# NTSB CEN15LA414: Cessna 172P, N65191, Nutwood, IL, September 16, 2015 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: September 16, 2015, 10:30 local (15:30 UTC) - Place: Nutwood, IL - Coordinates: 39.08472, -90.556114 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=39.0847&lon=-90.5561&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Defining event: [Landing: Nose over/nose down](https://openairdocs.org/ntsb-events/096) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed, report January 21, 2016 - Report: Approved by Office Director - NTSB office: Central Region - Parties: Flight Standards District Office - NTSB case key (mKey): 91984 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN15LA414 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/91984/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=91984 - Page: https://openairdocs.org/ntsb/CEN15LA414 ## Probable cause A partial loss of engine power due to the undetected loosening of the four carburetor bolts that connect the throttle body to the bowl assembly. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Engine fuel and control: fuel control/carburetor](https://openairdocs.org/ntsb-findings/01057322): Aircraft › Aircraft power plant · Inadequate inspection (probable cause); cases with it: [Cessna 172P, 2 cases](https://openairdocs.org/ntsb-findings/01057322/cases.md?model=2072436), [All aircraft, 195 cases](https://openairdocs.org/ntsb-findings/01057322/cases.md) - [Maintenance: scheduled/routine maintenance](https://openairdocs.org/ntsb-findings/02062010): Personnel issues › Task performance · Maintenance personnel (probable cause); cases with it: [Cessna 172P, 3 cases](https://openairdocs.org/ntsb-findings/02062010/cases.md?model=2072436), [All aircraft, 320 cases](https://openairdocs.org/ntsb-findings/02062010/cases.md) - [Engine fuel and control: fuel control/carburetor](https://openairdocs.org/ntsb-findings/01057322): Aircraft › Aircraft power plant · Malfunction (probable cause); cases with it: [Cessna 172P, 2 cases](https://openairdocs.org/ntsb-findings/01057322/cases.md?model=2072436), [All aircraft, 195 cases](https://openairdocs.org/ntsb-findings/01057322/cases.md) - [Terrain](https://openairdocs.org/ntsb-findings/03021000): Environmental issues › Physical environment · Contributed to outcome; cases with it: [Cessna 172P, 3 cases](https://openairdocs.org/ntsb-findings/03021000/cases.md?model=2072436), [All aircraft, 267 cases](https://openairdocs.org/ntsb-findings/03021000/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Maneuvering: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342); cases with it: [Cessna 172P, 9 cases](https://openairdocs.org/ntsb-events/342/sequence.md?model=2072436), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md) - [Landing: Nose over/nose down](https://openairdocs.org/ntsb-events/096) (defining event); cases with it: [Cessna 172P, 18 cases](https://openairdocs.org/ntsb-events/096/sequence.md?model=2072436), [All aircraft, 2,287 cases](https://openairdocs.org/ntsb-events/096/sequence.md) ## Analysis The pilot reported that, while maneuvering the airplane at 3,000 ft mean sea level, the engine lost partial power and began running roughly. After unsuccessfully attempting to regain normal engine power, the pilot executed a forced landing into a field, during which the airplane nosed over. Postaccident examination of the carburetor revealed a gap between the throttle body and bowl assembly, and all four bolts connecting the throttle body to the bowl assembly were found loose. Both the engine and carburetor manufacturers had previously issued service bulletins (SB) regarding possible leakage between the bowl assembly and throttle body, likely due to loose bowl to throttle body screws. The SBs recommended inspecting the carburetor screws every 100 hours of engine operation. The last 100-hour inspection of the engine occurred 89 hours before the accident. ## Factual narrative On September 16, 2015, about 1030 central daylight time, a Cessna 172P airplane, N65191, was substantially damaged during a forced landing near Nutwood, Illinois. The pilot sustained minor injuries. The airplane was registered to and operated by Sixninethreeone LLC under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. Day visual meteorological conditions prevailed for the local flight, which departed from the St. Charles County Smartt Airport (SET), St. Charles, Missouri, about 1000. While maneuvering at 3,000 feet msl, the pilot stated the engine lost partial power and ran rough. After unsuccessfully attempting