# NTSB ERA10IA095: Beech 58, N391MC, Lexington, KY, December 10, 2009 - Type: NTSB incident investigation - Classification: Incident · No injuries · Incident investigation · Final report - Date: December 10, 2009, 12:05 local (17:05 UTC) - Place: Lexington, KY - Coordinates: 38.036388, -84.605834 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=38.0364&lon=-84.6058&mi=10 - Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping) - Defining event: [Approach-VFR go-around: Sys/Comp malf/fail (non-power)](https://openairdocs.org/ntsb-events/330) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report May 28, 2010 - Report: Approved by Office Director - NTSB office: Eastern Region Aviation - Parties: Hawker Beechcraft Coorporation, FAA/FSDO - NTSB case key (mKey): 75156 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ERA10IA095 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/75156/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=75156 - Page: https://openairdocs.org/ntsb/ERA10IA095 ## Probable cause The overstress failure of the nose landing gear aft drag brace. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Landing gear system: gear extension and retract sys](https://openairdocs.org/ntsb-findings/01023230): Aircraft › Aircraft systems · Failure (probable cause); cases with it: [Beech 58, 11 cases](https://openairdocs.org/ntsb-findings/01023230/cases.md?model=1152740), [All aircraft, 416 cases](https://openairdocs.org/ntsb-findings/01023230/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Approach-VFR go-around: Sys/Comp malf/fail (non-power)](https://openairdocs.org/ntsb-events/330) (defining event); cases with it: [Beech 58, 6 cases](https://openairdocs.org/ntsb-events/330/sequence.md?model=1152740), [All aircraft, 994 cases](https://openairdocs.org/ntsb-events/330/sequence.md) - [Landing: Landing gear collapse](https://openairdocs.org/ntsb-events/094); cases with it: [Beech 58, 8 cases](https://openairdocs.org/ntsb-events/094/sequence.md?model=1152740), [All aircraft, 1,787 cases](https://openairdocs.org/ntsb-events/094/sequence.md) ## Analysis The pilots were practicing instrument approaches and performed a missed approach. At that time, the landing gear was retracted and the corresponding gear retracted cockpit indication was noted; however, the approach controller advised the pilots that the nose landing gear appeared to remain in the extended position. The pilots then selected the nose landing gear to the extended position and noted the corresponding gear extended cockpit indication. During a subsequent landing, the nose landing gear collapsed and the airplane slid to a stop on the runway. Examination of the airplane revealed that the right side of the nose landing gear aft drag brace had separated. Metallurgical examination revealed that the origin point of the fracture was consistent with overstress, and the fracture extended from the origin point over a significant period of time. The airplane had accumulated over 10,000 hours of flight time, and the initiation of the overstress event was most likely the result of a previous hard landing or landings. Review of the maintenance manual for the make and model airplane revealed that the nose gear was an "on condition" inspection item; however, the fracture was in an area that would not be easily visible or detected by a mechanic during an inspection. ## Factual narrative On December 10, 2009, about 1205 eastern standard time, a Beech 58, N391MC, operated by Air Lexington Inc., incurred minor damage while landing at Blue Grass Airport (LEX), Lexington, Kentucky. The certificated airline transport pilot and certificated commercial pilot were not injured. Visual meteorological conditions prevailed and no flight plan was filed for the local flight, which originated from LEX about 1030. The personal flight was conducted under the provisions of 14 Code of Federal Regulations Part 91. The pilots reported that the commercial pilot was practicing instrument approaches, while the airline transport pilot acted as a safety pilot. During a go-around at LEX, the commercial pilot retracted the landing gear and noted the corresponding gear retracted cockpit indication; however, the LEX Approach controller advised the pilots that the nose landing gear appeared to be in the extended position. The pilots then selected the landing gear to the extended position and noted the corresponding gear extended cockpit indication. During a subsequent landing, after touchdown on runway 22, the nose landing gear collapsed and the airplane slid to a stop on the runway. Examination of the airplane by a Federal Aviation Administration (FAA) airworthiness inspector revealed damage to the nose gear area and both propellers. The examination also revealed that the right side of the nose landing gear aft drag brace had separated. The inspector also noted that the nose landing gear indicating system and linkage remained intact and undamaged. The right side nose landing gear aft drag brace was forwarded to the NTSB Materials Laboratory, Washington, DC. The FAA inspector also forwarded photographs of the damage to a representative of the aircraft manufacturer. The representative noted that review of the photographs revealed that a plug used to contain linoil within the drag brace appeared to be missing. Additionally, the component tubing