# NTSB WPR21LA069: Cessna 172, N5098E, San Diego, CA, December 13, 2020 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 3 · Limited · Final report - Date: December 13, 2020, 12:50 local (20:50 UTC) - Place: San Diego, CA · Airport environment - Coordinates: 32.815722, -117.13955 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=32.8157&lon=-117.1395&mi=10 - Phase of flight: [Takeoff](https://openairdocs.org/ntsb-phases/300) (OpenAirDocs' grouping) - Defining event: [Takeoff: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Western Pacific Region - Parties: FAA - NTSB case key (mKey): 102410 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR21LA069 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/102410/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=102410 - Page: https://openairdocs.org/ntsb/WPR21LA069 ## Probable cause A partial loss of engine power due to the fatigue fracture of the No. 3 exhaust valve rocker arm stud. ## 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 172N, 13 cases](https://openairdocs.org/ntsb-findings/01058530/cases.md?model=2072434), [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 172N, 13 cases](https://openairdocs.org/ntsb-findings/01058530/cases.md?model=2072434), [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. - [Takeoff: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) (defining event); cases with it: [Cessna 172N, 23 cases](https://openairdocs.org/ntsb-events/342/sequence.md?model=2072434), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md) - [Landing: Runway excursion](https://openairdocs.org/ntsb-events/300); cases with it: [Cessna 172N, 81 cases](https://openairdocs.org/ntsb-events/300/sequence.md?model=2072434), [All aircraft, 3,643 cases](https://openairdocs.org/ntsb-events/300/sequence.md) - [Landing: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Cessna 172N, 134 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=2072434), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis According to the flight instructor, the purpose of the flight was for the student pilot to practice touch-and-go landings. During the second takeoff, as the airplane was about 100-150 ft above ground level, he detected a loss of engine power and assumed control of the airplane. He landed the airplane on the remaining runway but overran the departure end of the runway and struck the airport perimeter fence. Both wings sustained substantial damage. Examination of the engine revealed that the No. 3 exhaust rocker arm stud was fractured. Metallurgical examination of the fracture surfaces on the rocker arm stud revealed that it had fractured due to fatigue. The fatigue fracture of the No. 3 exhaust valve rocker arm stud likely led to the partial loss of engine power. ## Factual narrative On December 13, 2020, about 1250 Pacific standard time, a Cessna 172, N5098E, was substantially damaged when it was involved in an accident near San Diego, California. The flight instructor and student were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 instructional flight. The flight instructor reported that the purpose of the flight was for the student pilot to practice touch-and-go landings. During the second takeoff on runway 28R, as the airplane was about 100-150 ft above ground level, the flight instructor detected a loss of engine power and assumed control of the airplane. He landed the airplane on the remaining runway; however, the airplane overran the departure end of the runway and struck and airport perimeter fence. Postaccident examination of the airplane by a Federal Aviation Administration inspector revealed that both wings and the fuselage sustained substantial damage. Subsequent examination of the airplane’s engine revealed that the No. 3 cylinder’s intake shroud tube was bent. Removal of the No. 3 cylinder’s rocker box cover identified the exhaust valve rocker arm stud had separated. The exhaust valve rocker arm seat, rocker arm, washer, and a section of the stud with self-locking nut were loose within the rocker box cover. Fretting was observed at the mating surface for the rocker arm seat, the rocker arm seat, the shroud tube and the push rod assembly. The rocker arm stud was sent to National Transportation Safety Board Materials Laboratory, Washington, DC, for examination. The examination of the fracture surface revealed characteristics consistent with a fatigue fracture. Review of maintenance records did not reveal if the stud was ever replaced or inspected during the major overhaul. ## Aircraft - Registration: [N5098E](https://openairdocs.org/deregistered/N5098E-2022-12-31), registration cancelled 2022-12-31, S/N 17271711, built 1978 (OpenAirDocs) - Reported make and model: CESSNA 172 (N) - Registry model: [Cessna 172N](https://openairdocs.org/model/cessna-172n) (registry code 2072434) (OpenAirDocs) - Registry engine: [Lycoming 0-320 series](https://openairdocs.org/engine/lycoming-0-320-series) (registry code 41508, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 17271711 - Year built: 1978 - Airframe hours: 6653 - Engines: Lycoming O-320-H2AD 160 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Operator: Plus One Flyers - Registered owner: Seven 4 Zulu LLC - Airworthiness certificate: Standard, Normal; Standard, Utility - Last inspection: Annual, February 3, 2020 - Airport: MYF, Montgomery-Gibbs Executive, runway 28R, 4,598 × 150 ft, asphalt - Equipment: ADS-B, Electronic primary flight display, Stall warning system ## Flight crew As NTSB recorded them. NTSB leaves out names. - Flight instructor; age 33; injuries: none; commercial, flight instructor; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 1, without waivers/limitations; last flight review June 4, 2020; seat: left; flight hours: 413 total, 381 in this make and model, 347 as pilot in command, 33 in the last 90 days, 9 in the last 30 days - Student pilot; age 43; injuries: none; student; medical: class 3, without waivers/limitations; seat: left; flight hours: 60 total, 60 in this make and model ## Weather - Conditions: Visual (VMC), Day - Wind: 250° at 9 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 66 °F, dew point 28 °F - Altimeter: 30.18 inHg - Observed at: KMYF - METAR: KMYF 132053Z 25009KT 10SM CLR 19/M02 A3018 RMK AO2 SLP219 T01941017 58021 ## 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 20201213020719A](https://openairdocs.org/incident/20201213020719A), Dec 13, 2020: Cessna 172N, San Diego, CA, Substantial damage. During this training flight, the student pilot had completed a takeoff and a touch & go landing to runway 28R. During the 2nd takeoff from 28R and on climbout,… ## Docket (8 files) The files NTSB released with the investigation on June 22, 2022, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=102410. 9.0 MB in all. - Materials laboratory factual report 21-063 (item 1, PDF, 7 pages, 12 photos, 2.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12667850&FileExtension=pdf&FileName=21-063-Rel.pdf - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 2, PDF, 9 pages, 1.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11768958&FileExtension=pdf&FileName=WPR21LA069%20NTSB%206120%20CFI_Redacted-Rel.pdf - Record of phone conversation (owner) (item 3, PDF, 1 page, 165 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12059293&FileExtension=pdf&FileName=Record%20of%20phone%20conversation%20(Owner)-Rel.pdf - Engine exam (item 4, PDF, 5 pages, 2.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12058497&FileExtension=pdf&FileName=Engine%20Exam_Redacted-Rel.pdf - Recovery statements (item 5, PDF, 7 pages, 424 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12883938&FileExtension=pdf&FileName=Recovery%20statements_Redacted-Rel.pdf - Release of aircraft wreckage, NTSB form 6120.15 (item 6, PDF, 1 page, 147 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12156275&FileExtension=pdf&FileName=wreckage%20release_Redacted-Rel.pdf - Evidence control form (item 7, PDF, 2 pages, 40 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12747226&FileExtension=pdf&FileName=Evidence-Control-Form-Cylinder_Redacted-Rel.pdf - Damage photos (item 8, PDF, 6 pages, 2.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12058843&FileExtension=pdf&FileName=Damage%20Photos-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.