# NTSB ANC19LA039: Cessna 402, N7947Q, Boise, ID, July 22, 2019 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 3 · Limited · Final report - Date: July 22, 2019, 11:47 local (17:47 UTC) - Place: Boise, ID - Coordinates: 43.561111, -116.21833 - Nearby events: https://openairdocs.org/map.md?lat=43.5611&lon=-116.2183&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: 3 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Alaska Regional Office - Parties: Federal Aviation Administration (FAA) - NTSB case key (mKey): 99925 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC19LA039 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/99925/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=99925 - Page: https://openairdocs.org/ntsb/ANC19LA039 ## Probable cause A ductile overstress fracture failure of the right main landing gear bell crank assembly pivot bolt, which resulted in a collapse of the right main landing gear. ## 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 · Failure (probable cause); cases with it: [Cessna 402B, 1 case](https://openairdocs.org/ntsb-findings/01023211/cases.md?model=207590P), [All aircraft, 66 cases](https://openairdocs.org/ntsb-findings/01023211/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Landing-landing roll: Landing gear collapse](https://openairdocs.org/ntsb-events/094) (defining event); cases with it: [Cessna 402B, 4 cases](https://openairdocs.org/ntsb-events/094/sequence.md?model=207590P), [All aircraft, 1,787 cases](https://openairdocs.org/ntsb-events/094/sequence.md) ## Analysis The pilot reported that, during the landing approach, he selected the landing gear selector switch to the down position, which was followed by "three greens," indicating that the landing gear was down, locked, and safe for landing. He noted that all three occupants verified and verbally confirmed that the landing gear was "down and locked." The airplane landed uneventfully, but as the pilot started a left turn onto the taxiway, the right main landing gear collapsed, and the right wing struck the ground, sustaining substantial damage. A postaccident examination of the landing gear system revealed that the right main landing gear assembly bell crank pivot bolt had sheared and displayed features consistent with a ductile overstress fracture from shear loading. ## Factual narrative On July 22, 2019, about 1147 mountain daylight time, a Cessna 402B airplane, N7947Q, sustained substantial damage when it was involved in an accident near Boise, Idaho. The two pilots and the FAA observer were uninjured. The airplane was operated under Title 14 Code of Federal Regulations (CFR) Part 91, in accordance with a Part 135.297 instrument proficiency check and a Part 135.399 check airman observation flight. The first pilot, who was the operator's director of operations, reported that he was receiving an instrument proficiency check from the second pilot, the operator's chief pilot; with an FAA aviation safety inspector in the passenger cabin observing the check ride for the purposes of a check airman observation flight. The first pilot stated that, after completing a series of required flight maneuvers, they returned to the departure airport, and the airplane was subsequently cleared to land. During the landing approach, he selected the landing gear selector switch to the down position, which was followed by "three greens," indicating that the landing gear was down, locked, and safe for landing. He noted that all three occupants verified and verbally confirmed that the landing gear was "down and locked." The first pilot stated that, after an uneventful landing, the airplane continued down the runway as the airplane decelerated. When the pilot started a left turn to exit the runway, the right main landing gear collapsed, and the right wing impacted the ground, sustaining substantial damage. A postaccident examination of the landing gear system revealed that the right main landing gear assembly bell crank pivot bolt (p/n NAS464P4-26) had sheared and displayed features consistent with a ductile overstress fracture failure. Figure 1, from the applicable parts catalogue, depicts the main landing gear retraction linkage. The affected bolt from the accident airplane is labeled as #29. Figure 1. Cessna 402 Main Landing Gear Retraction Linkage Installation ## Aircraft - Registration: [N7947Q](https://openairdocs.org/deregistered/N7947Q-2020-03-30), registration cancelled 2020-03-30, S/N 402B0397, built 1973 (OpenAirDocs) - Reported make and model: Cessna 402 - Registry model: [Cessna 402B](https://openairdocs.org/model/cessna-402b) (registry code 207590P) (OpenAirDocs) - Registry engine: [Continental TSIO-520 series](https://openairdocs.org/engine/continental-tsio-520-series) (registry code 17040, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 402B0397 - Year built: 1973 - Airframe hours: 24024 - Engines: Continental TSIO-520-EB 300 horsepower reciprocating; Continental TSIO-520-EB 300 horsepower reciprocating - Damage: Substantial damage - Flight: Other work use, Part 91 - Operator: Western Airlines LC - Registered owner: Western Airlines LC - Airworthiness certificate: Standard, Normal - Last inspection: AAIP, July 18, 2019 - Departed: BOI, Boise, ID - Destination: BOI, Boise, ID - Airport: BOI, Boise Air Terminal/Gowen Field, runway 10L, 10,000 × 150 ft, asphalt - Equipment: Stall warning system, ADS-B, Auto-pilot, Onboard weather, Satellite tracking device ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 65; injuries: none; flight instructor, airline transport; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 2, with waivers/limitations; last flight review January 21, 2019; seat: left; restraint: lap only; toxicology performed; flight hours: 11,300 total, 6,800 in this make and model, 8,300 as pilot in command, 65 in the last 90 days, 18 in the last 30 days - Check pilot; age 64; injuries: none; commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, with waivers/limitations; last flight review June 3, 2019; seat: right; restraint: lap only; flight hours: 5,790 total, 1,260 in this make and model, 5,712 as pilot in command, 102 in the last 90 days, 32 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: variable at 5 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 86 °F - Observed at: BOI ## 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 20190722012409A](https://openairdocs.org/incident/20190722012409A), Jul 22, 2019: Cessna 402B, Boise, ID, Substantial damage. Upon landing rollout of runway 10L boi, the CE402 right main landing gear suddenly collapsed. As a result, the aircraft veered off the right side of the… ## Other investigations on N7947Q (1) 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. - [NTSB MKC84LA048](https://openairdocs.org/ntsb/MKC84LA048), Dec 29, 1983: Cessna 402B (N7947Q), Davenport, IA, substantial damage ## Docket (4 files) The files NTSB released with the investigation on February 2, 2022, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=99925. 2.9 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 9 pages, 1.5 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13139390&FileExtension=pdf&FileName=6120_Redacted-Rel.pdf - Cessna 402 illustrated parts catalogue - excerpt (item 2, PDF, 2 pages, 538 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13139680&FileExtension=pdf&FileName=IPC%20Pages-Rel.pdf - Textron aviation air safety investigations statement (item 3, PDF, 1 page, 121 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13139290&FileExtension=pdf&FileName=Memo%20Style_Redacted-Rel.pdf - Photos (item 4, PDF, 2 pages, 769 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13156561&FileExtension=pdf&FileName=Photo%20Array-Rel.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.