# NTSB CEN14LA412: Enstrom F 28F, N213BL, Tomah, WI, August 7, 2014 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Limited investigation · Final report - Date: August 7, 2014, 09:46 local (14:46 UTC) - Place: Tomah, WI - Coordinates: 43.980323, -90.500907 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=43.9803&lon=-90.5009&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering-low-alt flying: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) - Highest injury: Serious injuries - Injuries: 1 serious - Status: Completed, report January 14, 2015 - Report: Approved by Office Director - NTSB office: Central Region - Parties: FAA Flight Standards - NTSB case key (mKey): 89828 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN14LA412 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/89828/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=89828 - Page: https://openairdocs.org/ntsb/CEN14LA412 ## Probable cause A loss of engine power due to the malfunction of the No. 4 cylinder intake valve. ## 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 · Malfunction (probable cause); cases with it: [Enstrom F-28F, 2 cases](https://openairdocs.org/ntsb-findings/01058530/cases.md?model=3300412), [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. - [Maneuvering-low-alt flying: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) (defining event); cases with it: [Enstrom F-28F, 1 case](https://openairdocs.org/ntsb-events/342/sequence.md?model=3300412), [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: [Enstrom F-28F, 2 cases](https://openairdocs.org/ntsb-events/440/sequence.md?model=3300412), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) ## Analysis The pilot felt a vibration in the cyclic control and he stated that the engine was running irregularly as he neared the intended application field on the agricultural application flight. He immediately elected to execute a precautionary landing to a cornfield; the corn crop was about 10 feet tall at the time. During the landing, the landing skids collapsed, and the tailboom was severed by a main rotor blade. A postaccident examination of the engine revealed that the No. 4 cylinder did not exhibit compression during crankshaft rotation. Further examination of the No. 4 cylinder revealed that the intake valve did not seat properly; a gap of about 0.015 inch existed when the valve should have been fully seated. Linear scoring was observed on the valve stem, and debris consistent with valve guide material was also recovered upon removal of the valve. No other anomalies with respect to the engine were observed. The engine had accumulated about 831 hours since overhaul. The helicopter maintenance records did not contain a record of any unresolved maintenance issues. ## Factual narrative On August 7, 2014, about 0946 central daylight time, an Enstrom F-28F helicopter, N213BL, was substantially damaged when the pilot executed a precautionary landing in a cornfield after experiencing engine difficulties near Tomah, Wisconsin. The pilot was seriously injured. The helicopter was registered to and operated by Paul Peterson Aviation LLC under the provisions of 14 Code of Federal Regulations Part 137 as an aerial application flight. Visual meteorological conditions prevailed for the flight, which was not operated on a flight plan. The local flight originated from the loading site about one-half mile from the accident site.The pilot's departure from the loading site on the third application flight of the morning proceeded without incident. However, about one-half mile from the planned application field, the pilot reportedly felt a vibration in the cyclic control and experienced an "irregular" running engine. He immediately elected to execute a precautionary landing to a corn field; the corn crop was approximately 10 feet tall at the time. During the landing, the landing skids collapsed and the tailboom was severed by a main rotor blade. A portion of the tail rotor drive shaft was separated from the airframe. Separation of the drive shaft was consistent with a main rotor strike. The tail rotor transmission separated into two sections; the appearance of the fracture surface was consistent with an overstress failure. The postaccident examination did not reveal any preimpact anomalies with respect to the flight control system and rotor drive system. Examination of the engine revealed that the no. 4 cylinder did not exhibit compression during crankshaft rotation. Further examination of the No. 4 cylinder determined that the intake valve was not seating properly; a gap of approximately 0.015 inch existed when the valve should have been fully seated. Linear scoring were observed on the valve stem. Debris consistent with valve guide material was also recovered on removal of the valve. No other anomalies with respect to the engine were observed. The accident helicopter was purchased by