# NTSB CEN19LA249: Cessna A185, N5806J, Saginaw, MI, August 3, 2019 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Class 3 · Limited · Final report - Date: August 3, 2019, 10:00 local (14:00 UTC) - Place: Saginaw, MI - Coordinates: 43.404167, -83.980003 - Nearby events: https://openairdocs.org/map.md?lat=43.4042&lon=-83.9800&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute: Powerplant sys/comp malf/fail](https://openairdocs.org/ntsb-events/340) - Highest injury: Minor injuries - Injuries: 4 minor - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Central Region - Parties: FAA FSDO, Continental Aircraft Engines - ADs cited in the narratives: [AD 2000-23-21](https://openairdocs.org/ad/2000-23-21) (OpenAirDocs) - NTSB case key (mKey): 99988 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN19LA249 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/99988/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=99988 - Page: https://openairdocs.org/ntsb/CEN19LA249 ## Probable cause Maintenance personnel’s failure to properly align the crankshaft during an engine reassembly which led to a fatigue failure of the crankshaft and the loss of all engine power. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Engine (reciprocating): recip engine power section](https://openairdocs.org/ntsb-findings/01058520): Aircraft › Aircraft power plant · Failure (probable cause); cases with it: [Cessna A185E, 1 case](https://openairdocs.org/ntsb-findings/01058520/cases.md?model=2072818), [All aircraft, 233 cases](https://openairdocs.org/ntsb-findings/01058520/cases.md) - [Maintenance: scheduled/routine maintenance](https://openairdocs.org/ntsb-findings/02062010): Personnel issues › Task performance · Maintenance personnel (probable cause); cases with it: [Cessna A185E, 1 case](https://openairdocs.org/ntsb-findings/02062010/cases.md?model=2072818), [All aircraft, 320 cases](https://openairdocs.org/ntsb-findings/02062010/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Enroute: Powerplant sys/comp malf/fail](https://openairdocs.org/ntsb-events/340) (defining event); cases with it: [Cessna A185E, 2 cases](https://openairdocs.org/ntsb-events/340/sequence.md?model=2072818), [All aircraft, 820 cases](https://openairdocs.org/ntsb-events/340/sequence.md) - [Enroute: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341); cases with it: [Cessna A185E, 4 cases](https://openairdocs.org/ntsb-events/341/sequence.md?model=2072818), [All aircraft, 3,820 cases](https://openairdocs.org/ntsb-events/341/sequence.md) - [Emergency descent: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Cessna A185E, 4 cases](https://openairdocs.org/ntsb-events/440/sequence.md?model=2072818), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) ## Analysis The pilot was in cruise flight in a single-engine airplane when the engine lost power. He selected a road for the forced landing, during which the airplane impacted a power pole and electrical wires. The airplane came to rest inverted and incurred substantial damage to the airplane’s fuselage and wings. Postaccident examination revealed that the engine’s crankshaft had failed due to fatigue. The accident crankshaft was subject to a mandatory service bulletin (MSB) and subsequent Federal Aviation Administration airworthiness directive (AD) requiring inspection of the crankshaft material for metallurgical anomalies; however, this inspection was not performed on the accident airplane’s crankshaft. A detailed metallurgical examination of the crankshaft revealed that a fatigue crack had progressed through most of the crankshaft web cross section, consistent with relatively low-stress, high cycle fatigue. Because no indications of intergranular fracture or large areas of overstress fracture with the planar dimpled rupture features indicative of thermal damage on the fracture surface were noted, it is unlikely that manufacturing issues resulted in the fatigue cracking even though metallurgical testing revealed that the crankshaft material did not meet specification. Rather, the cracking likely initiated due to stray or excessive wear to the forward journal to web radius. It is further likely that a misalignment during a previous reassembly of the engine that occurred about two years prior when two cylinders were replaced resulted in the failure. Given this information, it is likely that maintenance personnel’s failure to properly align the affected crankshaft during the reassembly resulted in a low-stress high cycle fatigue failure of the crankshaft and the subsequent loss of all engine power. ## Factual narrative On August 3, 2019, about 1000 eastern daylight time, a Cessna 185 airplane, N5806J, was substantially damaged when it was involved in an accident near Saginaw, Michigan. The pilot and three passengers received minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that during cruise flight, the engine lost power. He selected a road for a forced landing; however, the airplane impacted a power pole and electrical wires during the forced landing. The airplane came to rest inverted and incurred substantial damage to the fuselage and wings. The wreckage was moved to an aircraft salvage facility near Springfield, Tennessee, where an examination was conducted by the NTSB Investigator-in-Charge (IIC) and a technical representative from the engine manufacturer. At the time of the examination, the airplane’s tachometer read 1,556.34 hours. The airplane was equipped with a factory-rebuilt Continental IO-520-D reciprocating engine, serial number 812972-R; the serial number on the crankshaft flange was F109804N. The examination noted that the engine could not be rotated by hand. Disassembly of the engine found a broken crankshaft. The broken crankshaft was sent to the NTSB Material Laboratory in Washington, DC, for a detailed examination. The web fracture surface was examined using a scanning electron microscope (SEM). The exam found fatigue