# NTSB CEN17LA188: Bell 407, N6040Y, Fort Worth, TX, January 24, 2017 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: January 24, 2017, 08:45 local (14:45 UTC) - Place: Fort Worth, TX - Coordinates: 33.049167, -97.293609 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=33.0492&lon=-97.2936&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Defining event: [Landing: Hard landing](https://openairdocs.org/ntsb-events/092) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report September 6, 2017 - Report: Approved by Office Director - NTSB office: Central Region - Parties: FAA Flight Standards, Bell Helicopter Textron - NTSB case key (mKey): 95195 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN17LA188 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/95195/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=95195 - Page: https://openairdocs.org/ntsb/CEN17LA188 ## Probable cause The flight instructor's failure to prevent the engine/rotor overspeed condition during the demonstration maneuver and the excessive descent rate during the emergency landing, which resulted in a hard landing. Contributing to the engine/rotor overspeed condition was the flight instructor's failure to comply with the demonstration procedure. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Use of equip/info: aircraft control](https://openairdocs.org/ntsb-findings/02063040): Personnel issues › Task performance · Instructor/check pilot (probable cause); cases with it: [Bell 407, 19 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md?model=1182206), [All aircraft, 9,295 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md) - [Performance/control parameters: descent rate](https://openairdocs.org/ntsb-findings/01062037): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Bell 407, 2 cases](https://openairdocs.org/ntsb-findings/01062037/cases.md?model=1182206), [All aircraft, 242 cases](https://openairdocs.org/ntsb-findings/01062037/cases.md) - [Use of equip/info: use of equip/system](https://openairdocs.org/ntsb-findings/02063015): Personnel issues › Task performance · Pilot (probable cause); cases with it: [Bell 407, 6 cases](https://openairdocs.org/ntsb-findings/02063015/cases.md?model=1182206), [All aircraft, 1,391 cases](https://openairdocs.org/ntsb-findings/02063015/cases.md) - [Use of equip/info: use of policy/procedure](https://openairdocs.org/ntsb-findings/02063032): Personnel issues › Task performance · Instructor/check pilot (probable cause); cases with it: [Bell 407, 3 cases](https://openairdocs.org/ntsb-findings/02063032/cases.md?model=1182206), [All aircraft, 191 cases](https://openairdocs.org/ntsb-findings/02063032/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Maneuvering-hover: Simulated/training event](https://openairdocs.org/ntsb-events/600); cases with it: [Bell 407, 2 cases](https://openairdocs.org/ntsb-events/600/sequence.md?model=1182206), [All aircraft, 173 cases](https://openairdocs.org/ntsb-events/600/sequence.md) - [Emergency descent: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Bell 407, 8 cases](https://openairdocs.org/ntsb-events/440/sequence.md?model=1182206), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) - [Landing: Hard landing](https://openairdocs.org/ntsb-events/092) (defining event); cases with it: [Bell 407, 13 cases](https://openairdocs.org/ntsb-events/092/sequence.md?model=1182206), [All aircraft, 2,102 cases](https://openairdocs.org/ntsb-events/092/sequence.md) ## Analysis The flight instructor was demonstrating the emergency procedure for a full-authority digital engine control (FADEC) failure that would cause it to switch from auto to manual mode as part of the helicopter manufacturer's training program. The instructor stated that the helicopter was in a stable 5-ft hover when he was demonstrating the maneuver. To begin the demonstration, the flight instructor intentionally switched the FADEC to the manual mode. After about 10 seconds, the engine speed began to increase, which resulted in a corresponding increase in the main rotor speed. The instructor increased the collective control input in an attempt to control the engine and rotor speeds. The helicopter subsequently climbed and began to shake violently. The instructor initiated a descent for landing with an excessive descent rate, which resulted in damage to the landing skids and tailboom upon touchdown. The helicopter flight manual emergency procedure for