# NTSB CEN16LA355: Republic RC3, N6490K, Post Oak, MO, August 30, 2016 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Limited investigation · Final report - Date: August 30, 2016, 08:55 local (13:55 UTC) - Place: Post Oak, MO - Coordinates: 38.569168, -93.746948 - Nearby events: https://openairdocs.org/map.md?lat=38.5692&lon=-93.7469&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: Serious injuries - Injuries: 1 serious - Status: Completed, report March 6, 2017 - Report: Approved by Office Director - NTSB office: Central Region - Parties: FAA FSDO - NTSB case key (mKey): 93957 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN16LA355 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/93957/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=93957 - Page: https://openairdocs.org/ntsb/CEN16LA355 ## Probable cause A partial loss of engine power due to low cylinder compression. Contributing to the loss of engine power was rust formation in the cylinders due to inactivity. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Engine (reciprocating)](https://openairdocs.org/ntsb-findings/01058500): Aircraft › Aircraft power plant · Fatigue/wear/corrosion (probable cause); cases with it: [Republic RC-3, 1 case](https://openairdocs.org/ntsb-findings/01058500/cases.md?model=3080202), [All aircraft, 497 cases](https://openairdocs.org/ntsb-findings/01058500/cases.md) - [Maintenance: scheduled/routine maintenance](https://openairdocs.org/ntsb-findings/02062010): Personnel issues › Task performance · Not specified (probable cause); cases with it: [Republic RC-3, 1 case](https://openairdocs.org/ntsb-findings/02062010/cases.md?model=3080202), [All aircraft, 320 cases](https://openairdocs.org/ntsb-findings/02062010/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: [Republic RC-3, 2 cases](https://openairdocs.org/ntsb-events/342/sequence.md?model=3080202), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md) - [Enroute: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Republic RC-3, 3 cases](https://openairdocs.org/ntsb-events/440/sequence.md?model=3080202), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) - [Emergency descent: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Republic RC-3, 7 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=3080202), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis The private pilot was conducting a local flight when the airplane's engine started to lose power. The pilot attempted a forced landing to a field; however, the airplane collided with trees. Examination of the airplane's engine noted that compression was low in all cylinders, and rust was present inside the cylinders. The airplane was not operated for about 4 years and had flown about 2 hours since being returned to service. The partial loss of engine power is consistent with a degradation in cylinder compression, and it is likely that rust formed in the engine during the time the airplane was not being used. ## Factual narrative On August 30, 2016, about 0855 central daylight time, a Republic RC3 amphibian airplane, N6490K, conducted a forced landing near Post Oak, Missouri. The private rated pilot received serious injuries and the airplane was substantially damaged during the accident. The airplane was registered to and operated by a private individual, under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed at the time. The pilot reported to the Federal Aviation Administration (FAA) inspector that the flight had just departed from a private airfield. During the flight, he felt the engine had lost power in a cylinder and tried to return to the airfield; however, he could not maintain altitude and elected to conduct a forced landing in a field. During the approach to the field, the airplane lost altitude and impacted trees, coming to rest nose low among several trees. An on-site examination of the airplane revealed substantial damage to the airplane's fuselage and wings, and fuel was present on site. An examination of the airplane's engine was conducted by the FAA inspector. The inspector noted that during a cylinder compression check of the engine, the No. 1, cylinder exhaust valve was not seating, and air was leaking past the piston rings on the other cylinders. He noted that the compressions on all the engine cylinders were low. He added that the cylinders appeared to have rust in them. He also reported that the pilot said the airplane sat for about 4 years before the airplane was returned service. The airplane had flown about two hours after being returned to service, before the accident flight. ## Aircraft - Registration: [N6490K](https://openairdocs.org/aircraft/N6490K), registered now, S/N 752, built 1947 (OpenAirDocs) - Reported make and model: REPUBLIC RC3 - Registry model: [Republic RC-3](https://openairdocs.org/model/republic-rc-3) (registry code 3080202) (OpenAirDocs) - Registry engine: [Franklin 6A8 series](https://openairdocs.org/engine/franklin-6a8-series) (registry code 27030, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 752 - Year built: 1947 - Engines: Franklin 215 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, August 10, 2016 - Departed: Post Oak, MO - Destination: Post Oak, MO ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 87; injuries: serious; private; airplane ratings: single-engine land, single-engine sea; medical: class 3, without waivers/limitations; last flight review September 15, 2015; seat: left; restraint: 3-point; flight hours: 2,730 total, 109.4 in this make and model, 10 in the last 90 days, 3 in the last 30 days, 3 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 70° at 4 knots - Visibility: 10 statute miles - Temperature: 75 °F, dew point 72 °F - Altimeter: 30.14 inHg - Observed at: KGLY ## 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 20160830015519A](https://openairdocs.org/incident/20160830015519A), Aug 30, 2016: Republic RC-3, Post Oak, MO, Substantial damage. On a cross country flight from rcm to the lake of the ozarks in Missouri, the pilot reported a loss of engine power. In an attempt to perform an emergency… ## Docket (3 files) The files NTSB released with the investigation on December 28, 2016, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=93957. 1.1 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 891 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40447886&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Inspector Statement (item 2, .PDF, 104 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40447887&FileExtension=.PDF&FileName=Inspector%20Statement-Master.PDF - Weather Reports and Records (item 3, .PDF, 109 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40447888&FileExtension=.PDF&FileName=Weather%20Reports%20and%20Records-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.