striations consistent with fatigue crack propagation. Examination of the fatigue crack initiation sites revealed that many of the initiation sites were obliterated by post-fracture smearing; however, an undamaged site revealed no indications of material defects, such as inclusions, corrosion pits, or voids. There were some indications of streaks or microwear marks along the fracture surface edge. Some parallel microcracks were present in this initiation site. In April 2000, Teledyne Continental Motors issued Mandatory Service Bulletin (MSB) 00-05D to address 11 crankshaft fractures that occurred as a result of manufacturing defects. The MSB provided instructions for obtaining crankshaft core samples for metallurgical evaluation. Crankshafts that did not meet material specifications were required to be replaced with a serviceable crankshaft before further flight. The Federal Aviation Administration (FAA) subsequently issued Airworthiness Directive (AD) 2000-23-21, effective December 12, 2000, requiring compliance with the inspection specified in the MSB. The crankshaft serial number for the accident engine appeared on the MSB page list of, “Noncompliant affected service spare crankshaft by part number – no record of compliance with MSB-00-5 or [Airworthiness Directive] AD 2000-23-21”. Review of the engine maintenance records revealed an entry dated May 10, 2010, that stated, “Continental Service Bulletin MSB00-5 DNA [Does Not Apply] by serial number.” The crankshaft serial number appeared on the MSB page list of “Non-compliant affected service sparecrankshaft by part number – no record of compliance with MSB-00-5 or [Airworthiness Directive] AD 2000-23-21.” Further review of the original MSB 00-5 in the table labeled; “Affected engine models by engine serial number and crankshaft serial number”, did not find any reference to the accident engine or crankshaft serial number. However, in the section labeled: “Affected crankshafts by crankshaft part number and serial number”, the accident crankshaft’s serial number was listed on page 14. The maintenance records also contained an entry dated August 11, 2017, which revealed that the Nos. 2 and 6 cylinder assemblies were replaced with new assemblies at a tachometer reading of 1,516.3 hours. A section of the crankshaft’s propeller flange was sent to Continental, for additional testing in accordance with MSB-00-5. The test sample did not pass the metallurgical exam, and if the testing had been accomplished before the accident in accordance with the MSB, the crankshaft would have been required to be removed from service. ## Aircraft - Registration: [N5806J](https://openairdocs.org/deregistered/N5806J-2021-10-05), registration cancelled 2021-10-05, S/N 18501775, built 1970 (OpenAirDocs) - Reported make and model: Cessna A185 (E) - Registry model: [Cessna A185E](https://openairdocs.org/model/cessna-a185e) (registry code 2072818) (OpenAirDocs) - Registry engine: [Continental IO-520 series](https://openairdocs.org/engine/continental-io-520-series) (registry code 17032, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 18501775 - Year built: 1970 - Airframe hours: 1541.5 - Engines: Continental IO-520-D 300 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, August 25, 2018 - Departed: KFNT, Flint, MI - Destination: KSJX, Beaver Island, MI ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 61; injuries: minor; private; airplane ratings: single-engine sea, single-engine land; instrument ratings: airplane; medical: class 3; last flight review July 22, 2019; seat: left; restraint: lap only; flight hours: 1,500 total, 1,300 in this make and model, 6 in the last 90 days, 6 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: 280° at 6 knots - Visibility: 10 statute miles - Temperature: 75 °F, dew point 57 °F - Altimeter: 30.10 inHg - Observed at: KMBS, 9 nm away ## 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 20190803013279A](https://openairdocs.org/incident/20190803013279A), Aug 3, 2019: Cessna A185E, Saginaw, MI, Substantial damage. On August 3, 2019, at approximately 1000 eastern daylight time, a Cessna 185 on amphibious floats, N5806J, operated by a private pilot was substantially… ## Docket (8 files) The files NTSB released with the investigation on October 26, 2021, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=99988. 21.4 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 12 pages, 769 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=9523400&FileExtension=pdf&FileName=NSTB%20Form%206120.1-081619_Redacted-Rel.pdf - Maintenance records (excerpts) (item 2, PDF, 5 pages, 1.5 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=9523409&FileExtension=pdf&FileName=Mx%20records_Redacted-Rel.pdf - Maintenance records (excerpt) (item 3, PDF, 1 page, 674 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11668678&FileExtension=pdf&FileName=cylinder_Redacted-Rel.pdf - Mandatory service bulletins (msb) (item 4, PDF, 86 pages, 1.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=9523420&FileExtension=pdf&FileName=MSB-Rel.pdf - Statement of party representatives to NTSB investigation (item 5, PDF, 1 page, 120 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=9523758&FileExtension=pdf&FileName=Signed%20NTSB%20Party%20Letter%208-2017_Redacted-Rel.pdf - Release of aircraft wreckage, NTSB form 6120.15 (item 6, PDF, 1 page, 1.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=9524136&FileExtension=pdf&FileName=Signed%20NTSB%20wreckage%20Release%20form_Redacted-Rel.pdf - Materials laboratory factual report (item 7, PDF, 21 pages, 19 photos, 11.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11503241&FileExtension=pdf&FileName=20-042%20-%20Materials%20Lab%20Factual%20Report%20(CEN19LA249)_Redacted-Rel.pdf - Photos (item 8, PDF, 6 pages, 4.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11669169&FileExtension=pdf&FileName=Photo%201-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.