# NTSB WPR20LA133: Cessna 177, N3386T, Lodi, CA, April 29, 2020 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Class 3 · Limited · Final report - Date: April 28, 2020, 17:52 local (Apr 29, 2020, 00:52 UTC) - Place: Lodi, CA - Coordinates: 38.196109, -121.248886 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=38.1961&lon=-121.2489&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Western Pacific Region - Parties: Federal Aviation Administration - NTSB case key (mKey): 101216 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR20LA133 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/101216/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=101216 - Page: https://openairdocs.org/ntsb/WPR20LA133 ## Probable cause The fatigue failure of the no. 4 cylinder connecting rod, which resulted in a total loss of 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 177, 2 cases](https://openairdocs.org/ntsb-findings/01058520/cases.md?model=2073704), [All aircraft, 233 cases](https://openairdocs.org/ntsb-findings/01058520/cases.md) - [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 177, 3 cases](https://openairdocs.org/ntsb-findings/01058530/cases.md?model=2073704), [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 (total)](https://openairdocs.org/ntsb-events/341) (defining event); cases with it: [Cessna 177, 14 cases](https://openairdocs.org/ntsb-events/341/sequence.md?model=2073704), [All aircraft, 3,820 cases](https://openairdocs.org/ntsb-events/341/sequence.md) - [Enroute: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Cessna 177, 17 cases](https://openairdocs.org/ntsb-events/440/sequence.md?model=2073704), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) ## Analysis The student pilot reported that about 15 minutes after takeoff, he heard a loud noise and observed oil on the windscreen, followed by a total loss of engine power. The pilot attempted to restart the engine but was unsuccessful and initiated a forced landing to a nearby field. Subsequently, the airplane landed hard and came to rest upright, which resulted in substantial damage to the fuselage. Postaccident examination of the engine revealed that the No. 4 connecting rod had failed. Metallurgical examination of the connecting rod revealed that it had fractured from a fatigue crack, which initiated at an inner flange corner of the rod, about 1.15 inches from the piston pin bore. Once the connecting rod was no longer connected, the lower portion of the connecting rod (closer to the crankshaft) fractured in bending overstress, beginning a cascade of wider damage while the reciprocating engine was running. ## Factual narrative On April 28, 2020, about 1752 Pacific daylight time, a Cessna 177, N3386T, was substantially damaged when it was involved in an accident near Lodi, California. The pilot sustained minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The student pilot reported that about 15 minutes after takeoff, at an altitude of 1,400 ft, the engine suddenly began to run rough and make metallic noises along with oil on the windscreen, which was followed by a total loss of engine power. The pilot attempted to restart the engine unsuccessfully and initiated a forced landing to a nearby field. Subsequently, the airplane landed hard and came to rest upright. Examination of the engine revealed that the engine remained attached to the airframe, with all accessories attached. A hole in the crankcase was observed above cylinder No. 4 and 3. No loose oil lines were found with the exception of the oil pressure line, which was separated from the crankcase, consistent with impact damage. The No. 4 cylinder exhibited extensive damage to the piston skirt area and cylinder wall. The No. 4 connecting rod remained attached to the crankshaft, however, the web was separated from just outboard of the crankshaft to about 1 inch inboard from the piston pin. The area of separation near the piston pin was flat, with no apparent mechanical damage. The separation near the crankshaft exhibited extensive mechanical damage. The middle portion of the connecting rod web was found within the oil sump and exhibited mechanical damage. See figure 1. Figure 1: View of the No. 4 connecting rod. The middle web section exhibited multiple areas of locally deformed material, mostly along the protruding flange surfaces. These features were consistent with this remnant having been impacted by adjacent components in multiple locations. The fracture surface between this remnant and the crankshaft bore surfaces exhibited a general rounded but perpendicular orientation, with localized buckling on the flanges. The rough orientation and texture suggested overstress fracture, however, the mating