# NTSB CEN24LA011: Cirrus SR22, N6JA, Red Oak, IA, October 15, 2023 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 3 · Limited · Final report - Date: October 15, 2023, 09:51 local (14:51 UTC) - Place: Red Oak, IA - Coordinates: 41.010833, -95.258861 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=41.0108&lon=-95.2589&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute-cruise: Powerplant sys/comp malf/fail](https://openairdocs.org/ntsb-events/340) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Central Region - Parties: FAA, Cirrus Aircraft - NTSB case key (mKey): 193240 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN24LA011 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/193240/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=193240 - Page: https://openairdocs.org/ntsb/CEN24LA011 ## Probable cause The fatigue failure of the exhaust valve due to excessive combustion deposits, which resulted in a partial loss of engine power. Contributing to the accident was the pilot’s failure to ensure that the required scheduled maintenance was completed. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Engine (reciprocating)](https://openairdocs.org/ntsb-findings/01058500): Aircraft › Aircraft power plant · Not serviced/maintained (probable cause); cases with it: [All aircraft, 497 cases](https://openairdocs.org/ntsb-findings/01058500/cases.md) - [Maintenance: scheduled/routine maintenance](https://openairdocs.org/ntsb-findings/02062010): Personnel issues › Task performance · Pilot (probable cause); cases with it: [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-cruise: Powerplant sys/comp malf/fail](https://openairdocs.org/ntsb-events/340) (defining event); cases with it: [All aircraft, 820 cases](https://openairdocs.org/ntsb-events/340/sequence.md) - [Landing-landing roll: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis The pilot reported that the engine began to run rough during the cross-country flight, and the pilot diverted to a nearby non-tower-controlled airport, where he flew the RNAV (GPS) approach to runway 5, the airport’s longest runway. During the descent and approach, the air traffic controller informed the pilot that runway 5 was closed; however, the pilot proceeded to land, and the airplane impacted a barricade and ground equipment, which resulted in substantial damage to the left wing. Examination of the engine found excessive combustion products on the No. 4 cylinder exhaust valve. The deposits wore the valve guide, which resulted in the improper seat of the valve, abnormal valve operation, and fatigue failure of the valve face. The excessive combustion product deposits were most likely due to a rich fuel/air mixture, which prevented the cylinder from reaching the temperature required to ensure that lead combustion products were expelled from the cylinder with the exhaust gas. Review of the airplane’s maintenance records revealed that the engine was 15 days overdue for an annual inspection. Had the required inspection had been performed on time, the exhaust valve issues likely would have been discovered before the accident occurred. ## Factual narrative On October 15, 2023, about 0951 central daylight time, a Cirrus SR22 airplane, N6JA, was substantially damaged when it was involved in an accident at Red Oak Municipal Airport (RDK), Red Oak, Iowa. The pilot and passenger were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. ADS-B flight track information revealed that the airplane departed Eppley Airfield (OMA), Omaha, Nebraska, at 0920 and climbed to 7,000 ft mean sea level (msl) enroute to St Louis Downtown Airport (CPS), St Louis, Illinois. The pilot encountered icing conditions at 7,000 ft msl and requested a climb from air traffic control (ATC) to 9,000 ft msl. After climbing above the clouds into visual meteorological conditions, the engine began to run rough and engine power indications began to fluctuate. The pilot diverted to RDK, a non-tower-controlled airport, and flew the RNAV (GPS) runway 5 approach. During the descent and arrival to RDK, the controller informed the pilot twice that runway 5 was closed. The pilot proceeded to land on runway 5, and the airplane impacted a barricade and ground equipment, which resulted in substantial damage to the left wing. Postaccident examination of the engine and subsequent laboratory testing by the National Transportation Safety Board Materials Lab revealed that the No. 4 cylinder exhaust valve failed as a result of wear of the exhaust valve guide. The wear of the valve guide caused the valve to seat improperly, which led to valve head deformation, hard contact of the valve head with the valve seat, and failure of the exhaust valve rotocoil. A portion of the valve face exited the No. 4 cylinder through the exhaust system and entered the left side turbocharger assembly. The exhaust turbine blades received damage along the leading blade edges before the valve face exited through the left side exhaust. The fractured valve face was not recovered. The No. 4 exhaust valve head was fractured. The combustion face was covered with combustion products and some regions exhibited a red/purple tint. The fracture initiated in the fillet on the downstream-facing side of the valve head and progressed through the head to the combustion face. The origin sustained some post-fracture impact damage, but there were no apparent pre-existing anomalies