# NTSB CEN20LA378: Cessna 340, N5178J, Oklahoma City, OK, September 3, 2020 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 3 · Limited · Final report - Date: September 3, 2020, 07:15 local (12:15 UTC) - Place: Oklahoma City, OK - Coordinates: 35.469852, -97.519767 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=35.4699&lon=-97.5198&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute-climb to cruise: Aircraft structural failure](https://openairdocs.org/ntsb-events/337) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Central Region - Parties: FAA - NTSB case key (mKey): 101914 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN20LA378 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/101914/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=101914 - Page: https://openairdocs.org/ntsb/CEN20LA378 ## Probable cause A failure of the windscreen for reasons that could not be determined based on available evidence. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Windows-windshield system: flight compartment windows](https://openairdocs.org/ntsb-findings/01035610): Aircraft › Aircraft structures · Failure (probable cause); cases with it: [Cessna 340A, 1 case](https://openairdocs.org/ntsb-findings/01035610/cases.md?model=2076405), [All aircraft, 42 cases](https://openairdocs.org/ntsb-findings/01035610/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Enroute-climb to cruise: Aircraft structural failure](https://openairdocs.org/ntsb-events/337) (defining event); cases with it: [Cessna 340A, 1 case](https://openairdocs.org/ntsb-events/337/sequence.md?model=2076405), [All aircraft, 290 cases](https://openairdocs.org/ntsb-events/337/sequence.md) ## Analysis While climbing through 17,000 ft mean sea level (msl) during a cross-country flight, the pilot completed a transition check and verified that the cabin pressure altitude was 8,000 ft and the pressure differential was within limits. As the airplane climbed through 18,000 ft msl, the right windscreen blew out. The pilot returned to the departure airport and landed the airplane without further incident. Six pieces of acrylic material that comprised the complete outer circumference of the windscreen remained attached to the airframe. The section of windscreen that was blown out during flight was unaccounted for. The fracture surfaces of the remnants were consistent with overstress separation. The pilot’s statement of events did not indicate a malfunction of the aircraft’s pressurization system. The origination point of the failure was not identified, and the reason for the windscreen failure could not be determined based on available evidence. ## Factual narrative On September 3, 2020, a Cessna 340 airplane, N5178J, was substantially damaged when it was involved in an accident near Oklahoma City, Oklahoma. The pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot was flying from Oklahoma to Texas. He performed a transition check as the airplane passed through 17,000 ft mean sea level (msl) and the cabin pressure altitude was 8,000 ft. He noted the pressure differential was 3, which was below the maximum pressure differential of 4.3. About 50 miles southwest of Oklahoma City, as the airplane passed 18,000 ft msl, the right windscreen blew out. The pilot returned to the departure airport and landed without further incident. As the windscreen is considered part of the structure of a pressurized aircraft; the airplane was substantially damaged. Six pieces of acrylic material that comprised the complete outer circumference of the windshield remained within the airframe (see figure 1). The remnants measured approximately 35 inches tall by 31 inches wide when laid out on a flat surface as oriented when installed. The blown-out section of the windshield material, measuring about 21 inches by 31 inches, was not recovered. Figure 1. Remaining windscreen Examination of the windscreen remnants found no significant signs of aging and no visible signs of crazing. The fracture surfaces were consistent with overstress separation. The origination point of the failure could not be identified on the available remnants. ## Aircraft - Registration: [N5178J](https://openairdocs.org/aircraft/N5178J), registered now, S/N 340A0013 (OpenAirDocs) - Reported make and model: Cessna 340 (A) - Registry model: [Cessna 340A](https://openairdocs.org/model/cessna-340a) (registry code 2076405) (OpenAirDocs) - Registry engine: [Continental TSIO-520 series](https://openairdocs.org/engine/continental-tsio-520-series) (registry code 17040, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 340A0013 - Year built: 1975 - Airframe hours: 6585 - Engines: Continental TSIO-520 SER reciprocating; Continental TSIO-520 SER reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Operator: Skymed Llc - Registered owner: Skymed Llc - Airworthiness certificate: Standard, Normal - Last inspection: Annual, November 1, 2019 - Destination: KMBQ, Burnet, TX - Flight plan: IFR - Airport: KHSD - Equipment: ADS-B, Auto-pilot ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 46; injuries: none; airline transport; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, with waivers/limitations; last flight review October 22, 2019; seat: left; flight hours: 3,500 total, 686 in this make and model, 2,900 as pilot in command, 135 in the last 90 days, 30 in the last 30 days, 5 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Visibility: 6 statute miles ## 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 20200903021609A](https://openairdocs.org/incident/20200903021609A), Sep 3, 2020: Cessna 340A, Oklahoma City, OK, Minor damage. Departure was normal approximately 20 minutes into the flight, the pilot heard a loud bang. The pilot looked and Realized that the copilot windshield was no… ## Docket (4 files) The files NTSB released with the investigation on May 19, 2022, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=101914. 13.0 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 11 pages, 1.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12072376&FileExtension=pdf&FileName=6120_1web_Reader%20copy_Redacted-Rel.pdf - C340 service manual extract (item 2, PDF, 1 page, 9.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12071650&FileExtension=pdf&FileName=340A%20MM%20Pressuization%20system%20Extracts-Rel.pdf - Photos (item 3, PDF, 3 pages, 3 photos, 1.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12073335&FileExtension=pdf&FileName=Photo%20Array%20CEN20LA378-Rel.pdf - Memorandum of record - windshield examination (item 4, PDF, 2 pages, 1 photo, 547 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12082727&FileExtension=pdf&FileName=Memorandum%20of%20Record%20-%20Windshield%20Exam-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.