# NTSB WPR18LA148: Cessna 152, N152GB, Hillsboro, OR, May 26, 2018 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 3 · Limited · Final report - Date: May 26, 2018, 09:35 local (16:35 UTC) - Place: Hillsboro, OR - Coordinates: 45.550277, -122.956947 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=45.5503&lon=-122.9569&mi=10 - Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping) - Defining event: [Approach-VFR go-around: 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: Federal Aviation Administration - NTSB case key (mKey): 97326 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR18LA148 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/97326/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=97326 - Page: https://openairdocs.org/ntsb/WPR18LA148 ## Probable cause The partial loss of engine power during a go-around due to the loose copper electrode finger inside the left magneto. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Ignition system: magneto/distributor](https://openairdocs.org/ntsb-findings/01057414): Aircraft › Aircraft power plant · Failure (probable cause); cases with it: [Cessna 152, 4 cases](https://openairdocs.org/ntsb-findings/01057414/cases.md?model=2071835), [All aircraft, 101 cases](https://openairdocs.org/ntsb-findings/01057414/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Approach-VFR go-around: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) (defining event); cases with it: [Cessna 152, 21 cases](https://openairdocs.org/ntsb-events/342/sequence.md?model=2071835), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md) - [Approach-VFR go-around: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Cessna 152, 35 cases](https://openairdocs.org/ntsb-events/440/sequence.md?model=2071835), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) - [Landing-landing roll: Nose over/nose down](https://openairdocs.org/ntsb-events/096); cases with it: [Cessna 152, 37 cases](https://openairdocs.org/ntsb-events/096/sequence.md?model=2071835), [All aircraft, 2,287 cases](https://openairdocs.org/ntsb-events/096/sequence.md) ## Analysis While conducting takeoffs and landings during an instructional flight, the student pilot initiated a go-around. Shortly thereafter, the engine began to run rough and lost partial power. The instructor attempted to troubleshoot the engine, but was unable to restore engine power, and initiated a forced landing to a grass area beyond the end of the runway, during which the airplane nosed over. Examination of the engine revealed that the left magneto was producing spark randomly across its four posts. Internal examination of that magneto revealed that the distributor gear was intact; however, the copper electrode finger was found displaced from the plastic gear assembly. A service bulletin issued by the magneto manufacturer about three years before the accident stated that some units contained distributor gears that exhibited loose electrode fingers, the symptoms of which included "unusual RPM drop during magneto check, difficulty starting, and/or rough running engines." A separate service bulletin issued 38 years before the accident specified that the magnetos should be inspected internally every 500 hours. The operator reported that, at the time of the accident, the magneto had accumulated 402.7 hours since its most recent internal inspection. The operator further reported they conducted internal inspections of the magnetos every 750 hours. It is likely that the loose copper electrode finger resulted in the partial loss of engine power during the go-around. ## Factual narrative On May 26, 2018, about 0935 Pacific daylight time, a Cessna 152 airplane, N152GB, sustained substantial damage when it was involved in an accident near Hillsboro, Oregon. The flight instructor and student pilot were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 instructional flight. The instructor reported that during their sixth stop-and-go landing, the student initiated a go-around. A short time later, the engine began to make a "plugging sound" and the instructor took control of the airplane. He adjusted the throttle, as the engine was "still making weird sounds," and informed the tower controller that the airplane was losing engine power. As the airplane neared the departure end of the runway, at an altitude of about 200 ft above ground level, the instructor initiated a forced landing. The airplane touched down in the grass area beyond the departure end of the runway and nosed over. Examination of the airplane by a Federal Aviation Administration (FAA) inspector revealed substantial damage to both wings. The airplane was recovered to a secure location for further examination. The carburetor was replaced, and an external fuel source attached to facilitate an engine run. During the engine run, the engine lost power when the left magneto was selected. No additional evidence of any mechanical anomalies was observed, and the magnetos