a FADEC failure and the training program procedure for the FADEC manual mode demonstration both noted that the engine and rotor speeds must be maintained between 95% and 100% with the collective and throttle controls. The demonstration procedure also noted that the throttle control should be in the fly position when the FADEC is placed into manual mode. A review of engine data recovered from the FADEC indicated that the throttle was not in the fly position before beginning the demonstration, which likely resulted in a greater increase in engine and rotor speeds than would have been expected. The flight instructor did not promptly manage the increase in the engine and rotor speeds, which resulted in an inadvertent overspeed condition and subsequent airframe vibrations that prompted the need for an emergency landing. ## Factual narrative On January 24, 2017, about 0845 central standard time, a Bell 407 helicopter, N6040Y, was substantially damaged during a hard landing at the Bell Training Facility Heliport (3XS7), Fort Worth, Texas. The flight instructor and pilot receiving instruction were not injured. The helicopter was registered to and operated by Bell Helicopter Textron as a 14 Code of Federal Regulations Part 91 instructional flight. Visual meteorological conditions prevailed at the time of the accident. The flight was not operated on a flight plan. The flight originated from the Bell Helicopter Hurst Heliport about 0820.The flight instructor stated that he was demonstrating the emergency procedure for a failure of the full authority digital engine control (FADEC) unit from auto to manual mode. The helicopter was in a stable 5-foot hover at the time. To begin the demonstration, the FADEC was intentionally switched into manual mode. After approximately 10 seconds, the engine speed began to increase, which resulted in a corresponding increase in the main rotor speed. The instructor increased the collective control input in an attempt to control the engine and rotor speeds. The helicopter subsequently climbed to about 25 feet above ground level (agl) and began to shake violently. The instructor initiated a descent for landing; however, the helicopter contacted the ground with a sufficient descent rate to "spread the skids." The helicopter was shut down and the pilots exited without injuries. Maintenance personnel noticed a crease in the tailboom after it was repainted as part of the repair process. The helicopter maintenance manual stated that creases in tailboom skins are not permitted under any circumstances. In such instances, the tailboom must be repaired or replaced. Data recovered from the FADEC unit revealed that, at the time the FADEC was switched from auto to manual mode, the throttle position (PLA) was 98%, the rotor speed was 100%, and the fuel flow 264 pounds per hour. About 3 seconds later, the rotor speed, engine speed, and fuel flow began to increase. The rotor speed reached a maximum of 118%. The throttle position was subsequently reduced with a corresponding decrease in engine and rotor speeds. The helicopter flight manual stated that in the case of a FADEC failure, the pilot must maintain the engine and rotor speeds between 95% and 100% with the collective and throttle controls, and land as soon as practical. The procedure included a warning that depending on the flight profile and power setting at the time of the failure, the transition to manual mode may result in an increase (overspeed) or a decrease (underspeed) of the engine/rotor speed within 2 to 7 seconds after the failure warning, requiring positive movements of the collective and throttle. The procedure for the FADEC manual mode demonstration noted that the throttle control should be in the fly position when the FADEC is placed into manual mode. The engine and rotor speeds should be maintainedbetween 95% and 100% during the maneuver. According to the helicopter manufacturer, the throttle fly position corresponded to a PLA of 90% in the FADEC data. As a result, a PLA of 98% was consistent with the throttle not being in the fly position at the time of the FADEC demonstration. Without the throttle in the fly position, when the FADEC is switched into manual mode, the unit will adjust fuel flow to that commanded by the throttle setting. In the accident scenario, this was an increase in fuel flow from that being provided by the FADEC in auto mode to maintain the hover, which caused the engine and