# NTSB WPR17LA094: Yakovlev YAK 52, N132MD, Porterville, CA, April 29, 2017 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: April 29, 2017, 10:15 local (17:15 UTC) - Place: Porterville, CA - Coordinates: 36.090831, -119.140274 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=36.0908&lon=-119.1403&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: 1 minor, 1 uninjured - Status: Completed, report November 6, 2018 - Report: Approved by Office Director - NTSB office: Western Pacific Region - Parties: Federal Aviation Administration - NTSB case key (mKey): 95083 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR17LA094 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/95083/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=95083 - Page: https://openairdocs.org/ntsb/WPR17LA094 ## Probable cause A partial loss of engine power due to contaminants in the fuel system that decreased the fuel flow, the source of which could not be determined. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Object/animal/substance: debris/dirt/foreign object](https://openairdocs.org/ntsb-findings/03022055): Environmental issues › Physical environment · Effect on equipment (probable cause); cases with it: [Yakovlev YAK 52, 1 case](https://openairdocs.org/ntsb-findings/03022055/cases.md?model=9830220), [All aircraft, 101 cases](https://openairdocs.org/ntsb-findings/03022055/cases.md) - [Fluids: fuel](https://openairdocs.org/ntsb-findings/01071010): Aircraft › Fluids/misc hardware · Fluid condition (probable cause); cases with it: [Yakovlev YAK 52, 1 case](https://openairdocs.org/ntsb-findings/01071010/cases.md?model=9830220), [All aircraft, 1,695 cases](https://openairdocs.org/ntsb-findings/01071010/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: [Yakovlev YAK 52, 2 cases](https://openairdocs.org/ntsb-events/342/sequence.md?model=9830220), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md) - [Landing: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Yakovlev YAK 52, 2 cases](https://openairdocs.org/ntsb-events/440/sequence.md?model=9830220), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) - [Landing: Nose over/nose down](https://openairdocs.org/ntsb-events/096); cases with it: [Yakovlev YAK 52, 1 case](https://openairdocs.org/ntsb-events/096/sequence.md?model=9830220), [All aircraft, 2,287 cases](https://openairdocs.org/ntsb-events/096/sequence.md) ## Analysis The airline transport pilot reported that, during a formation flight, the engine started to run rough. Unable to maintain level flight, the pilot detached from the formation to troubleshoot the problem. The pilot noted that there were about 29 gallons of useable fuel onboard and all other indications were normal. The engine continued to lose power, and about 500 ft above the ground, the pilot elected to land in a vineyard. During landing, the airplane touched down, came to an abrupt stop, nosed over, and came to rest inverted. Postaccident engine examination revealed small pieces of fabric in the fuel screen. In addition, some metal shavings and a small piece of metal were found in the fuel intake and carburetor inlet screen. The origins of the metal piece and shavings could not be determined. It is unlikely that the observed debris was enough to clog the fuel system; however, it is possible that there were other, non-observable pieces of debris in the fuel system that could have resulted in decreased fuel flow and the partial loss of engine power. ## Factual narrative On April 29, 2017, about 1015 Pacific daylight time, a Yakovlev Yak 52 airplane, N132MD, experienced a total loss of engine power and was substantially damaged during the off airport forced landing in a field near Porterville, California. The airline transport pilot sustained minor injuries and the one passenger was uninjured. The airplane was registered to and operated by the pilot as a 14 Code of Federal Regulations Part 91 personal flight. Visual meteorological conditions prevailed at the time of the accident, and no flight plan was filed. The local flight originated from Porterville Municipal airport (PTV) at 0935. The pilot reported that the purpose of the flight was to practice a mass formation flight. As planned, the pilot separated from the mass group as a formation of four to land. Shortly after separating from the larger formation, the engine started to run rough and intermittent. Unable to maintain level flight, the pilot detached from the four-airplane formation. He noted that 29 gallons of usable fuel was remaining, he checked the magnetos, ignition switch, generator, battery, and all indications were normal. The engine continued to lose power, and about 500 ft above the ground, he elected to land in a vineyard. During landing, the airplane touched down, came to an abrupt stop, and nosed over coming to rest inverted. During a postaccident examination of the airplane and engine by a mechanic and Federal Aviation Administration inspector, the spark plugs were removed and exhibited signatures consistent with normal wear and operation. The engine was rotated by hand and thumb compression was established in all cylinders. The oil screen was removed and was clear of debris. The fuel tanks were empty, and the fuel system was continuous throughout. The fuel screen exhibited some small pieces of unknown fabric. In addition, a small about of metal shavings from an unknown source and a small chunk of metal were found in the fuel intake and inlet screen. The carburetor was removed and examined. The carburetor throttle plate moved from stop to stop. The fuel metering section was heavily damaged and fracture separated; the needle valve moved freely. There were no signs of corrosion throughout. The fuel inlet screen was clear of debris with the exception of small metal shavings and a small chunk of metal. The origin of the metal pieces was not determined. ## Aircraft - Registration: [N132MD](https://openairdocs.org/deregistered/N132MD-2017-05-30), registration cancelled 2017-05-30, S/N 833802, built 1983 (OpenAirDocs) - Reported make and model: YAKOVLEV YAK 52 - Registry model: [Yakovlev YAK 52](https://openairdocs.org/model/yakovlev-yak-52) (registry code 9830220) (OpenAirDocs) - Registry engine: [Amateur-built UNKNOWN ENG](https://openairdocs.org/engine/amateur-built-unknown-eng) (registry code 99999) (OpenAirDocs) - Category: Airplane - Serial number: 833802 - Year built: 1983 - Airframe hours: 1734 - Engines: Vedeneyev M14P 360 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Annual, February 8, 2017, 21 hours before - Departed: PTV, Porterville, CA - Destination: PTV, Porterville, CA - Airport: PTV, Porterville Municipal Airport - Equipment: None ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 78; injuries: minor; commercial, airline transport; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 2, with waivers/limitations; last flight review April 17, 2017; seat: front; restraint: 3-point; flight hours: 26,144 total, 712 in this make and model, 18,824 as pilot in command, 21 in the last 90 days, 9 in the last 30 days, 0 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 210° at 7 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 66 °F, dew point 36 °F - Altimeter: 30.11 inHg - Observed at: PTV, 7 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 20170429024039A](https://openairdocs.org/incident/20170429024039A), Apr 29, 2017: Yakovlev YAK 52, Porterville, CA, Substantial damage. While in cruise flight engine lost power. Arcraft decened and crashed into a vinyard 6 miles n/w ptv airport. ## Docket (5 files) The files NTSB released with the investigation on July 17, 2018, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=95083. 3.2 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 1.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40465283&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Record of Email - Regarding Engine Examination (item 2, .PDF, 56 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40465284&FileExtension=.PDF&FileName=Record%20of%20Email%20-%20Regarding%20Engine%20Examination-Master.PDF - Carburetor Examination Observations (item 3, .PDF, 3 photos, 862 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40465285&FileExtension=.PDF&FileName=Carburetor%20Examination%20Observations-Master.PDF - Release of Aircraft Wreckage, NTSB Form 6120.15 (item 4, .PDF, 131 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40465286&FileExtension=.PDF&FileName=Release%20of%20Aircraft%20Wreckage,%20NTSB%20Form%206120.15-Master.PDF - Evidence Control Form - Carburetor (item 5, .PDF, 211 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40465287&FileExtension=.PDF&FileName=Evidence%20Control%20Form%20-%20Carburetor-Master.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.