# NTSB WPR19LA117: Nanchang CJ 6, N621JM, Grass Valley, CA, April 19, 2019 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Class 3 · Limited · Final report - Date: April 19, 2019, 13:40 local (20:40 UTC) - Place: Grass Valley, CA - Coordinates: 39.223888, -121.013336 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=39.2239&lon=-121.0133&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Defining event: [Landing-landing roll: Runway excursion](https://openairdocs.org/ntsb-events/300) - Highest injury: Minor injuries - Injuries: 2 minor - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Western Pacific Region - Parties: Federal Aviation Administration - NTSB case key (mKey): 99293 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR19LA117 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/99293/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=99293 - Page: https://openairdocs.org/ntsb/WPR19LA117 ## Probable cause A loss of brake control due to fatigue fracture of the brake control cable, which resulted in the separation of the cable from the brake handle. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Landing gear system: brake](https://openairdocs.org/ntsb-findings/01023242): Aircraft › Aircraft systems · Failure (probable cause); cases with it: [Jiangxi Hongdu AV Ind CJ-6, 1 case](https://openairdocs.org/ntsb-findings/01023242/cases.md?model=05622JA), [All aircraft, 297 cases](https://openairdocs.org/ntsb-findings/01023242/cases.md) - [Use of equip/info: aircraft control](https://openairdocs.org/ntsb-findings/02063040): Personnel issues › Task performance · Pilot; cases with it: [Jiangxi Hongdu AV Ind CJ-6, 1 case](https://openairdocs.org/ntsb-findings/02063040/cases.md?model=05622JA), [All aircraft, 9,295 cases](https://openairdocs.org/ntsb-findings/02063040/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: Loss of control on ground](https://openairdocs.org/ntsb-events/230); cases with it: [Jiangxi Hongdu AV Ind CJ-6, 1 case](https://openairdocs.org/ntsb-events/230/sequence.md?model=05622JA), [All aircraft, 4,585 cases](https://openairdocs.org/ntsb-events/230/sequence.md) - [Landing-landing roll: Runway excursion](https://openairdocs.org/ntsb-events/300) (defining event); cases with it: [Jiangxi Hongdu AV Ind CJ-6, 1 case](https://openairdocs.org/ntsb-events/300/sequence.md?model=05622JA), [All aircraft, 3,643 cases](https://openairdocs.org/ntsb-events/300/sequence.md) - [Landing-landing roll: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Jiangxi Hongdu AV Ind CJ-6, 1 case](https://openairdocs.org/ntsb-events/470/sequence.md?model=05622JA), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) - [Landing-landing roll: Nose over/nose down](https://openairdocs.org/ntsb-events/096); cases with it: [Jiangxi Hongdu AV Ind CJ-6, 1 case](https://openairdocs.org/ntsb-events/096/sequence.md?model=05622JA), [All aircraft, 2,287 cases](https://openairdocs.org/ntsb-events/096/sequence.md) ## Analysis During the landing roll, the pilot applied left rudder and lightly depressed the brake handle to exit the runway. About 30° into the left turn, the brakes failed, and the airplane exited the asphalt taxiway surface. Due to obstructions ahead and the downsloping terrain, the pilot applied right rudder and engine power to realign the airplane with the runway. Shortly thereafter, the airplane overran the departure end of the runway and traveled downslope while airborne. The airplane then touched down and impacted a dirt berm before it collided with a fence, nosed over, and came to rest inverted, sustaining substantial damage to the fuselage and both wings. Examination of the airplane revealed that the brake control cable was fractured near the cable thimble and was separated from the brake control handle. The fracture surfaces of the separated cable were consistent with a fatigue fracture. Six of the seven strands of wires exhibited relatively flat fracture surfaces normally oriented to the wire axis, consistent with a progressive fracture mechanism, such as a fatigue fracture. Only one strand and a few of the remaining individual wires showed evidence of minor elongation at the fracture location. It is likely that the cable completely failed during the landing roll when the pilot depressed the brake handle. ## Factual narrative On April 19, 2019, about 1340 Pacific daylight time, a Nanchang CJ-6 airplane, N621JM, was substantially damaged when it was involved in an accident near Grass Valley, California. The pilot and passenger sustained minor injuries. The airplane was operated by