rotor speeds to increase. As a result of the accident, the helicopter manufacturer revised the training program to perform the FADEC manual mode training in a flight simulator/training device rather than in the helicopter. ## Aircraft - Registration: [N6040Y](https://openairdocs.org/aircraft/N6040Y), registered now, S/N 53371, built 1999 (OpenAirDocs) - Reported make and model: BELL 407 - Registry model: [Bell 407](https://openairdocs.org/model/bell-407) (registry code 1182206) (OpenAirDocs) - Registry engine: [Rolls-Royce 250-C47B](https://openairdocs.org/engine/rolls-royce-250-c47b) (registry code 54585, turbo-shaft) (OpenAirDocs) - Category: Helicopter - Serial number: 53371 - Year built: 1999 - Airframe hours: 8530 - Engines: Rolls-Royce 250-C47B 650 horsepower turbo shaft - Damage: Substantial damage - Flight: Instructional, Part 91 - Operator: Bell Helicopter Textron Inc. - Registered owner: Bell Helicopter Textron Inc. - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, November 29, 2016, 8 hours before - Departed: 0TE2, Hurst, TX - Destination: 3XS7, Fort Worth, TX - Airport: 3XS7, Bell Training Facility ## Flight crew As NTSB recorded them. NTSB leaves out names. - Flight instructor; age 36; injuries: none; airline transport, flight instructor; airplane ratings: single-engine land; instrument ratings: helicopter, airplane; medical: class 2, without waivers/limitations; last flight review December 19, 2016; seat: left; restraint: 4-point; flight hours: 3,030 total, 18 in this make and model, 2,429 as pilot in command, 18 in the last 90 days, 18 in the last 30 days, 2 in the last 24 hours - Pilot; age 68; injuries: none; commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane, helicopter; medical: class 2, with waivers/limitations; seat: right; restraint: 4-point ## Weather - Conditions: Visual (VMC), Day - Wind: 180° at 10 knots - Visibility: 10 statute miles - Lowest ceiling: 25,000 ft broken - Temperature: 55 °F, dew point 37 °F - Altimeter: 29.64 inHg - Observed at: AFW, 13 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 20170124007419A](https://openairdocs.org/incident/20170124007419A), Jan 24, 2017: Bell 407, Fort Worth Tx, TX, Substantial damage. During simulated fadec failure the engine and rotor entered into an overspeed condition. PIC pulled up on the collective to try to slow the rotor system… ## Other investigations on N6040Y (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 CEN09CA604](https://openairdocs.org/ntsb/CEN09CA604), Sep 23, 2009: Bell 407 (N6040Y), Fort Worth, TX, substantial damage. Probable cause: Failure of the pilot to maintain control during landing. ## Docket (8 files) The files NTSB released with the investigation on June 15, 2017, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=95195. 4.1 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 1.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40453242&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Instructor Statement (item 2, .PDF, 257 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40453243&FileExtension=.PDF&FileName=Instructor%20Statement-Master.PDF - Pilot Statement (item 3, .PDF, 284 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40453244&FileExtension=.PDF&FileName=Pilot%20Statement-Master.PDF - Conversation Summary -- Helicopter Manufacturer Representatives (item 4, .PDF, 125 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40453245&FileExtension=.PDF&FileName=Conversation%20Summary%20--%20Helicopter%20Manufacturer%20Representatives-Master.PDF - Plot of FADEC Data (item 5, .PDF, 95 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40453246&FileExtension=.PDF&FileName=Plot%20of%20FADEC%20Data-Master.PDF - Flight Manual Excerpt -- FADEC Failure Emerg Procedure (item 6, .PDF, 345 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40453247&FileExtension=.PDF&FileName=Flight%20Manual%20Excerpt%20--%20FADEC%20Failure%20Emerg%20Procedure-Master.PDF - Revised Pilot Training Syllabus -- Excerpt (item 7, .PDF, 1.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40453248&FileExtension=.PDF&FileName=Revised%20Pilot%20Training%20Syllabus%20--%20Excerpt-Master.PDF - Weather Documentation -- Ft Worth Alliance Airport (item 8, .PDF, 43 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40453249&FileExtension=.PDF&FileName=Weather%20Documentation%20--%20Ft%20Worth%20Alliance%20Airport-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.