# NTSB ERA13LA344: Hughes 369D, N31HM, Center Point, WV, July 29, 2013 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: July 29, 2013, 11:40 local (15:40 UTC) - Place: Center Point, WV - Coordinates: 39.451667, -80.569168 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=39.4517&lon=-80.5692&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Defining event: [Maneuvering-hover: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed, report August 7, 2014 - Report: Approved by Office Director - NTSB office: Eastern Region Aviation - Parties: Rolls-Royce, FAA/FSDO - NTSB case key (mKey): 87623 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ERA13LA344 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/87623/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=87623 - Page: https://openairdocs.org/ntsb/ERA13LA344 ## Probable cause A total loss of engine power for reasons that could not be determined because postaccident examination of the airframe and engine 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: [Hughes Helicopters HUGHES 369D, 8 cases](https://openairdocs.org/ntsb-findings/05000000/cases.md?model=4470706), [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. - [Maneuvering-hover: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) (defining event); cases with it: [Hughes Helicopters HUGHES 369D, 12 cases](https://openairdocs.org/ntsb-events/341/sequence.md?model=4470706), [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: [Hughes Helicopters HUGHES 369D, 9 cases](https://openairdocs.org/ntsb-events/440/sequence.md?model=4470706), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) - [Emergency descent: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Hughes Helicopters HUGHES 369D, 26 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=4470706), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) - [Uncontrolled descent: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Hughes Helicopters HUGHES 369D, 26 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=4470706), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis The pilot reported that, after trimming the top portion of a tree during helicopter tree-trimming operations, the engine experienced a gradual loss of power. The rotor rpm then began to decrease, and the "engine out" alarm illuminated and sounded. The pilot maneuvered to avoid power lines; however, during the descent, the rotor blades struck a power line pole, and the helicopter impacted the ground, which resulted in substantial damage to all five main rotor blades and the left landing skid. Postaccident examination of the engine and airframe and the air, fuel, and oil systems revealed no anomalies that could have contributed to the loss of power. ## Factual narrative On July 29, 2013, about 1140 eastern daylight time, a McDonnell Douglas 369D helicopter, N31HM, impacted a power pole during descent following a total loss of engine power during tree trimming operations near Center Point, West Virginia. The commercial pilot sustained minor injuries and the helicopter received substantial damage. The helicopter was owned and operated DAH Aircraft, LLC, under 14 Code of Federal Regulations Part 133, as an external load flight. Visual meteorological conditions prevailed and no flight plan was filed for the flight. The flight originated from a remote landing zone (LZ) about 1.5 nautical miles to the northwest and was destined back to the same LZ.According to the pilot, after trimming the top portion of a tree that was overhanging a power line, he noticed a gradual loss of power with no noticeable yaw. The rotor rpm began to decrease, causing the "Engine Out" alarm to illuminate and sound. The pilot lowered the collective to preserve rotor RPM, and nosed forward and to the right to avoid landing directly onto the power line. During the descent, the rotor blades struck the power line pole. The helicopter impacted the ground on its right side in a dense wooded area. Initial examination of the helicopter by a Federal Aviation Administration (FAA) inspector revealed that the helicopter sustained substantial damage to all five main rotor blades and to the left landing skid. Further examination of the helicopter revealed substantial damage to the right side of the cabin section frame, landing skids, main rotor system, and to the tail boom. According to the helicopter engine logbooks, the engine had a recorded total time of 19,082.8 flight hours with a recorded 29 hours since last annual inspection, and a recorded 4,266.4 hours since overhaul. The helicopter was powered by a Rolls-Royce 250-C20B turbo-shaft engine, serial number CAE-821945F. Review of the helicopter's airframe logbooks revealed that its most recent annual inspection was complete on September 27, 2013, at a total airframe time of 10,446 hours. A fuel vacuum check was completed on the engine and airframe fuel supply system with no discrepancies. A check of engine air, fuel and oil systems was found to have no anomalies. Flight control continuity from the flight controls to all surfaces was completed with no discrepancies noted. The engine