# NTSB CEN16LA386: Bell 407, N361SF, Lawton, OK, September 29, 2016 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Limited investigation · Final report - Date: September 29, 2016, 06:00 local (11:00 UTC) - Place: Lawton, OK - Coordinates: 34.60889, -98.436668 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=34.6089&lon=-98.4367&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Defining event: [Landing: Loss of control in flight](https://openairdocs.org/ntsb-events/240) - Highest injury: Serious injuries - Injuries: 1 serious, 3 minor - Status: Completed, report March 18, 2019 - Report: Approved by Office Director - NTSB office: Central Region - Parties: Transportation Safety Board of Canada, Federal Aviation Administration - NTSB case key (mKey): 94106 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN16LA386 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/94106/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=94106 - Page: https://openairdocs.org/ntsb/CEN16LA386 ## Probable cause The pilot's loss of helicopter control during landing, which resulted in a hard landing and collision with a wall. ## 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 · Other (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) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Landing: Unknown or undetermined](https://openairdocs.org/ntsb-events/000); cases with it: [Bell 407, 5 cases](https://openairdocs.org/ntsb-events/000/sequence.md?model=1182206), [All aircraft, 1,703 cases](https://openairdocs.org/ntsb-events/000/sequence.md) - [Landing: Loss of control in flight](https://openairdocs.org/ntsb-events/240) (defining event); cases with it: [Bell 407, 10 cases](https://openairdocs.org/ntsb-events/240/sequence.md?model=1182206), [All aircraft, 5,002 cases](https://openairdocs.org/ntsb-events/240/sequence.md) ## Analysis The commercial pilot of the helicopter was approaching to land on a helipad. It was his first landing to this helipad, though he had departed from the helipad the day before. Due to trees and transmission lines near the helipad, the pilot flew a slight right-turning, steep approach. When the helicopter was about 125 ft above the pad and 150 ft to the southwest of it, the pilot commanded left cyclic to stop the right turn. He estimated the helicopter to be 40 knots above effective transitional lift, and in a stable 500 ft per minute descent; there was a headwind. The helicopter did not respond to his control input, and the pilot announced to the crew his intention to go around. He increased left cyclic until the cyclic was against his left leg and the helicopter still did not respond. The pilot lost control of the helicopter and it landed hard, colliding with a wall. Data extracted from the engine control unit (ECU) was consistent with the engine producing the required power and responding to collective control inputs; however, the data indicated that the main rotor speed and torque were exceeded. These exceedances suggested that a large demand for power was commanded by the pilot, likely during the go-around. Examination of the helicopter did not reveal any mechanical anomalies that would have precluded normal operation. The helicopter was in a right bank with 3 crewmembers seated on the right side of the helicopter, one crewmember seated on the left side, and was carrying a near-full fuel load. The distribution of crew members and a high torque setting may have contributed to the pilot's inability to maintain helicopter control; however, the extent to which these factors may have contributed could not be determined. ## Factual narrative On September 29, 2016, about 0600 central daylight time, N361SF, a Bell 407 helicopter, impacted terrain following a loss of control while attempting to land at the Comanche County Memorial Hospital Heliport (18OK), Lawton, Oklahoma. The pilot and 2 crew members had minor injuries. One crew member was seriously injured, and the helicopter was substantially damaged. The helicopter was owned and operated by Survival Flight under the provisions of 14 Code of Federal Regulations Part 135 as a positioning flight. Night visual meteorological conditions prevailed for the flight which operated on a company flight plan.The pilot reported that he approached the helipad from the southwest. It was his first landing to this helipad but had departed from the helipad on the day prior. Due to trees and transmission lines within 40-50 ft of the elevated helipad, the pilot flew a slight right-turning, steep approach. When the helicopter was approximately 125 ft above the pad and 150 ft to the southwest, the pilot commanded left cyclic to stop the right turn. He estimated