# NTSB WPR10LA147: Beech 58, N3700N, Portland, OR, February 9, 2010 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: February 9, 2010, 12:02 local (20:02 UTC) - Place: Portland, OR - Coordinates: 45.588611, -122.597503 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=45.5886&lon=-122.5975&mi=10 - Phase of flight: [Takeoff](https://openairdocs.org/ntsb-phases/300) (OpenAirDocs' grouping) - Defining event: [Takeoff: 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: Western Pacific Region - Parties: Federal Aviation Administration - NTSB case key (mKey): 75405 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR10LA147 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/75405/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=75405 - Page: https://openairdocs.org/ntsb/WPR10LA147 ## Probable cause The overstress failure of a nose landing gear mechanism bolt, which precluded the nose gear retract brace assembly from locking the nose gear in the extended position and allowed the nose landing gear to collapse. Contributing to the accident was the failure of the nose gear tire's inner tube. ## 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 58P, 1 case](https://openairdocs.org/ntsb-findings/01023230/cases.md?model=1152744), [All aircraft, 416 cases](https://openairdocs.org/ntsb-findings/01023230/cases.md) - [Landing gear system: tube](https://openairdocs.org/ntsb-findings/01023245): Aircraft › Aircraft systems · Failure (probable cause); cases with it: [Beech 58P, 1 case](https://openairdocs.org/ntsb-findings/01023245/cases.md?model=1152744), [All aircraft, 19 cases](https://openairdocs.org/ntsb-findings/01023245/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Takeoff: Landing gear collapse](https://openairdocs.org/ntsb-events/094) (defining event); cases with it: [Beech 58P, 3 cases](https://openairdocs.org/ntsb-events/094/sequence.md?model=1152744), [All aircraft, 1,787 cases](https://openairdocs.org/ntsb-events/094/sequence.md) ## Analysis During takeoff roll, with the airplane between 60 to 70 knots, the inner tube in the nose gear tire failed, causing the tire to flatten and skid and the nose gear to subsequently collapse. The pilot successfully aborted the takeoff and steered the airplane to a stop onto grass just off the right side of the runway. A postaccident examination of the airplane's nose landing gear retract mechanism revealed that the bolt which connects the mechanism's inboard and outboard arms in place had failed in overstress, likely due to the skidding nose gear tire. The failure of the bolt allowed both arms to pivot enough to keep the nose gear retract brace assembly from locking the nose gear in the extended position, which allowed the nose landing gear to collapse. ## Factual narrative On February 9, 2010, about 1202 Pacific standard time, a Beech 58P, N3700N, sustained substantial damage following a nose landing gear collapse during takeoff roll at the Portland International Airport (PDX), Portland, Oregon. The certificated private pilot and his sole passenger were not injured. Visual meteorological conditions prevailed at the time of the accident, and an instrument flight rules (IFR) flight plan was filed. The personal cross-country flight was being operated in accordance with 14 Code of Federal Regulations Part 91. The flight was originating at the time of the accident, with the destination reported as the Friedman Memorial Airport (SUN), Hailey, Idaho. In a written statement provided to the Safety Board investigator-in-charge (IIC), the pilot reported that during the takeoff roll at about 60 to 70 knots [indicated airspeed], the inner tube in the nose gear failed, which caused the tire to "flatten and skid." The pilot stated that he aborted the takeoff by closing the throttle, and that the "skid" caused the nose wheel downlock to fail, allowing the nose gear to retract. The pilot added that he used main wheel braking to steer the aircraft to a stop on the grass off the right side of the runway. According to a Federal Aviation Administration (FAA) airworthiness inspector who conducted a post accident examination of the airplane, damage was observed to the airplane's most forward bulkhead area and surrounding structure, specifically the left and right keels, which had been ground down by more than one-half inch. It was also revealed during the examination that bolt (part number 130909B20), which connects the inboard and outboard arms of the nose landing gear retract mechanism, had failed. According to a Hawker Beechcraft air safety investigator, when the bolt head separated from the bolt shaft it allowed the inboard arm (p/n 002-820016-29) and the outboard arm (p/n 002-820016-27) to pivot enough to keep the nose gear retract brace assembly from locking the nose gear in the extended