# NTSB WPR12LA111: Enstrom F28, N51727, Kalispell, MT, February 20, 2012 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: February 20, 2012, 10:30 local (17:30 UTC) - Place: Kalispell, MT - Coordinates: 48.310554, -114.256111 - Nearby events: https://openairdocs.org/map.md?lat=48.3106&lon=-114.2561&mi=10 - Phase of flight: [Emergency descent](https://openairdocs.org/ntsb-phases/600) (OpenAirDocs' grouping) - Defining event: [Autorotation: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report February 14, 2013 - Report: Approved by Office Director - NTSB office: Western Pacific Region - Parties: Federal Aviation Administration - NTSB case key (mKey): 82928 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR12LA111 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/82928/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=82928 - Page: https://openairdocs.org/ntsb/WPR12LA111 ## Probable cause A total loss of engine power for reasons that could not be determined because postaccident examination did not reveal any anomalies that would have precluded normal operation. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Not determined](https://openairdocs.org/ntsb-findings/05000000): Not determined › Not determined · Unknown/Not determined (probable cause); cases with it: [Enstrom F-28C, 2 cases](https://openairdocs.org/ntsb-findings/05000000/cases.md?model=3300407), [All aircraft, 2,247 cases](https://openairdocs.org/ntsb-findings/05000000/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Autorotation: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) (defining event); cases with it: [Enstrom F-28C, 3 cases](https://openairdocs.org/ntsb-events/341/sequence.md?model=3300407), [All aircraft, 3,820 cases](https://openairdocs.org/ntsb-events/341/sequence.md) - [Emergency descent: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Enstrom F-28C, 3 cases](https://openairdocs.org/ntsb-events/440/sequence.md?model=3300407), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) - [Autorotation: Hard landing](https://openairdocs.org/ntsb-events/092); cases with it: [Enstrom F-28C, 6 cases](https://openairdocs.org/ntsb-events/092/sequence.md?model=3300407), [All aircraft, 2,102 cases](https://openairdocs.org/ntsb-events/092/sequence.md) - [Landing-landing roll: Loss of control on ground](https://openairdocs.org/ntsb-events/230); cases with it: [Enstrom F-28C, 2 cases](https://openairdocs.org/ntsb-events/230/sequence.md?model=3300407), [All aircraft, 4,585 cases](https://openairdocs.org/ntsb-events/230/sequence.md) ## Analysis The flight instructor reported that the helicopter experienced a loss of engine power after the student initiated a practice autorotation about 650 feet above ground level. The flight instructor then assumed control of the helicopter for an emergency landing. However, the helicopter touched down short of the runway, became airborne again, rotated 180 degrees to the left, and landed on the taxiway with the main rotor spinning down. During the postaccident examination, the engine started and ran with no evidence of preaccident mechanical malfunctions or failures that would have precluded normal operation. The cause of the reported loss of engine power could not be duplicated. ## Factual narrative On February 20, 2012, about 1030 mountain standard time, an Enstrom F-28C helicopter, N51727, was substantially damaged following a loss of engine power and impact with terrain at the Kalispell City Airport (S27), Kalispell, Montana. The certified flight instructor and pilot receiving instruction were not injured. Visual meteorological conditions prevailed for the local instructional flight, which was being operated in accordance with 14 Code of Federal Regulations (CFR) Part 91, and a flight plan was not filed. The flight departed S27 about 0940. In a statement provided to the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), the certified flight instructor reported that on the fourth practice autorotation of the morning, the student initiated a 180-degree autorotation from about 650 feet above ground level (agl). The instructor stated that at the 90-degree point he recognized that the engine had failed, at which time he took full control of the helicopter and initiated an [emergency descent]. After touching down at a speed of about 20 knots, the helicopter slid lightly forward before becoming airborne, then did a 180-degree rotation [to the left] and landed on the taxiway with the main rotor spinning down. The helicopter sustained substantial damage to the last 3 feet of the tail section, with the tail rotor having been severed by the main rotor blades. On February 22, 2012, under the supervision of a Federal Aviation Administration (FAA) aviation safety inspector, the accident