the helicopter was below 40 knots, but above effective transitional life, with wind off the nose of the helicopter or slightly left, and a stable 500-ft per minute descent. The helicopter did not respond to his control input and the pilot announced his intension to the crew to go-around. He increased left cyclic until it was against his left leg and the helicopter still did not respond. The pilot lost control of the helicopter and it landed hard colliding with a wall. An inspector from the Federal Aviation Administration (FAA) examined the airframe with the assistance of a technical representative from Bell Helicopter. No preimpact anomalies were discovered with the wreckage. The engine control unit (ECU) was removed from the helicopter and sent to Triumph in West Hartford, Connecticut. With oversight from an FAA inspector, data from the unit was downloaded. The data extracted was consistent with the engine producing the required power and responding to collective control inputs. Exceedance information captured by the ECU recorded an exceedance of main rotor speed (Nr) and torque (Q). The unit recorded 10 lines of data with this exceedance which contained information consistent with the accident sequence. Prior to the accident there were 2 spikes in engine parameters. Without changes in collective inputs, demands of flight control inputs could impact a spike on engine demand. On the NTSB Form 6120, the pilot stated that the helicopter was loaded with 3 crew members on the right side of the helicopter, and a near full fuel load. Up to the accident landing, the helicopter had flown for 6 hours including 6 approaches and night landings at other hospitals without incident. ## Aircraft - Registration: [N361SF](https://openairdocs.org/deregistered/N361SF-2019-10-04), registration cancelled 2019-10-04, S/N 53490, built 2001 (OpenAirDocs) - Reported make and model: BELL 407 - Registry model: [Bell 407](https://openairdocs.org/model/bell-407) (registry code 1182206) (OpenAirDocs) - Registry engine: [Allison 250-C47 series](https://openairdocs.org/engine/allison-250-c47-series) (registry code 03029, turbo-shaft) (OpenAirDocs) - Category: Helicopter - Serial number: 53490 - Year built: 2001 - Airframe hours: 2261.2 - Engines: Allison 250-C47B 813 horsepower turbo shaft - Damage: Substantial damage - Flight: Part 135 - Operator: Viking Aviation LLC, doing business as Survival Flight Services LLC - Registered owner: Air ER LLC - Airworthiness certificate: Standard, Normal - Last inspection: AAIP, September 24, 2016 - Departed: LAW, LAWTON, OK - Destination: Lawton, OK - Flight plan: Company VFR - Equipment: Satellite tracking device, Auto-pilot ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 46; injuries: minor; commercial; airplane ratings: single-engine land; instrument ratings: airplane, helicopter; medical: class 2, without waivers/limitations; last flight review January 13, 2016; seat: front; restraint: 3-point; flight hours: 2,838 total, 140 in this make and model, 2,191 as pilot in command, 37 in the last 90 days, 21 in the last 30 days, 3 in the last 24 hours ## Weather - Conditions: Visual (VMC), Night - Wind: 360° at 8 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 54 °F, dew point 48 °F - Altimeter: 30.28 inHg - Observed at: KFSI, 3 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 20160929016039A](https://openairdocs.org/incident/20160929016039A), Sep 29, 2016: Bell 407, Lawton, OK, Substantial damage. Emergency services (EMS) rotorcraft N361SF, Bell 407, was on the approach segment inbound to comanche county community Hospital?s rooftop heliport (180K) and… ## Docket (5 files) The files NTSB released with the investigation on April 12, 2018, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=94106. 4.6 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 3.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40461935&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Site Diagram (item 2, .PDF, 215 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40461936&FileExtension=.PDF&FileName=Site%20Diagram-Master.PDF - Download Graphics (item 3, .PDF, 903 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40461937&FileExtension=.PDF&FileName=Download%20Graphics-Master.PDF - Record of Conversation (Rolls-Royce) (item 4, .PDF, 318 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40461938&FileExtension=.PDF&FileName=Record%20of%20Conversation%20(Rolls-Royce)-Master.PDF - FAA Observation of Download (item 5, .PDF, 15 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40461939&FileExtension=.PDF&FileName=FAA%20Observation%20of%20Download-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.