the operator on June 4, 2014. The aircraft was issued a restricted category, special airworthiness certificate for agriculture operations on July 25, 2014. The operator reported a total airframe time of 2,385.1 hours at the time of the accident. The most recent annual inspection was completed in December 2013 at 2,327.4 hours. The helicopter was powered by a 225-horsepower Lycoming HIO-360-F1AD fuel-injected, reciprocating engine. Maintenance records indicated that the engine was overhauled in March 2006. At the time of the accident, the engine had accumulated about 831.2 hours since overhaul, with about 57.7 hours of that time since the annual inspection. The most recent engine maintenance entry was dated August 4, 2014, and consisted of replacement of the spark plugs. The helicopter maintenance records did not contain a record of any unresolved maintenanceissues. ## Aircraft - Registration: [N213BL](https://openairdocs.org/deregistered/N213BL-2015-04-22), registration cancelled 2015-04-22, S/N 803, built 1995 (OpenAirDocs) - Reported make and model: ENSTROM F 28F - Registry model: [Enstrom F-28F](https://openairdocs.org/model/enstrom-f-28f) (registry code 3300412) (OpenAirDocs) - Registry engine: [Lycoming HIO-360-F1AD](https://openairdocs.org/engine/lycoming-hio-360-f1ad) (registry code 41896, reciprocating) (OpenAirDocs) - Category: Helicopter - Serial number: 803 - Year built: 1995 - Airframe hours: 2385.1 - Engines: Lycoming HIO-360-F1AD 225 horsepower reciprocating - Damage: Substantial damage - Flight: Aerial application, Part 137 - Operator: Paul Peterson Aviation LLC - Registered owner: Paul Peterson Aviation LLC - Airworthiness certificate: Special, Restricted (Special) - Last inspection: Annual, December 2, 2013 - Departed: PVT, Tomah, WI - Destination: PVT, Tomah, WI ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 70; injuries: serious; airline transport; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane, helicopter; medical: class 2, with waivers/limitations; seat: left; restraint: 3-point; flight hours: 18,000 total, 250 in this make and model, 12,000 as pilot in command, 40 in the last 90 days, 40 in the last 30 days, 9 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 110° at 7 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 77 °F, dew point 54 °F - Altimeter: 30.12 inHg - Observed at: CMY, 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 20140807014129A](https://openairdocs.org/incident/20140807014129A), Aug 7, 2014: Enstrom F-28F, Tomah, WI, Substantial damage. August 7, 2014 N213BL an Enstrom F28-F helicopter crash landed in a corn field at 20526 glider ave. in Tomah Wisconsin. The helicopter was conducting aerial… ## Docket (11 files) The files NTSB released with the investigation on November 13, 2014, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=89828. 26.2 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 2.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40418940&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Accident Site Diagram (item 2, .PDF, 442 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40418941&FileExtension=.PDF&FileName=Accident%20Site%20Diagram-Master.PDF - Summary of Engine Examination (item 3, .PDF, 270 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40418942&FileExtension=.PDF&FileName=Summary%20of%20Engine%20Examination-Redacted.PDF - Airframe Maintenance Logbook (Excerpts) (item 4, .PDF, 2.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40418943&FileExtension=.PDF&FileName=Airframe%20Maintenance%20Logbook%20(Excerpts)-Redacted.PDF - Engine Maintenance Logbook (Excerpts) (item 5, .PDF, 1.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40418944&FileExtension=.PDF&FileName=Engine%20Maintenance%20Logbook%20(Excerpts)-Redacted.PDF - AD Listing (item 6, .PDF, 604 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40418945&FileExtension=.PDF&FileName=AD%20Listing-Redacted.PDF - Aircraft Component Log (item 7, .PDF, 178 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40418946&FileExtension=.PDF&FileName=Aircraft%20Component%20Log-Redacted.PDF - Aircraft Weight and Balance (item 8, .PDF, 165 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40418947&FileExtension=.PDF&FileName=Aircraft%20Weight%20and%20Balance-Redacted.PDF - FAA Registration Records (Excerpts) (item 9, .PDF, 6.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40418948&FileExtension=.PDF&FileName=FAA%20Registration%20Records%20(Excerpts)-Redacted.PDF - FAA Airworthiness Records (Excerpts) (item 10, .PDF, 13.4 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40418952&FileExtension=.PDF&FileName=FAA%20Airworthiness%20Records%20(Excerpts)-Redacted.PDF - Weather Documentation (item 11, .PDF, 105 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40418955&FileExtension=.PDF&FileName=Weather%20Documentation-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.