# NTSB WPR09LA383: Beech 76, N83ER, Glendale, AZ, July 30, 2009 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: July 30, 2009, 15:30 local (22:30 UTC) - Place: Glendale, AZ - Coordinates: 33.530555, -112.293334 - Nearby events: https://openairdocs.org/map.md?lat=33.5306&lon=-112.2933&mi=10 - Phase of flight: [Standing](https://openairdocs.org/ntsb-phases/150) (OpenAirDocs' grouping) - Defining event: [Standing: Landing gear collapse](https://openairdocs.org/ntsb-events/094) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report July 22, 2010 - Report: Approved by Office Director - NTSB office: Western Pacific Region - Parties: Federal Aviation Administration, Hawker Beechcraft - ADs cited in the narratives: AD 91-14-14, [AD 97-06-10](https://openairdocs.org/ad/97-06-10) (OpenAirDocs) - NTSB case key (mKey): 74445 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR09LA383 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/74445/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=74445 - Page: https://openairdocs.org/ntsb/WPR09LA383 ## Probable cause The fatigue failure of the left main landing gear enhanced side brace assembly. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Landing gear system: main landing gear attach sec](https://openairdocs.org/ntsb-findings/01023211): Aircraft › Aircraft systems · Fatigue/wear/corrosion (probable cause) ## Analysis The flight instructor reported that the landing gear warning horn went off while taxiing to the ramp at the conclusion of the instructional flight. After checking that the landing gear handle was down and bringing the airplane to a complete stop, the left main landing gear collapsed, which resulted in substantial damage to the left wing. A subsequent examination of the left main landing gear system revealed that the side frame assembly was the latest enhanced version and had failed as a result of fatigue, consistent with the stresses developed from the bending moments applied to the down tube during the normal extension and retraction of the main landing gear, as well as during takeoff, landing, and taxiing. A search of the relevant data bases disclosed no other reports of similar failures in the new enhanced version of the part. ## Factual narrative On July 30, 2009, about 1530 mountain standard time, a Beech 76, N83ER, sustained substantial damage following the collapse of the left main landing gear while standing at the Glendale Municipal Airport (GEU), Glendale, Arizona. The flight instructor and private pilot receiving instruction were not injured. Visual meteorological conditions prevailed for the local instructional flight, which was operated in accordance with 14 Code of Federal Regulations (CFR) Part 91, and a flight plan was not filed. The flight departed GEU about 1330. In a statement submitted to the Safety Board investigator-in-charge (IIC), the flight instructor reported that after returning from a local training flight and preparing to land at GEU, he observed 3 green lights, indicating that all 3 landing gear were down and locked. The flight instructor stated that after landing and exiting the runway, the after landing checklist was completed, followed by the airplane being taxied to parking. The flight instructor revealed that while taxiing the landing gear warning horn went off, at which time he checked to ensure that the landing gear handle was down. The instructor reported that after the airplane came to a stop the left main landing gear collapsed. An examination revealed that the left wing had sustained substantial damage. A post accident examination of the airplane's landing gear system by a Federal Aviation Administration (FAA) inspector revealed that the left main landing gear's "enhanced side brace assembly" (main landing gear "A" frame assembly), part number 105-810023-75, had failed. The component was forwarded to the NTSB Materials Laboratory in Washington, D.C., for further examination. As a result of the examination, an NTSB engineer reported that the components down tube had fractured adjacent to its fillet weld. The examination also revealed that the location of the fracture regions in the down tube were consistent with the stresses developed from the bending moments applied to the down tube when raising and lowering the main landing gear, as well as during takeoff, landing, and taxiing. In conversations between Hawker Beechcraft Corporation and the IIC, it was revealed that prior to the introduction of the enhanced version of the side brace assembly, the weld cluster version was used. This version was known to have fatigue cracking issues in the down tube near the weld cluster. Federal Aviation Administration (FAA) Airworthiness Directive (AD) 91-14-14, as well as Hawker Beechcraft Service Bulletin 2361, required inspections around the weld cluster and the down tube to address fatigue cracks in an all welded or weld cluster version of the side brace assembly. Subsequently, the enhanced version of the side brace assembly was developed, which uses a new machined fitting to replace the weld cluster of the older part. FAA Airworthiness Directive AD 97-06-10 allows the enhanced part to be used without inspection for fatigue. The side brace that was installed onthe accident airplane was the enhanced version and did not require a fatigue inspection. A review of the NTSB Materials Laboratory database did not reveal any other cases of fatigued side braces with the enhanced machined fitting. ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Standing: Landing gear collapse](https://openairdocs.org/ntsb-events/094) (defining event) ## Aircraft - Registration: [N83ER](https://openairdocs.org/aircraft/N83ER), registered now, S/N ME-201, built 1979 (OpenAirDocs) - Reported make and model: BEECH 76 - Registry model: [Beech 76](https://openairdocs.org/model/beech-76) (registry code 1153005) (OpenAirDocs) - Registry engine: [Lycoming O&VO-360 series](https://openairdocs.org/engine/lycoming-o-vo-360-series) (registry code 41514, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: ME-201 - Airframe hours: 13089 - Engines: Lycoming O-360 180 hp reciprocating; Lycoming O-360 180 hp reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Operator: Air Safety Flight Academy - Registered owner: Christiansen Aviation Inc - Airworthiness certificate: Standard, Normal - Last inspection: Annual, July 24, 2009, 20 hours before - Departed: GEU, Glendale, AZ - Destination: GEU, Glendale, AZ - Airport: GEU, Glendale Municipal Airport, runway 19, 7,150 × 100 ft, concrete ## Flight crew As NTSB recorded them. NTSB leaves out names. - Flight instructor; age 22; injuries: none; commercial, flight instructor; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 3, without waivers/limitations; last flight review May 25, 2009; seat: right; flight hours: 690 total, 38 in this make and model, 587 as pilot in command, 101 in the last 90 days, 36 in the last 30 days, 5 in the last 24 hours - Student pilot; age 24; injuries: none; private; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 1, without waivers/limitations; last flight review May 11, 2009; seat: left; flight hours: 251 total, 26 in this make and model, 166 as pilot in command, 62 in the last 90 days, 36 in the last 30 days, 4 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 240° at 4 knots - Visibility: 20 statute miles - Lowest ceiling: none - Temperature: 106 °F, dew point 48 °F - Altimeter: 29.76 inHg - Observed at: GEU ## 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 20090730014669A](https://openairdocs.org/incident/20090730014669A), Jul 30, 2009: Beech 76, Glendale, AZ, Substantial damage. (-23) On 7/30/2009 at 1510 MST, after performing a normal landing the pilot and student taxied off runway 21 at taxiway A6. The gear warning horn sounded, and… ## Docket (4 files) The files NTSB released with the investigation on May 10, 2010, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=74445. 12.1 MB in all. - Materials Laboratory Factual 09-098 MLG side brace (item 1, .PDF, 2.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40322221&FileExtension=.PDF&FileName=Materials%20Laboratory%20Factual%2009-098%20MLG%20side%20brace-Master.PDF - FAA Airworthiness Directive 97-06-10 (item 2, .PDF, 334 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40329023&FileExtension=.PDF&FileName=FAA%20Airworthiness%20Directive%2097-06-10-Master.PDF - Excerpts from Maintenance Records (item 3, .PDF, 8.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40329024&FileExtension=.PDF&FileName=Excerpts%20from%20Maintenance%20Records-Redacted.PDF - Statement of Party Representatives to NTSB Investigation (item 4, .PDF, 46 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40329025&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.