12,000 × 150 ft, concrete ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 24; injuries: none; airline transport, flight instructor, commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, with waivers/limitations; last flight review March 20, 2010; seat: left; flight hours: 3,100 total, 2,400 in this make and model - Co-pilot; age 29; injuries: none; flight instructor, commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, without waivers/limitations; last flight review January 20, 2010; seat: right; flight hours: 1,650 total, 1,100 in this make and model, 495 as pilot in command, 225 in the last 90 days, 75 in the last 30 days, 5 in the last 24 hours ## Weather - Conditions: Instrument (IMC), Day - Wind: 10° at 7 knots - Visibility: 2 statute miles - Lowest ceiling: 1,000 ft broken - Temperature: 50 °F, dew point 46 °F - Altimeter: 30.17 inHg - Observed at: DEN ## 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 20100612039289A](https://openairdocs.org/incident/20100612039289A), Jun 12, 2010: Beech 1900D, Denver, CO, Substantial damage. On June 14, 2010, glba director of ops reported:this part 91 reposition flight was to be operated from den to cys it returned to land in den. The crew reported… ## Docket (11 files) The files NTSB released with the investigation on September 23, 2010, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=76305. 30.0 MB in all. - NTSB Form 6120.1-2, Pilot-Operator Aircraft Accident Report (item 1, .PDF, 14.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40336819&FileExtension=.PDF&FileName=NTSB%20Form%206120.1-2,%20Pilot-Operator%20Aircraft%20Accident%20Report-Redacted.PDF - Captain's Statement (item 2, .PDF, 578 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40334755&FileExtension=.PDF&FileName=Captain%27s%20Statement-Redacted.PDF - First Officer's Statement (item 3, .PDF, 749 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40334756&FileExtension=.PDF&FileName=First%20Officer%27s%20Statement-Redacted.PDF - Hawker Beechcraft Metallurgical Report, Drag Leg Assembly (item 4, .PDF, 10.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40336706&FileExtension=.PDF&FileName=Hawker%20Beechcraft%20Metallurgical%20Report,%20Drag%20Leg%20Assembly-Redacted.PDF - Diagram, Main Landing Gear Installation (item 5, .PDF, 47 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40336489&FileExtension=.PDF&FileName=Diagram,%20Main%20Landing%20Gear%20Installation-Master.PDF - Weather Reports and Records (item 6, .PDF, 35 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40333932&FileExtension=.PDF&FileName=Weather%20Reports%20and%20Records-Master.PDF - Photo 1. The airplane on runway with collapsed left main landing gear. (item 7, .PDF, 795 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40336304&FileExtension=.PDF&FileName=Photo%201.%20The%20airplane%20on%20runway%20with%20collapsed%20left%20main%20landing%20gear.-Master.PDF - Photo 2. Broken drag leg. (item 8, .PDF, 764 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40336305&FileExtension=.PDF&FileName=Photo%202.%20Broken%20drag%20leg.-Master.PDF - Photo 3. Right side of of upper drag leg assembly arm. (item 9, .PDF, 828 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40336306&FileExtension=.PDF&FileName=Photo%203.%20Right%20side%20of%20of%20upper%20drag%20leg%20assembly%20arm.-Master.PDF - Photo 4. Left side of upper drag leg assembly arm. (item 10, .PDF, 901 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40336307&FileExtension=.PDF&FileName=Photo%204.%20Left%20side%20of%20upper%20drag%20leg%20assembly%20arm.-Master.PDF - Photo 5. Broken lug. (item 11, .PDF, 528 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40336308&FileExtension=.PDF&FileName=Photo%205.%20Broken%20lug.-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.