# NTSB WPR22LA351: Cessna 172L, N7917G, Ventura, CA, September 16, 2022 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Class 3 · Limited · Final report - Date: September 16, 2022, 16:30 local (23:30 UTC) - Place: Ventura, CA · Near the beach - Coordinates: 34.254498, -119.26951 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=34.2545&lon=-119.2695&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) - Highest injury: Minor injuries - Injuries: 2 minor, 1 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Western Pacific Region - Parties: Federal Aviation Administration - NTSB case key (mKey): 105963 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR22LA351 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/105963/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=105963 - Page: https://openairdocs.org/ntsb/WPR22LA351 ## Probable cause A partial loss of engine power due to the fatigue fracture of the No. 4 exhaust valve. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Engine (reciprocating): recip eng cyl section](https://openairdocs.org/ntsb-findings/01058530): Aircraft › Aircraft power plant · Fatigue/wear/corrosion (probable cause); cases with it: [Cessna 172L, 1 case](https://openairdocs.org/ntsb-findings/01058530/cases.md?model=2072432), [All aircraft, 373 cases](https://openairdocs.org/ntsb-findings/01058530/cases.md) - [Engine (reciprocating): recip eng cyl section](https://openairdocs.org/ntsb-findings/01058530): Aircraft › Aircraft power plant · Failure (probable cause); cases with it: [Cessna 172L, 1 case](https://openairdocs.org/ntsb-findings/01058530/cases.md?model=2072432), [All aircraft, 373 cases](https://openairdocs.org/ntsb-findings/01058530/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Enroute: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) (defining event); cases with it: [Cessna 172L, 5 cases](https://openairdocs.org/ntsb-events/342/sequence.md?model=2072432), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md) ## Analysis According to the pilot, while conducting a local flight, he heard a "pop" followed by a partial loss of engine power. The airframe started shaking badly, he pulled power to idle, established best glide, and contacted Air Traffic Control (ATC). ATC provided alternate airports and current weather information. Unable to maintain altitude, he initiated a forced landing to a clearing on the beach. During the landing roll, the airplane impacted a rock retaining wall, which resulted in substantial damage to the fuselage and left horizontal stabilizer. Examination of the engine revealed that the No. 4 exhaust valve was fractured. Metallurgical examination of the fracture surfaces on the exhaust valve revealed that it had fractured due to fatigue. The fatigue fracture of the No. 4 exhaust valve likely led to the partial loss of engine power. ## Factual narrative On September 16, 2022, about 1630 Pacific daylight time, a Cessna 172L, N7917G, was substantially damaged when it was involved in an accident near Ventura, California. The pilot was not injured and both passengers sustained minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that, while enroute about 2,000 ft mean sea level (msl), he heard a "pop" followed by a partial loss of engine power. The airframe started shaking badly, he pulled power to idle, established best glide, and contacted Air Traffic Control (ATC). ATC provided alternate airports and current weather information. Unable to maintain altitude, he initiated a forced landing to a clearing on the beach. During the landing roll, the airplane impacted a rock retaining wall. Postaccident examination of the airplane revealed that the left wing and forward fuselage were substantially damaged. Subsequent lighted borescope examination of the airplane’s engine revealed mechanical damage to the No. 4 cylinder’s combustion dome and piston face. The Nos. 3 and 4 cylinders were removed. Metallic debris was observed obstructing the No. 3 cylinder intake valve. The No. 4 cylinder was removed, and remnants of the exhaust valve were observed within the cylinder. The No. 4 cylinder and remnants of the No. 4 exhaust valve were sent to National Transportation Safety Board Materials Laboratory, Washington, DC, for examination. The examination of the fracture surface of the No. 4 exhaust valve revealed characteristics consistent with a fatigue fracture. Review of maintenance records did not reveal any recent maintenance performed on the cylinder. ## Aircraft - Registration: [N7917G](https://openairdocs.org/deregistered/N7917G-2023-04-25), registration cancelled 2023-04-25, S/N 17259617, built 1970 (OpenAirDocs) - Reported make and model: CESSNA 172L - Registry model: [Cessna 172L](https://openairdocs.org/model/cessna-172l) (registry code 2072432) (OpenAirDocs) - Registry engine: [Lycoming 0-320 series](https://openairdocs.org/engine/lycoming-0-320-series) (registry code 41508, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 17259617 - Year built: 1970 - Airframe hours: 2633 - Engines: Lycoming O-320-E2D 150 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, April 1, 2022 - Departed: SZP, Santa Paula, CA - Airport: NA - Equipment: ADS-B, Stall warning system ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 46; injuries: none; private; airplane ratings: single-engine land; medical: class 3, with waivers/limitations; last flight review August 18, 2022; seat: left; restraint: 3-point; flight hours: 108 total, 108 in this make and model, 31 as pilot in command, 16 in the last 90 days, 6 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: 260° at 12 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 72 °F, dew point 61 °F - Altimeter: 29.86 inHg - Observed at: KOXR, 5 nm away - METAR: KOXR 162351Z 26012KT 10SM CLR 22/16 A2986 RMK AO2 SLP112 T02220161 10239 20217 58015 ## 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 20220916015809A](https://openairdocs.org/incident/20220916015809A), Sep 16, 2022: Cessna C172L, Ventura, CA, Substantial damage. At about f/l 2,000' MSL, pilot heard a loud pop in the engine area, followed by loss of engine power, and violently shaking of aircraft. Pilot reduced power… ## Other investigations on N7917G (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 LAX72DUK07](https://openairdocs.org/ntsb/LAX72DUK07), May 23, 1972: Cessna 172L (N7917G), Bisbee, AZ, substantial damage ## Docket (7 files) The files NTSB released with the investigation on May 2, 2024, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=105963. 823 MB in all. - Materials laboratory factual report (item 1, PDF, 22 pages, 23 photos, 8.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15810921&FileExtension=pdf&FileName=23-044%20-%20Materials%20Lab%20Factual%20Report%20(WPR22LA351)-Rel.pdf - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 2, PDF, 10 pages, 3.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14517295&FileExtension=pdf&FileName=Pilot%206120_Redacted-Rel.pdf - Engine maintenance records (item 3, PDF, 14 pages, 807 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=17036508&FileExtension=pdf&FileName=Engine%20Maintenance%20Records_Redacted-Rel.pdf - Airframe and engine exam (item 4, PDF, 11 pages, 1.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16980377&FileExtension=pdf&FileName=WPR22LA351%20Air%20Frame%20and%20Engine-Rel.pdf - Evidence control forms (item 5, PDF, 3 pages, 79 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15898170&FileExtension=pdf&FileName=Evidence%20Control%20Forms-Rel.pdf - Release of aircraft wreckage, NTSB form 6120.15 (item 6, PDF, 1 page, 97 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15818720&FileExtension=pdf&FileName=wpr22la351%20release%20of%20wreckage%20Signed_Redacted-Rel.pdf - Photo array (item 7, PDF, 3 pages, 1.5 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14787005&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.