appeared to be absent of linoil, which was required per Hawker Beechcraft Specification 455. The representative added that the incident airplane was manufactured in 1976 and the manufacturer redesigned the component in 1977 to reduce man-hours required to fabricate the component. The redesigned component was forged and not constructed of tubing, which also eliminated the need for a plug and linoil. The representative further stated that review of the manufacturer’s field condition reports did not reveal any record of similar failures to the same model nose landing gear aft drag brace. Examination of the component by an NTSB metallurgist revealed that the origin point of the fracture exhibited features consistent with overstress. Additionally, the metallurgist noted “crack arrest marks” along the fracture extension, consistent with an overstress failure over a period of time. The fracture initiated from a different area than that of the missing linoil plug. The investigation could not positively determine if the plugdeparted before or after the failure of the component. Review of the maintenance manual for the make and model airplane revealed that the nose gear was an "on condition" inspection item; however, the FAA airworthiness inspector noted that the fracture was in an area that would not be easily visible or detected by a mechanic during an annual or 100-hour inspection. The incident airplane was maintained under an FAA approved inspection program (AAIP). The airplane's most recent AAIP inspection was completed on November 9, 2009. The airplane had accumulated 20.2 hours of operation since that inspection and had accumulated 10,437.3 total hours of operation at the time of the incident. ## Aircraft - Registration: [N391MC](https://openairdocs.org/deregistered/N391MC-2015-05-14), registration cancelled 2015-05-14, S/N TH-756, built 1976 (OpenAirDocs) - Reported make and model: BEECH 58 - Registry model: [Beech 58](https://openairdocs.org/model/beech-58) (registry code 1152740) (OpenAirDocs) - Registry engine: [Continental IO-520 series](https://openairdocs.org/engine/continental-io-520-series) (registry code 17032, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: TH-756 - Airframe hours: 10437 - Engines: CONT MOTOR IO 520 SERIES 285 horsepower reciprocating; CONT MOTOR IO 520 SERIES 285 horsepower reciprocating - Damage: Minor damage - Flight: Personal, Part 91 - Operator: Air Lexington Inc - Registered owner: Air Lexington Inc - Airworthiness certificate: Standard, Normal - Last inspection: AAIP, November 9, 2009, 20 hours before - Departed: LEX, Lexington, KY - Destination: LEX, Lexington, KY - Airport: LEX, Blue Grass Airport, runway 22, 7,003 × 150 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 66; injuries: none; airline transport, commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, with waivers/limitations; last flight review August 30, 2009; seat: right; flight hours: 20,381 total, 1,663 in this make and model, 17,043 as pilot in command, 25 in the last 90 days, 6 in the last 30 days, 0 in the last 24 hours - Pilot; age 33; injuries: none; commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 2, with waivers/limitations; last flight review February 9, 2009; seat: left; flight hours: 3,478 total, 25 in this make and model, 3,130 as pilot in command, 7 in the last 90 days, 7 in the last 30 days, 2 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 250° at 18 knots, gusting 25 - Visibility: 9 statute miles - Lowest ceiling: 3,400 ft broken - Temperature: 23 °F, dew point 12 °F - Altimeter: 30.09 inHg - Observed at: LEX ## 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 20091210052329I](https://openairdocs.org/incident/20091210052329I), Dec 10, 2009: Beech 58, Lexington, KY, No damage. On December 10, 2009 N391MC was being operated under FAR part 91 for ebc currency requirements. The flight originated from Lexington, KY(lex) and various… ## Docket (6 files) The files NTSB released with the investigation on April 6, 2010, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=75156. 7.7 MB in all. - Materials Laboratory 15 - Factual Report 10-029 (item 1, .PDF, 774 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40327359&FileExtension=.PDF&FileName=Materials%20Laboratory%2015%20-%20Factual%20Report%2010-029-Master.PDF - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 2, .PDF, 5.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40327381&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Interview Summary (item 3, .PDF, 25 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40327382&FileExtension=.PDF&FileName=Interview%20Summary-Master.PDF - Correspondence From Airplane Manufacturer (item 4, .PDF, 17 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40327383&FileExtension=.PDF&FileName=Correspondence%20From%20Airplane%20Manufacturer-Master.PDF - Excerpt From Maintenance Manual (item 5, .PDF, 634 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40327388&FileExtension=.PDF&FileName=Excerpt%20From%20Maintenance%20Manual-Master.PDF - Statement of Party Representatives to NTSB Investigation (item 6, .PDF, 408 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40328243&FileExtension=.PDF&FileName=Statement%20of%20Party%20Representatives%20to%20NTSB%20Investigation-Redacted.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.