was removed and sent to the manufacturer for further testing. The engine was placed in a test cell and run through several power settings with no anomalies noted. A detailed report from the engine manufacturer is contained in the NTSB public docket. A review of the helicopter weight and balance revealed that the pilot was operating the helicopter within the manufacturer's designated weight limits. A review of the 1153 recorded data from North Central West Virginia Airport; Clarksburg, West Virginia (KCKB), revealed winds variable at 5 knots, visibility 10 statute miles, few clouds at 3,900 feet above ground level,temperature 21 degrees Celsius, dew point 12 degrees Celsius, and an altimeter of 30.15 inches of mercury. ## Aircraft - Registration: [N31HM](https://openairdocs.org/aircraft/N31HM), registered now, S/N 1160027D, built 1977 (OpenAirDocs) - Reported make and model: HUGHES 369D - Registry model: [Hughes Helicopters HUGHES 369D](https://openairdocs.org/model/hughes-helicopters-hughes-369d) (registry code 4470706) (OpenAirDocs) - Registry engine: [Allison 250-C20 series](https://openairdocs.org/engine/allison-250-c20-series) (registry code 03020, turbo-prop) (OpenAirDocs) - Category: Helicopter - Serial number: 1160027D - Year built: 1977 - Airframe hours: 10446 - Engines: Rolls Royce 250C20B 420 horsepower turbo shaft - Damage: Substantial damage - Flight: External load, Part 133 - Operator: Dah Aircraft LLC - Registered owner: Dah Aircraft LLC - Airworthiness certificate: Special, Restricted (Special); Standard, Normal - Last inspection: 100 hour, July 24, 2013, 29 hours before - Departed: Center Point, WV - Destination: Center Point, WV ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 32; injuries: minor; commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 2; last flight review January 3, 2013; seat: left; restraint: 4-point; flight hours: 789 total, 515 in this make and model, 626 as pilot in command, 336 in the last 90 days, 104 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: variable at 5 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 70 °F, dew point 54 °F - Altimeter: 30.14 inHg - Observed at: KCKB, 32 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 20130729015279A](https://openairdocs.org/incident/20130729015279A), Jul 29, 2013: Hughes 369D, Folsom, WV, Substantial damage. Folsom, WV: N31HM, a H369D, while performing power line right-of-way tree triming, experienced a sudden engine power loss. The rotorcraft settled into heavy… ## Other investigations on N31HM (1) 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 LAX07LA270](https://openairdocs.org/ntsb/LAX07LA270), Sep 8, 2007: Hughes 369D (N31HM), Ellensburg, WA, no damage, 1 fatal. Probable cause: The passenger's inadequate visual lookout and failure to maintain clearance from the rotating main rotor disc while the helicopter was hovering. An uphill terrain condition was a factor ## Docket (10 files) The files NTSB released with the investigation on May 7, 2014, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=87623. 8.3 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 1.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40412014&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Helicopter Weight & Balance Sheet (item 2, XLSX, 14 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40412015&FileExtension=xlsx&FileName=Helicopter%20Weight%20%26%20Balance%20Sheet-Master - Mr. McGuire Statement (item 3, .PDF, 98 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40412016&FileExtension=.PDF&FileName=Mr.%20McGuire%20Statement-Master.PDF - FAA Notes (item 4, .PDF, 29 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40412017&FileExtension=.PDF&FileName=FAA%20Notes-Redacted.PDF - Reports from Parties to the Investigation (Engine Run) (item 5, .PDF, 3.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40412018&FileExtension=.PDF&FileName=Reports%20from%20Parties%20to%20the%20Investigation%20(Engine%20Run)-Redacted.PDF - Weather Reports and Records (item 6, .PDF, 108 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40412019&FileExtension=.PDF&FileName=Weather%20Reports%20and%20Records-Master.PDF - Excerpts from Maintenance Logs (item 7, .PDF, 955 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40412020&FileExtension=.PDF&FileName=Excerpts%20from%20Maintenance%20Logs-Redacted.PDF - Statement of Party Representatives to NTSB Investigation (item 8, .PDF, 893 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40412021&FileExtension=.PDF&FileName=Statement%20of%20Party%20Representatives%20to%20NTSB%20Investigation-Redacted.PDF - Photo 1_Helicopter at Rest (Courtesy of the FAA) (item 9, .PDF, 373 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40412023&FileExtension=.PDF&FileName=Photo%201_Helicopter%20at%20Rest%20(Courtesy%20of%20the%20FAA)-Master.PDF - Photo 2_Damage to the Right Side (Courtesy of the FAA) (item 10, .PDF, 664 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40412024&FileExtension=.PDF&FileName=Photo%202_Damage%20to%20the%20Right%20Side%20(Courtesy%20of%20the%20FAA)-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.