to regain normal engine power, the pilot executed a forced landing into a field. The airplane nosed over during rollout and damaged the right wing. During post-accident examination of the carburetor, Federal Aviation Administration personnel noted a gap was present between the throttle body and bowl assembly. It was also noted that the four bolts which connect the throttle body to the bowl assembly were loose. Marvel Schebler Service Bulletin (SB)-17, dated August 12, 2010, with a subject of, "Body to Bowl Fuel Leaks", directs an inspection of the carburetor every 100 hours of engine operation. The SB indicates reports of loose body to bowl joints, with resulting leakage past the gasket between the bowl and throttle body. The SB further indicates that the leakage may be accompanied by loose bowl to throttle body screws. The compliance section of the SB indicates to visually inspect the carburetor for evidence of looseness of the bowl relative to the throttle body. The SB goes on to say that if looseness is detected, the carburetor must be removed from the engine and to inspect the threaded holes in the bowl and screws to assure the threads are serviceable. A new gasket and lock tab washers are to be installed, and the carburetor is to be tested in accordance with the appropriate service manual. Lycoming mandatory SB-366B, dated April 18, 2008, also directs an inspection of the carburetor every 100 hours of engine operation. The compliance section of the Lycoming SB is parallel to the Marvel Schebler SB. The last 100 hour inspection of the engine occurred 89 hours prior to the accident. The director of maintenance stated that maintenance personnel were aware of the Lycoming SB and were checking carburetor screws for looseness, but were not documenting accomplishment of the SB in engine logbooks. ## Aircraft - Registration: [N65191](https://openairdocs.org/aircraft/N65191), registered now, S/N 17275705, built 1982 (OpenAirDocs) - Reported make and model: CESSNA 172P - Registry model: [Cessna 172P](https://openairdocs.org/model/cessna-172p) (registry code 2072436) (OpenAirDocs) - Registry engine: [Lycoming 0-320 series](https://openairdocs.org/engine/lycoming-0-320-series) (registry code 41508, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 17275705 - Year built: 1982 - Airframe hours: 8071 - Engines: LYCOMING O-320 SERIES 160 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Operator: Sixninethreeonea LLC - Registered owner: Sixninethreeonea LLC - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, July 30, 2015, 89 hours before - Departed: KSET, St Charles, MO - Destination: KSET, St Charles, MO - Equipment: Stall warning system ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 66; injuries: minor; private; airplane ratings: single-engine land; medical: class 3, with waivers/limitations; last flight review September 12, 2014; seat: left; restraint: 3-point; flight hours: 300 total, 300 in this make and model, 167 as pilot in command, 5 in the last 90 days, 2 in the last 30 days, 0 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 160° at 6 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 79 °F, dew point 59 °F - Altimeter: 30.20 inHg - Observed at: KSET, 11 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 20150916014639A](https://openairdocs.org/incident/20150916014639A), Sep 16, 2015: Cessna 172P, Fieldon, IL, Substantial damage. The aircraft engine began to run rough and the RPM dropped to 1500 in cruise flight so the pilot circled open fields and when he couldn't keep sufficient… ## Docket (4 files) The files NTSB released with the investigation on December 7, 2015, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=91984. 7.1 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 5.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40434600&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Photos of Carburetor Taken During FAA Engine Exam (item 2, .PDF, 2 photos, 1.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40434601&FileExtension=.PDF&FileName=Photos%20of%20Carburetor%20Taken%20During%20FAA%20Engine%20Exam-Master.PDF - Marvel-Schebler Service Bulletin for Carburetor (item 3, .PDF, 154 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40434602&FileExtension=.PDF&FileName=Marvel-Schebler%20Service%20Bulletin%20for%20Carburetor-Master.PDF - Lycoming Service Bulletin for Carburetor (item 4, .PDF, 379 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40434603&FileExtension=.PDF&FileName=Lycoming%20Service%20Bulletin%20for%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.