at the crack origin. The valve head’s seat face was worn and the valve head was dished/mushroomed and the valve stem displayed a buildup of combustion products below the region that engaged the valve guide The No. 4 exhaust rotocoil was worn and the race was covered in cooked oil except for a 0.080-inch-wide annular track that the spring contacted. The spring was worn flat on the side that contacted the washer. Borescope examinations of the remaining cylinders showed that the No. 6 cylinder exhaust valve face displayed uneven heat damage consistent with a failing valve. Review of the airframe and engine maintenance records showed that the airplane’s most recentannual inspection was completed on September 25, 2022. RDK was equipped with three runways; runway 5/23, which was 5,100 ft long by 75 ft wide; runway 17/35, which was 2,901 ft long by 60 ft wide; and runway 13/31, which was grass and measured 2,050 ft long by 210 ft wide. GPS instrument approach procedures were available for runways 5 and 17. ## Aircraft - Registration: N6JA (not matched to a registry record) - Reported make and model: CIRRUS SR22 (T) - Category: Airplane - Serial number: 0845 - Year built: 2013 - Airframe hours: 1441.5 - Engines: Continental TSIO-550K reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, September 25, 2022 - Departed: OMA, Omaha, NE - Destination: CPS, St Louis, MO - Flight plan: IFR - Airport: KRDK, Red Oak Municipal, runway 5, 5,100 × 75 ft, concrete - Equipment: ADS-B ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 52; injuries: none; private; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 3, without waivers/limitations; last flight review February 6, 2023; seat: left; restraint: 3-point; flight hours: 403 total, 398 in this make and model, 403 as pilot in command, 41 in the last 90 days, 13 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 340° at 9 knots - Visibility: 10 statute miles - Lowest ceiling: 6,000 ft overcast - Temperature: 48 °F, dew point 48 °F - Altimeter: 30.32 inHg - Observed at: KRDK - METAR: KRDK 151415Z AUTO 34009KT 10SM OVC060 09/09 A3032 ## 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 20231015018549A](https://openairdocs.org/incident/20231015018549A), Oct 15, 2023: Cirrus SR22T, Red Oak, IA, Substantial damage. Pilot indicated engine started a medium vibration while entering cruise flight above a cloud layer with icing. Pilot requested nearest airport from ATC and was… ## Docket (14 files) The files NTSB released with the investigation on February 20, 2025, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=193240. 73.4 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 12 pages, 1.5 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16402317&FileExtension=pdf&FileName=6120%20combined_Redacted-Rel.pdf - FAA inspector statement - aircraft exam (item 2, PDF, 5 pages, 1.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16402423&FileExtension=pdf&FileName=FAA%20Inspector%20Statements%20-%20Aircraft%20Exam-Rel.pdf - Engine follow-up examination summary (item 3, PDF, 6 pages, 734 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18199993&FileExtension=pdf&FileName=Engine%20Exam-Rel.pdf - Engine maintenance logbook (complete) (item 4, PDF, 13 pages, 10.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=17816093&FileExtension=pdf&FileName=Engine%20Logbook%20Complete_Redacted-Rel.pdf - Maintenance logs - excerpt of last annual inspection (item 5, PDF, 3 pages, 2.4 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16402634&FileExtension=pdf&FileName=Mx%20Logs%20-%20Excerpt%20of%20Last%20Annual%20Inspection_Redacted-Rel.pdf - Photos (item 6, PDF, 2 pages, 1.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16402527&FileExtension=pdf&FileName=Photos-Rel.pdf - Garmin data - accident flight (item 7, CSV, 1.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16402868&FileExtension=csv&FileName=Garmin%20Log%20-%20Accident%20Flight-Rel.csv - Air traffic control communication mor (item 8, PDF, 1 page, 64 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18200297&FileExtension=pdf&FileName=ATC%20MOR-Rel.pdf - Engine data plot (item 9, PDF, 2 pages, 649 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=17816083&FileExtension=pdf&FileName=Engine%20Plot-Rel.pdf - Meteorology factual report (item 10, PDF, 22 pages, 2.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16710863&FileExtension=pdf&FileName=CEN24LA011%20-%20Red%20Oak,%20IA%20Weather%20Factual-Rel.pdf - Meteorology attachment 1 - goes-16 abi snow/ice satellite imagery (item 11, GIF, 18.4 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16711316&FileExtension=gif&FileName=GOES-16%20Band%205%20icing%20channel%20animation-Rel.gif - Meteorology attachment 2 - goes-16 geocolor satellite imagery (item 12, GIF, 25.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16710923&FileExtension=gif&FileName=GOES-16%20GeoColo%20animation-Rel.gif - Materials laboratory factual report 24-038 (item 13, PDF, 21 pages, 24 photos, 4.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=17352457&FileExtension=pdf&FileName=Materials%20Laboratory%20Factual%20Report%2024-038-Rel.pdf - Statement of party representatives to NTSB investigation (item 14, PDF, 1 page, 907 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16402224&FileExtension=pdf&FileName=Signed%20Party%20Form%20Cirrus_Redacted-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.