surfaces were damaged from post-fracture impact, with no discernible fracture features present. The other fracture surface of the connecting rod, toward the piston pin side, was relatively flat and oriented perpendicular to the rod longitudinal direction. The fracture on the pin side remnant was relatively smooth, exhibiting few elevated features. Most of the fracture surface, which was generally flat in orientation, exhibited crack arrest marks, indicative of progressive crack growth, consistent with fatigue. The remaining fracture surface exhibited a rougher, more undulating surface texture consistent with subsequent overstress fracture, as seen in figure 2. Therefore, the fatigue crack covered about 95% of the rod flange-to-flange cross section, measured as approximately 1.086 inches. Figure 2: The no. 4 connecting rod fracture surface (piston pin side) Thelack of ratchet marks suggested a single initiation site. This site was located at the inside corner of a flange edge. The river patterns and crack arrest marks were consistent with having emanated from this feature. When viewed at an angle, the feature was collocated with an area of local plastic deformation and wear. As shown in figure 3, the outer flange surface had been smoothed, and deformed over the side of the inner flange surface. Figure 3: Angled view of the crack initiation site (arrow), showing inward deformation of the flange side. The engine was overhauled on November 10, 1986 and had accumulated 887.86 hours at the time of the accident. No maintenance entries regarding the No. 4 connecting rod were found throughout the engine logbook. ## Aircraft - Registration: [N3386T](https://openairdocs.org/deregistered/N3386T-2022-02-05), registration cancelled 2022-02-05, S/N 17700686, built 1968 (OpenAirDocs) - Reported make and model: Cessna 177 (Undesignat) - Registry model: [Cessna 177](https://openairdocs.org/model/cessna-177) (registry code 2073704) (OpenAirDocs) - Registry engine: [Lycoming O-360-A1A](https://openairdocs.org/engine/lycoming-o-360-a1a) (registry code 41594, 4 cycle) (OpenAirDocs) - Category: Airplane - Serial number: 17700686 - Year built: 1968 - Airframe hours: 3091.86 - Engines: Lycoming O-360-A1A 180 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, October 1, 2019, 30.26 hours before - Departed: 1O3, Lodi, CA - Equipment: ADS-B, Stall warning system ## Flight crew As NTSB recorded them. NTSB leaves out names. - Student pilot; age 64; injuries: minor; student; medical: class 3, without waivers/limitations; seat: left; restraint: 3-point; flight hours: 84 total, 51 in this make and model, 13 as pilot in command, 12 in the last 90 days, 3 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: 310° at 4 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 91 °F, dew point 54 °F - Altimeter: 29.94 inHg - Observed at: KSCK, 18 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 20200428004589A](https://openairdocs.org/incident/20200428004589A), Apr 28, 2020: Cessna 177, Acampo, CA, Destroyed. On 04/28/2020 at approx. 1752 PST N3386T lost power and crashed in a field in Acampo calfornia. Aircraft was destroyed and pilot received minor injuries. ## Other investigations on N3386T (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 CHI86LA040](https://openairdocs.org/ntsb/CHI86LA040), Dec 5, 1985: Cessna 177 (N3386T), Crookston, MN, substantial damage ## Docket (6 files) The files NTSB released with the investigation on March 24, 2022, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=101216. 15.0 MB in all. - Materials laboratory factual report (item 1, PDF, 21 pages, 28 photos, 11.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13032922&FileExtension=pdf&FileName=21-086%20-%20Materials%20Lab%20Factual%20Report%20(WPR20LA133)-Rel.pdf - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 2, PDF, 11 pages, 1.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13211375&FileExtension=pdf&FileName=NTSB%20report_Redacted-Rel.pdf - NTSB engine examination summary (item 3, PDF, 3 pages, 189 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13211385&FileExtension=pdf&FileName=Engine%20Examination-Rel.pdf - Release of aircraft wreckage, NTSB form 6120.15 (item 4, PDF, 1 page, 914 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13211204&FileExtension=pdf&FileName=SIGNED%20wreckage_releasedocs_Redacted-Rel.pdf - Evidence control form (item 5, PDF, 1 page, 29 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13211289&FileExtension=pdf&FileName=Cylinders%20Evidence%20Control%20Form_Redacted-Rel.pdf - Photo array (item 6, PDF, 3 pages, 3 photos, 916 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13211872&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.