flight instructor started the engine with the aid of the fuel boost pump; the engine started immediately. Subsequently, the engine ran smoothly from idle to low power from about 1,300 to 2,000 rpm, with no discrepancies noted. The inspector concluded his inspection by noting that a review of the helicopter’s maintenance records revealed no discrepancies in either the airframe or engine logbooks. The most recent annual inspection was performed on February 10, 2012. The inspector’s examination failed to reveal any anomalies with the engine or airframe that would have precluded normal operation. The reason for the loss of engine power could not be determined. At 1055, the automated weather observing system at GPI, which was located about 7 nautical miles northeast of the S27, reported wind 150 degrees at 9 knots, visibility 10 miles, scattered clouds at 2,400 feet, broken clouds at 2,800 feet, overcast clouds at 5,500 feet, temperature 32 degrees Fahrenheit (F), dew point 27 degrees F, and an altimeter setting of 29.87 inches of mercury. A review of the Carburetor Icing chart revealed that the temperature/dew point spread indicates "Serious icing at glide power” and “Icing at glide and cruise power.” ## Aircraft - Registration: [N51727](https://openairdocs.org/deregistered/N51727-2018-01-09), registration cancelled 2018-01-09, S/N 393, built 1977 (OpenAirDocs) - Reported make and model: ENSTROM F28 (C) - Registry model: [Enstrom F-28C](https://openairdocs.org/model/enstrom-f-28c) (registry code 3300407) (OpenAirDocs) - Registry engine: [Lycoming HIO-360 series](https://openairdocs.org/engine/lycoming-hio-360-series) (registry code 41524, reciprocating) (OpenAirDocs) - Category: Helicopter - Serial number: 393 - Airframe hours: 1483 - Engines: Lycoming HIO-360 215 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, February 10, 2012, 5 hours before - Departed: S27, Kalispell, MT - Destination: S27, Kalispell, MT - Airport: S27, Kalispell City Airport, runway 13, 3,600 × 60 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Flight instructor; age 48; injuries: none; commercial, flight instructor; airplane ratings: multi-engine land, single-engine land; instrument ratings: helicopter, airplane; medical: class 2, without waivers/limitations; last flight review June 28, 2011; seat: right; flight hours: 2,900 total, 272 in this make and model, 2,760 as pilot in command, 140 in the last 90 days, 54 in the last 30 days, 1 in the last 24 hours - Student pilot; age 50; injuries: none; private; airplane ratings: single-engine land; medical: class 2, without waivers/limitations; last flight review June 19, 2010; seat: left; flight hours: 650 total, 55 in this make and model, 590 as pilot in command, 5 in the last 90 days, 5 in the last 30 days, 2 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 150° at 9 knots - Visibility: 10 statute miles - Lowest ceiling: 2,800 ft broken - Temperature: 32 °F, dew point 27 °F - Altimeter: 29.87 inHg - Observed at: GPI, 8 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 20120220001709A](https://openairdocs.org/incident/20120220001709A), Feb 20, 2012: Enstrom F-28C, Kalispell, MT, Substantial damage. On February 20, 2012, about 1030 MST, an Enstrom F-28C helicopter, N51727, was substantially damaged following a loss of power and impact with terrain at the… ## Other investigations on N51727 (2) 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. - [NTSB ANC82DAG01](https://openairdocs.org/ntsb/ANC82DAG01), Oct 1, 1981: Enstrom F-28C (N51727), Big Lake, AK, substantial damage - [NTSB SEA77DYK20](https://openairdocs.org/ntsb/SEA77DYK20), Jul 22, 1977: Enstrom F28C (N51727), Medford, WA, substantial damage ## Docket (5 files) The files NTSB released with the investigation on December 27, 2012, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=82928. 2.7 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 1.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40383615&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Statement from Student Pilot (item 2, .PDF, 519 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40384217&FileExtension=.PDF&FileName=Statement%20from%20Student%20Pilot-Redacted.PDF - Weather Data (item 3, .PDF, 267 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40383616&FileExtension=.PDF&FileName=Weather%20Data-Master.PDF - FAA Inspector's Report (item 4, .PDF, 17 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40383617&FileExtension=.PDF&FileName=FAA%20Inspector%27s%20Report-Redacted.PDF - Retention / Release of Wreckage Form (item 5, .PDF, 65 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40383619&FileExtension=.PDF&FileName=Retention%20%2F%20Release%20of%20Wreckage%20Form-Redacted.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.