# NTSB WPR21LA224: Cessna 172G, N3871L, Washington, CA, June 2, 2021 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 3 · Limited · Final report - Date: June 2, 2021, 08:00 local (15:00 UTC) - Place: Washington, CA - Coordinates: 39.413003, -120.74969 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=39.4130&lon=-120.7497&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute-cruise: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Western Pacific Region - Parties: Yuba-Sutter Aviation Inc., Reno FSDO - NTSB case key (mKey): 103226 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR21LA224 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/103226/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=103226 - Page: https://openairdocs.org/ntsb/WPR21LA224 ## Probable cause A total loss of engine power during an enroute climb due to a stuck exhaust valve and multiple failed piston compression rings. ## 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 · Malfunction (probable cause); cases with it: [Cessna 172G, 1 case](https://openairdocs.org/ntsb-findings/01058530/cases.md?model=2072420), [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-cruise: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) (defining event); cases with it: [Cessna 172G, 10 cases](https://openairdocs.org/ntsb-events/341/sequence.md?model=2072420), [All aircraft, 3,820 cases](https://openairdocs.org/ntsb-events/341/sequence.md) ## Analysis The pilot reported that he was climbing the airplane at full engine power and an airspeed of 80 mph, and he had progressively leaned the fuel/air mixture during the climb. About 6,000 ft mean sea level (msl), he noted that the the engine oil temperature was indicating its maximum limit of 240°F. The pilot lowered the nose to increase airspeed and reduced engine power to cool the engine. About 10 minutes later, the engine oil temperature decreased below redline and he resumed his climb with a slightly richer mixture setting. About 8,500 ft msl, the engine produced a “backfire” sound, the engine rpm decreased, and a loss of engine power ensued. The pilot declared an emergency and performed a forced landing to mountainous terrain, during which the airplane sustained substantial damage. Examination of the engine revealed that the No. 2 cylinder’s piston exhibited a stuck top compression ring. The No. 3 cylinder exhibited a stuck exhaust valve, and the No. 3 piston’s top compression ring had separated into two. The No. 5 intake valve exhibited excessive clearance within its guide. The No. 6 cylinder’s piston top compression ring had separated into four pieces. A review of the airframe and engine maintenance logbooks indicated that the last annual inspection was completed 6 months before the accident. At the time of the annual inspection, the engine had amassed a total time of 4,027 hours, and 1,896 hours since major overhaul. The engine tachometer indicated 2,277 hours during the last annual inspection and indicated 2,288.8 at the time of the accident. The engine-manufacturer recommended overhaul interval is 1,800 hours or 12 years, whichever occurs first. ## Factual narrative On June 02, 2021, about 1000 Pacific daylight time, a Cessna 172G, N3871L, was substantially damaged when it was involved in an accident near Washington, California. The pilot and the passenger were not injured. The airplane was operated as a Title 14 Code of Federal Regulations (CFR) Part 91 personal flight. The pilot reported that the airplane was climbing at full power at 80 mph, and he progressively leaned the mixture during the climb. About 30 minutes into the climb profile, the airplane’s altitude was near 6,000 ft msl, and the pilot observed that the airplane’s engine oil temperature gauge had reached its maximum limit of 240°F. He attempted to arrest the increasing oil temperature by lowering the nose of the airplane to increase airspeed and subsequently decreased the engine power setting. About 10 minutes later, the oil temperature decreased below 240°F and the pilot resumed his climb to 9,500 ft msl using a richer mixture setting. About 8,500 ft msl, the pilot heard the engine produce a “backfire” type sound, and confirmed a loss of engine power as he observed the engine rpm gradually decrease. The pilot began to troubleshoot but was unable to restore engine power. Unable to maintain altitude, he declared an emergency and maneuvered the airplane toward a clear area within the mountainous terrain. During the forced landing, the airplane sustained substantial damage to both wings and the lower fuselage. A review of the airframe and engine maintenance logbooks indicated that the last annual inspection was completed 6 months before the accident, on December 6, 2020. At the time of the annual inspection, the engine had amassed a total time of 4,027 hours, and 1,896 hours since major overhaul. The engine tachometer indicated 2,277 hours during the last annual inspection and indicated 2,288.8 at the time of the accident. The engine-manufacturer recommended overhaul interval is 1,800 hours or 12 years, whichever occurs first. Examination of the