were removed for further examination. Examination of the left magneto revealed that when the drive shaft was rotated, spark was produced on each post in a random order. The magneto was disassembled and examined internally. The distributor gear was intact; however, the copper electrode finger was found displaced from the plastic gear assembly. The remainder of the internal components were unremarkable. The right magneto produced spark in firing order when the drive shaft was rotated by hand. The magneto was disassembled, and all internal parts were unremarkable. Slick Service Bulletin SB2-80C, issued in February 1980 and last revised in April 1991, specified that all 4300-series magnetos should be inspected externally every 100 hours, and internally every 500 hours. Slick Bulletin SB1-15A, originally published in July 2015 and revised in November 2018, outlined the potential for decreased service life of 4-cylinder magneto distributor gear assemblies, including the 4301 magneto. The service bulletin stated in part that, "…some of the returned products contained distributor gears exhibiting loosening of the electrode finger." In addition, the service bulletin stated that "…typical symptoms are unusual RPM drop during magneto check, difficulty starting, and/or rough running engines." Compliance with the service bulletin included replacement of the distributor gears equipped with a copper electrode. The operator reported that the left magneto was installed on the engine in June 2016, at a time since overhaul of 1,602.2 hours. At the time of the accident, the left magneto had atotal time of 2,632.7 hours, and 402.7 hours since its most recent inspection. The operator further reported that they conducted internal inspections of the magnetos every 750 hours. ## Aircraft - Registration: [N152GB](https://openairdocs.org/aircraft/N152GB), registered now, S/N 15279546, built 1977 (OpenAirDocs) - Reported make and model: CESSNA 152 (NO SERIES) - Registry model: [Cessna 152](https://openairdocs.org/model/cessna-152) (registry code 2071835) (OpenAirDocs) - Registry engine: [Lycoming 0-235 series](https://openairdocs.org/engine/lycoming-0-235-series) (registry code 41505, 4 cycle) (OpenAirDocs) - Category: Airplane - Serial number: 15279546 - Year built: 1977 - Airframe hours: 10267.4 - Engines: LYCOMING O-235 110 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Operator: Hillsboro Aero Academy LLC - Registered owner: Hillsboro Aero Academy LLC - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, April 27, 2018, 4.8 hours before - Departed: HIO, Hillsboro, OR - Destination: HIO, Hillsboro, OR - Airport: HIO, Portland-Hillsboro, runway 31R, 3,600 × 60 ft, asphalt - Equipment: Stall warning system ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 29; injuries: none; student; medical: class 3, without waivers/limitations; seat: left; restraint: 3-point; flight hours: 41 total, 41 in this make and model, 7 as pilot in command, 41 in the last 90 days, 16 in the last 30 days - Flight instructor; age 33; injuries: none; flight instructor; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 2, without waivers/limitations; seat: right; restraint: 3-point; flight hours: 447 total, 167 in this make and model, 369 as pilot in command, 149 in the last 90 days, 49 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: 210° at 5 knots - Visibility: 10 statute miles - Lowest ceiling: 4,300 ft overcast - Temperature: 55 °F, dew point 45 °F - Altimeter: 30.19 inHg - Observed at: KHIO, 1 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 20180526005969A](https://openairdocs.org/incident/20180526005969A), May 26, 2018: Cessna 152, Hillsboro, OR, Substantial damage. A flight instructor and a student were practicing touch and go landings on runway 31R at Hillsboro airport. They flight instructor stated he had made 2… ## Docket (5 files) The files NTSB released with the investigation on March 10, 2021, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=97326. 7.3 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 15 pages, 6.4 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=7801532&FileExtension=pdf&FileName=61%20test%2020_Redacted-Rel.pdf - Record of conversation - FAA inspector (item 2, PDF, 1 page, 71 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=7801698&FileExtension=pdf&FileName=FAA%20Roc-Rel.pdf - NTSB magneto examination report (item 3, PDF, 3 pages, 3 photos, 690 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=7801288&FileExtension=pdf&FileName=magneto%20exam-Rel.pdf - Magneto service times provided by the operator (item 4, PDF, 1 page, 42 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=7800342&FileExtension=pdf&FileName=N152GB%20Magneto%20Times-Rel.pdf - Evidence control form - magnetos (item 5, PDF, 1 page, 59 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=7802098&FileExtension=pdf&FileName=WPR18la148%20iic%20001_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.