position, thus allowing the nose gear to collapse. The IIC submitted the nose landing gear retract mechanism's failed bolt and the inboard arm to the NTSB Materials Laboratory in Washington, D.C. for further examination. The NTSB metallurgist reported that a visual inspection of the mating fracture surfaces of the bolt indicated that the bolt fractured in the grip region about 0.1 inch from the head in a downward shear due to overstress. The metallurgist also reported that the markings on the head of the accident bolt do not meet the marking requirements of AN3. (Refer to NTSB Materials Laboratory Report No. 10-057F, which is in the public docket.) A review of aircraft maintenance records revealed that during the airplane's most recent annual inspection, which was conducted on November 20, 2009, the following entry was made: "...Rigged nose gear retract rod for proper down lock tension." ## Aircraft - Registration: [N3700N](https://openairdocs.org/deregistered/N3700N-2017-09-08), registration cancelled 2017-09-08, S/N TJ-311, built 1980 (OpenAirDocs) - Reported make and model: BEECH 58 (P) - Registry model: [Beech 58P](https://openairdocs.org/model/beech-58p) (registry code 1152744) (OpenAirDocs) - Registry engine: [Continental TSIO-520 series](https://openairdocs.org/engine/continental-tsio-520-series) (registry code 17040, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: TJ-311 - Airframe hours: 2522 - Engines: Teledyne-Continental Motors TSIO-520 325 horsepower reciprocating; Teledyne-Continental Motors TSIO-520 325 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, October 20, 2009, 10 hours before - Departed: PDX, Portland, OR - Destination: SUN, Hailey, ID - Flight plan: IFR - Airport: PDX, Portland International Airport, runway 10L, 8,000 × 150 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 56; injuries: none; private; airplane ratings: multi-engine land, single-engine sea, single-engine land; instrument ratings: airplane; medical: class 2, with waivers/limitations; last flight review January 26, 2010; seat: left; flight hours: 1,883 total, 785 in this make and model, 1,883 as pilot in command, 10 in the last 90 days, 2 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 46 °F, dew point 39 °F - Altimeter: 30.03 inHg - Observed at: PDX ## 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 20100209027489A](https://openairdocs.org/incident/20100209027489A), Feb 9, 2010: Beech 58P, Portland, OR, Substantial damage. The pilot was cleared for takoff from intersection A-6. After normal acceleration, the nose wheel developed a strong vibration. The pilot aborted the takeoff… ## Docket (9 files) The files NTSB released with the investigation on September 27, 2010, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=75405. 2.0 MB in all. - Materials Laboratory Factual Report 10-057 (item 1, .PDF, 193 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40330889&FileExtension=.PDF&FileName=Materials%20Laboratory%20Factual%20Report%2010-057-Master.PDF - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 2, .PDF, 877 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40334367&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Witness Statements Provided by FAA Inspector (item 3, .PDF, 103 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40334368&FileExtension=.PDF&FileName=Witness%20Statements%20Provided%20by%20FAA%20Inspector-Redacted.PDF - Excerpt from Aircraft Maintenance Logbook (item 4, .PDF, 456 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40334369&FileExtension=.PDF&FileName=Excerpt%20from%20Aircraft%20Maintenance%20Logbook-Redacted.PDF - Excerpts from Hawker Beech Illustrated Parts Catalog (item 5, .PDF, 84 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40334370&FileExtension=.PDF&FileName=Excerpts%20from%20Hawker%20Beech%20Illustrated%20Parts%20Catalog-Master.PDF - Record of Report - Hawker Beechcraft Corporation (item 6, .PDF, 36 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40334371&FileExtension=.PDF&FileName=Record%20of%20Report%20-%20Hawker%20Beechcraft%20Corporation-Redacted.PDF - Statement of Party Representatives to NTSB Investigation (item 7, .PDF, 212 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40334372&FileExtension=.PDF&FileName=Statement%20of%20Party%20Representatives%20to%20NTSB%20Investigation-Redacted.PDF - Release of Aircraft Wreckage, NTSB Form 6120.15 (item 8, .PDF, 21 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40334373&FileExtension=.PDF&FileName=Release%20of%20Aircraft%20Wreckage,%20NTSB%20Form%206120.15-Redacted.PDF - NTSB Receipt of Parts Form (item 9, .PDF, 51 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40334374&FileExtension=.PDF&FileName=NTSB%20Receipt%20of%20Parts%20Form-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.