engine revealed that magneto-to-engine timing was Left: 33° before top dead center (BTDC) and Right: 32° BTDC. The engine manufacturer specification for magneto-to-engine timing was Left: 28° BTDC and Right: 26° BTDC. About 6 qts of engine oil were extracted from the oil sump. The No. 2 cylinder displayed low compression. All cylinders were removed from the crankcase for further examination. Removal of cylinder Nos. 1 and 4 revealed no anomalies. Removal of the No. 2 cylinder revealed that the top compression ring was seized to the piston ring land, with flat spots observed on the top ring. Removal of the No. 3 cylinder revealed that the top compression ring was broken into two pieces, and the exhaust valve was stuck in the valve guide. Removal of the No. 5 cylinder revealed excessive key-holing of the intake valve within its guide. The No. 6 cylinder top compression ring was broken into four pieces. ## Aircraft - Registration: [N3871L](https://openairdocs.org/deregistered/N3871L-2022-07-30), registration cancelled 2022-07-30, S/N 17254040, built 1965 (OpenAirDocs) - Reported make and model: CESSNA 172G - Registry model: [Cessna 172G](https://openairdocs.org/model/cessna-172g) (registry code 2072420) (OpenAirDocs) - Registry engine: [Continental 0-300 series](https://openairdocs.org/engine/continental-0-300-series) (registry code 17022, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 17254040 - Year built: 1965 - Airframe hours: 3981.8 - Engines: Continental O-300-D 145 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Registered owner: Alexander J. Hyatt Jr - Airworthiness certificate: Standard, Normal - Last inspection: Annual, December 6, 2020, 11.8 hours before - Departed: O52, Yuba City, CA - Destination: RNO, Reno, NV - Equipment: ADS-B, Stall warning system, Handheld GPS ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 86; injuries: none; commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: basicmed; last flight review March 4, 2020; seat: left; restraint: 3-point; flight hours: 7,000 total, 3,000 in this make and model, 6,000 as pilot in command, 5.8 in the last 90 days, 3.4 in the last 30 days, 1.5 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 270° at 3 knots - Visibility: 10 statute miles - Temperature: 79 °F, dew point 41 °F - Altimeter: 30.18 inHg - Observed at: KBLU, 8 nm away - METAR: KBLU 021652Z AUTO 27003KT 10SM CLR 26/05 A3018 RMK AO2 SLP105 T02560050 $ ## 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 20210602012889A](https://openairdocs.org/incident/20210602012889A), Jun 2, 2021: Cessna 172G, Nevada City, CA, Substantial damage. N3871L was repositioning from sutter county airport (O52) to reno-tahoe international airport (krno). While climbing through 6500 feet MSL, the engine appeared… ## Other investigations on N3871L (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 CHI87LA035](https://openairdocs.org/ntsb/CHI87LA035), Nov 22, 1986: Cessna 172G (N3871L), Evansville, IN, substantial damage ## Docket (10 files) The files NTSB released with the investigation on June 14, 2023, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=103226. 15.8 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 9 pages, 4.4 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15417567&FileExtension=pdf&FileName=6120_1_Redacted-Rel.pdf - Record of conversation -pilot and FAA email (item 2, PDF, 2 pages, 160 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15416900&FileExtension=pdf&FileName=Memorandum%20for%20Record-Rel.pdf - Annual inspection -airframe (item 3, PDF, 2 pages, 4.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15417623&FileExtension=pdf&FileName=N3871L%20Airframe%20Annnual%20Last%20page_Redacted-Rel.pdf - Annual inspection -engine (item 4, PDF, 1 page, 1.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15417802&FileExtension=pdf&FileName=N3871L%20Engine%20Annnual%20Last%20page_Redacted-Rel.pdf - Continental service interval -time between overhaul (item 5, PDF, 1 page, 195 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15418510&FileExtension=pdf&FileName=Manufacture%20Time%20Between%20Overhaul-Rel.pdf - N3871L airframe and engine examination report (item 6, PDF, 11 pages, 2.4 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15584088&FileExtension=pdf&FileName=Airframe%20and%20Engine%20Examination%20Report_Redacted-Rel.pdf - Engine manufacture type certificate (item 7, PDF, 1 page, 42 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15458044&FileExtension=pdf&FileName=O300D-Rel.pdf - Photographs (item 8, PDF, 5 pages, 1.4 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15458062&FileExtension=pdf&FileName=Photographs-Rel.pdf - Wreckage release form (item 9, PDF, 1 page, 112 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15474781&FileExtension=pdf&FileName=NTSB%20Release-of-Wreckage-Form-Signed_Redacted-Rel.pdf - Certification of party representative (item 10, PDF, 1 page, 1.4 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15475555&FileExtension=pdf&FileName=CERTIFICATION%20OF%20PARTY%20REPRESENTATIVE_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.