# NTSB CEN20LA051: Enstrom F28, N57SJ, Danbury, TX, December 31, 2019 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 3 · Limited · Final report - Date: December 31, 2019, 13:30 local (19:30 UTC) - Place: Danbury, TX - Coordinates: 29.243888, -95.333053 - Nearby events: https://openairdocs.org/map.md?lat=29.2439&lon=-95.3331&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Central Region - Parties: FAA - Houston FSDO - NTSB case key (mKey): 100750 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN20LA051 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/100750/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=100750 - Page: https://openairdocs.org/ntsb/CEN20LA051 ## Probable cause The failure of the engine's No.3 intake valve resulting is a loss of engine power and a rollover following the autorotation to soft ground. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Engine (reciprocating): recip engine power section](https://openairdocs.org/ntsb-findings/01058520): Aircraft › Aircraft power plant · Failure (probable cause); cases with it: [Enstrom F-28A, 1 case](https://openairdocs.org/ntsb-findings/01058520/cases.md?model=3300406), [All aircraft, 233 cases](https://openairdocs.org/ntsb-findings/01058520/cases.md) - [Terrain: wet/muddy terrain](https://openairdocs.org/ntsb-findings/03021035): Environmental issues › Physical environment · Contributed to outcome (probable cause); cases with it: [Enstrom F-28A, 1 case](https://openairdocs.org/ntsb-findings/03021035/cases.md?model=3300406), [All aircraft, 110 cases](https://openairdocs.org/ntsb-findings/03021035/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) (defining event); cases with it: [Enstrom F-28A, 1 case](https://openairdocs.org/ntsb-events/342/sequence.md?model=3300406), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md) - [Autorotation: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Enstrom F-28A, 2 cases](https://openairdocs.org/ntsb-events/440/sequence.md?model=3300406), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) - [Landing: Roll over](https://openairdocs.org/ntsb-events/097); cases with it: [Enstrom F-28A, 1 case](https://openairdocs.org/ntsb-events/097/sequence.md?model=3300406), [All aircraft, 261 cases](https://openairdocs.org/ntsb-events/097/sequence.md) ## Analysis The student pilot turned the helicopter onto the crosswind leg of the traffic pattern during a training flight when the engine suddenly began to run rough and lost partial power. The flight instructor took the controls and executed an autorotation into a clearing. The skids of the helicopter sank into the soft mud, the rotor blades contacted the ground, and the helicopter rolled onto its side. Examination of the engine revealed that a portion of the No. 3 cylinder intake valve had broken off and migrated into the No. 1 cylinder, where it lodged between the No. 1 cylinder's intake valve and seat, holding that valve in the open position and resulting in the partial loss of engine power. ## Factual narrative On December 31, 2019, about 1415 central standard time, an Enstrom F28A helicopter, N57SJ, sustained substantial damage when it nosed over during a forced landing following a partial loss of engine power. During the nose-over, the tailboom was separated and the main rotor system and fuselage were damaged. The student pilot and flight instructor were not injured. The helicopter was registered to and operated by a private individual under the provisions of Title 14 Code of federal Regulations Part 91 as an instructional flight. Visual meteorological conditions prevailed for the flight, which was not operated on a flight plan. The local flight originated from the Salaika Aviation Airport (07TA), Danbury, Texas, at an unconfirmed time. The certificated flight instructor stated that he and his student had departed for a second pattern during a training mission. After the helicopter made the turn onto the crosswind leg of the traffic pattern the engine suddenly began to run rough and had lost a lot of power. He took the controls and executed an autorotation into a clearing, flared and touched down. The skids of the helicopter sunk into the soft mud, the rotor blades contacted the ground, and the helicopter rolled onto its side. The operator reported that examination of the engine after the accident revealed that a portion of the intake valve for the No. 3 cylinder had broken off and had migrated into the No. 1 cylinder where it lodged between the No. 1 intake valve and seat, holding that valve in the open position. ## Aircraft - Registration: [N57SJ](https://openairdocs.org/deregistered/N57SJ-2021-03-24), registration cancelled 2021-03-24, S/N 278, built 1975 (OpenAirDocs) - Reported make and model: Enstrom F28 (A) - Registry model: [Enstrom F-28A](https://openairdocs.org/model/enstrom-f-28a) (registry code 3300406) (OpenAirDocs) - Registry engine: [Lycoming I0360 series](https://openairdocs.org/engine/lycoming-i0360-series) (registry code 41515, reciprocating) (OpenAirDocs) - Category: Helicopter - Serial number: 278 - Year built: 1975 - Airframe hours: 3632 - Engines: Lycoming HIO-360-C1A 205 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, September 4, 2019 - Departed: 07TA, Danbury, TX - Destination: 07TA, Danbury, TX - Airport: 07TA, Salaika Aviation - Equipment: Handheld GPS, Electronic primary flight display, ADS-B, Satellite tracking device ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 37; injuries: none; commercial, flight instructor; airplane ratings: single-engine land; medical: class 2, without waivers/limitations; last flight review August 23, 2018; seat: right; restraint: lap only; flight hours: 4,902 total, 4,000 in this make and model, 4,700 as pilot in command, 122 in the last 90 days, 36 in the last 30 days, 2 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 90° at 3 knots - Visibility: 10 statute miles - Lowest ceiling: 7,500 ft overcast - Temperature: 59 °F, dew point 28 °F - Altimeter: 30.20 inHg - Observed at: LBX ## 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 20191231022339A](https://openairdocs.org/incident/20191231022339A), Dec 31, 2019: Enstrom F-28A, Danbury, TX, Destroyed. Aircraft experienced power loss while flying approximately 100 feet above tree tops pilot initiated an autorotation landing when the aircraft landed the skids… ## Docket (2 files) The files NTSB released with the investigation on July 31, 2020, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=100750. 664 KB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 610 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40485684&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Record of Conversation (Pilot's father) (item 2, .PDF, 54 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40485685&FileExtension=.PDF&FileName=Record%20of%20Conversation%20(Pilot%27s%20father)-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.