# NTSB CEN21LA408: Cessna 150, N50055, Heavener, OK, August 15, 2021 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Class 3 · Limited · Final report - Date: August 15, 2021, 17:00 local (22:00 UTC) - Place: Heavener, OK - Coordinates: 34.776655, -94.515596 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=34.7767&lon=-94.5156&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: Central Region - Parties: FAA FSDO - NTSB case key (mKey): 103824 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN21LA408 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/103824/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=103824 - Page: https://openairdocs.org/ntsb/CEN21LA408 ## Probable cause A total loss of engine power due to the failure of the No. 2 cylinder exhaust valve for reasons that could not be determined. ## 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 · Failure; cases with it: [Cessna 150H, 2 cases](https://openairdocs.org/ntsb-findings/01058530/cases.md?model=2071818), [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 150H, 10 cases](https://openairdocs.org/ntsb-events/341/sequence.md?model=2071818), [All aircraft, 3,820 cases](https://openairdocs.org/ntsb-events/341/sequence.md) ## Analysis While in cruise flight, the airplane’s engine began to run rough. As the pilot was attempting to restore engine power, the engine experienced a total loss of engine power. The pilot performed a forced landing to a field and the airplane collided with terrain. A postaccident examination of the engine revealed that the No. 2 cylinder exhaust valve had failed, damaging the piston head and resulting in a loss of engine power. Machining of the fracture surfaces precluded determining the mode of failure. The engine was last overhauled about 32 years before the accident with just over 1,030 hours logged on the components. The engine manufacturer recommends an overhaul every 1,800 hours or 12 years. ## Factual narrative On August 15, 2021, about 1700 central daylight time, a Cessna 150H airplane, N50055, was substantially damaged when it was involved in an accident near Heavener, Oklahoma. The pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that while in cruise flight to his destination, the airplane’s engine began to run rough. As he attempted to troubleshoot the rough running engine, the engine stopped producing power. The pilot performed a forced landing to a field. During the landing, the airplane collided with a dirt mound and trees. Substantial damage was sustained to the fuselage and wings. A postaccident examination of the engine revealed the No. 2 cylinder exhaust valve was fractured with associated damage on the cylinder piston. Machining of the valve surfaces precluded analyzing the mode of failure. A review of maintenance logbooks revealed that the engine was last overhauled on October 17, 1988, at a tachometer time of 2,438 hours. A logbook entry recorded the work conducted to include replacement of the exhaust valves. The most recent inspection was a 100-hour type conducted on April 1, 2021, with a tachometer time of 3,469.17 hours. Continental Motors Service Information Letter SIL-98-9C, revised July 17, 2017, provides time limits between major overhauls on their engines. For the accident engine’s serial number range, overhauls should take place every 1,800 hours or 12 years. ## Aircraft - Registration: [N50055](https://openairdocs.org/deregistered/N50055-2022-12-24), registration cancelled 2022-12-24, S/N 15069042, built 1968 (OpenAirDocs) - Reported make and model: CESSNA 150 (H) - Registry model: [Cessna 150H](https://openairdocs.org/model/cessna-150h) (registry code 2071818) (OpenAirDocs) - Registry engine: [Continental 0-200 series](https://openairdocs.org/engine/continental-0-200-series) (registry code 17020, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 15069042 - Year built: 1968 - Airframe hours: 3469.2 - Engines: Continental O-200A 100 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Registered owner: Damianov Venko D - Airworthiness certificate: Standard, Utility - Last inspection: 100 hour, April 1, 2021 - Departed: KTKI, McKinney, TX - Destination: KBDQ, Morriltton, AR - Airport: n/a - Equipment: ADS-B ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 47; injuries: minor; private; airplane ratings: single-engine land; medical: class 2, without waivers/limitations; seat: left; flight hours: 201 total, 160 in this make and model, 86 as pilot in command ## Weather - Conditions: Visual (VMC), Day - Wind: 70° at 4 knots - Visibility: 10 statute miles - Lowest ceiling: 8,000 ft overcast - Temperature: 75 °F, dew point 73 °F - Altimeter: 30.03 inHg - Observed at: KMEZ, 21 nm away - METAR: METAR KMEZ 152215Z AUTO 07004KT 10SM SCT060 OVC080 24/23 A3003 RMK AO2 LTG DSNT S THRU NW= ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Incident 20210815014349I](https://openairdocs.org/incident/20210815014349I), Aug 15, 2021: Cessna 150H, Heavener, OK, Minor damage. During cruse flight the aircraft engine began sputtering. Pilot applied corrective action to regain proper engine operation. Aircraft engine stopped in air.… ## Docket (3 files) The files NTSB released with the investigation on December 29, 2022, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=103824. 15.0 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 9 pages, 2.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14915075&FileExtension=pdf&FileName=NTSB%20FORM%206120%20CEN21LA408_Redacted-Rel.pdf - Photos (item 2, PDF, 6 pages, 6 photos, 11.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12992895&FileExtension=pdf&FileName=Photos%206_Redacted-Rel.pdf - Engine examination (item 3, PDF, 3 pages, 2 photos, 1.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12992905&FileExtension=pdf&FileName=Examination%20Summary%20--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.