the pilot as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that, following an uneventful landing on runway 25, a 4,657 ft long and 75 ft wide asphalt runway, he extended his landing roll due to traffic on one of the taxiways. As the airplane neared the pilot's intended taxiway, he applied left rudder and lightly depressed the brake handle. About 30° into the left turn, the brakes failed, and the airplane exited the asphalt taxiway surface. Due to obstructions ahead and the down sloping terrain, the pilot applied right rudder and engine power to realign the airplane with the runway. Shortly after, the airplane overran the departure end of the runway and traveled downslope while airborne. The airplane then touched down and struck a dirt berm before it collided with a fence, nosed over, and came to rest inverted, resulting in substantial damage to the fuselage and both wings. The wreckage was recovered to a secure location for further examination. Postaccident examination revealed that the brake cable was separated from the brake handle. The cable thimble, clevis pin, and cotter pin remained attached to the brake control handle. The separated portions of the cable were removed and sent to the NTSB Materials Laboratory for further examination. Examination of the brake cable revealed that it was constructed of seven strands of seven metal wires (7x7). When comparing the thimble with the cable contour between two fracture locations, the fit was consistent with a thimble-eye termination created by a hand-tucked splice joint, as seen in figure 1. Figure 1: View of the brake cable components submitted to the NTSB Materials Laboratory. The fracture surface of the cleaned cable was examined using a scanning electron microscope. Six of the seven strands of wires exhibited relatively flat fracture surfaces normally oriented to the wire axis, consistent with a progressive fracture mechanism, such as a fatigue fracture. Only one strand and a few of the remaining individual wires showed evidence of minor elongation at the fracture location. For further information, see the Materials Laboratory Factual Report within the public docket for this accident. No specific entries pertaining to the brake cable were found within the airframe logbook. ## Aircraft - Registration: [N621JM](https://openairdocs.org/deregistered/N621JM-2021-01-23), registration cancelled 2021-01-23, S/N 4632023, built 1989 (OpenAirDocs) - Reported make and model: Nanchang CJ 6 (A) - Registry model: [Jiangxi Hongdu AV Ind CJ-6](https://openairdocs.org/model/jiangxi-hongdu-av-ind-cj-6) (registry code 05622JA) (OpenAirDocs) - Registry engine: [Housai 6JIA](https://openairdocs.org/engine/housai-6jia) (registry code 34200, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 4632023 - Year built: 1989 - Airframe hours: 2760.2 - Engines: Huosai 6JIA 285 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Annual, April 5, 2018, 36.2 hours before - Departed: AUN, Auburn, CA - Destination: GOO, Grass Valley, CA - Airport: GOO, Nevada County, runway 25, 4,657 × 75 ft, asphalt - Equipment: Handheld GPS ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 72; injuries: minor; private; airplane ratings: single-engine land; medical: class 3, without waivers/limitations; seat: front; restraint: 5-point; flight hours: 1,594 total, 368 in this make and model, 1,509 as pilot in command, 5 in the last 90 days, 4 in the last 30 days, 2 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 240° at 6 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 37 °F, dew point 43 °F - Altimeter: 29.98 inHg - Observed at: KGOO ## Docket (4 files) The files NTSB released with the investigation on March 8, 2022, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=99293. 3.6 MB in all. - Materials laboratory factual report (item 1, PDF, 7 pages, 5 photos, 1.4 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=9736214&FileExtension=pdf&FileName=19-066%20-%20Materials%20Lab%20Factual%20Report%20(WPR19LA117)-Rel.pdf - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 2, PDF, 9 pages, 1.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13375447&FileExtension=pdf&FileName=small%20NTSB%20Form%206120-1_Redacted-Rel-Rel.pdf - Record of conversation - NTSB investigator (item 3, PDF, 1 page, 72 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=9735628&FileExtension=pdf&FileName=Record%20of%20Conversation%20SS-Rel.pdf - Photo array (item 4, PDF, 2 pages, 2 photos, 1.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=9735776&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.