Sunday, April 15, 2018

Bell 407, N361SF, owned and operated by Survival Flight: Accident occurred September 29, 2016 at Comanche County Memorial Hospital Heliport (18OK), Lawton, Oklahoma

The National Transportation Safety Board did not travel to the scene of this accident.

Additional Participating Entities:
Federal Aviation Administration / Flight Standards District Office; Oklahoma City, Oklahoma
Transportation Safety Board of Canada; Gatineau, Quebec

Aviation Accident Factual Report - National Transportation Safety Board: https://app.ntsb.gov/pdf

Investigation Docket - National Transportation Safety Board: https://dms.ntsb.gov/pubdms

http://registry.faa.gov/N361SF



Aviation Accident Factual Report - National Transportation Safety Board

Location: Lawton, OK
Accident Number: CEN16LA386
Date & Time: 09/29/2016, 0600 CDT
Registration: N361SF
Aircraft: BELL 407
Aircraft Damage: Substantial
Defining Event: Loss of control in flight
Injuries: 1 Serious, 3 Minor
Flight Conducted Under: Part 135: Air Taxi & Commuter - Non-scheduled - Air Medical (Discretionary) 

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. 

Pilot Information

Certificate: Commercial
Age: 46, Male
Airplane Rating(s): Single-engine Land
Seat Occupied: Front
Other Aircraft Rating(s): Helicopter
Restraint Used: 3-point
Instrument Rating(s): Airplane; Helicopter
Second Pilot Present: No
Instructor Rating(s): Helicopter; Instrument Helicopter
Toxicology Performed: No
Medical Certification: Class 2 Without Waivers/Limitations
Last FAA Medical Exam: 05/25/2016
Occupational Pilot: Yes
Last Flight Review or Equivalent: 01/13/2016
Flight Time:  2838 hours (Total, all aircraft), 140 hours (Total, this make and model), 2191 hours (Pilot In Command, all aircraft), 37 hours (Last 90 days, all aircraft), 21 hours (Last 30 days, all aircraft), 3 hours (Last 24 hours, all aircraft) 



Aircraft and Owner/Operator Information

Aircraft Manufacturer: BELL
Registration: N361SF
Model/Series: 407
Aircraft Category: Helicopter
Year of Manufacture: 2001
Amateur Built: No
Airworthiness Certificate: Normal
Serial Number: 53490
Landing Gear Type: High Skid
Seats: 5
Date/Type of Last Inspection: 09/24/2016, AAIP
Certified Max Gross Wt.: 5280 lbs
Time Since Last Inspection:
Engines: 1 Turbo Shaft
Airframe Total Time: 2261.2 Hours at time of accident
Engine Manufacturer: Allison
ELT: C126 installed, not activated
Engine Model/Series: 250-C47B
Registered Owner: Air ER LLC
Rated Power: 813 hp
Operator: Viking Aviation LLC
Operating Certificate(s) Held: On-demand Air Taxi (135)
Operator Does Business As:  Survival Flight Services LLC
Operator Designator Code: 7ALA 

Meteorological Information and Flight Plan

Conditions at Accident Site: Visual Conditions
Condition of Light: Night
Observation Facility, Elevation: KFSI, 1188 ft msl
Observation Time: 0558 CDT
Distance from Accident Site: 3 Nautical Miles
Direction from Accident Site: 36°
Lowest Cloud Condition: Clear
Temperature/Dew Point: 12°C / 9°C
Lowest Ceiling: None
Visibility: 10 Miles
Wind Speed/Gusts, Direction: 8 knots, 360°
Visibility (RVR):
Altimeter Setting: 30.28 inches Hg
Visibility (RVV):
Precipitation and Obscuration: No Obscuration; No Precipitation
Departure Point: LAWTON, OK (LAW)
Type of Flight Plan Filed: Company VFR
Destination: Lawton, OK
Type of Clearance: VFR
Departure Time: 0600 CDT
Type of Airspace: Class E

Wreckage and Impact Information

Crew Injuries: 1 Serious, 3 Minor
Aircraft Damage: Substantial
Passenger Injuries: N/A
Aircraft Fire: None
Ground Injuries: N/A
Aircraft Explosion: None
Total Injuries: 1 Serious, 3 Minor
Latitude, Longitude: 34.608889, -98.436667 (est)

NTSB Identification: CEN16LA386
14 CFR Part 91: General Aviation
Accident occurred Thursday, September 29, 2016 in Lawton, OK
Aircraft: BELL 407, registration: N361SF
Injuries: 4 Minor.

This is preliminary information, subject to change, and may contain errors. Any errors in this report will be corrected when the final report has been completed. NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

On September 29, 2016, about 0600 central daylight time, a Bell 407 helicopter, N361SF, impacted terrain following a loss of control while attempting to land at the Comanche Country Memorial Hospital Heliport (18OK), Lawton, Oklahoma. The pilot and 3 crew members sustained minor injuries and the helicopter was substantially damaged. The helicopter was registered to and operated by Survival Flight Inc. under the provisions of 14 Code of Federal Regulations Part 91 as a positioning flight. Visual meteorological conditions prevailed for the flight which operated on a company flight plan.

The pilot reported that he maneuvered the helicopter to align with the helipad. During the descending right turn to the helipad, the pilot input left cyclic and the helicopter was unresponsive. The pilot lost control of the helicopter and it landed hard then collided with a wall.  The helicopter was retained for further examination.

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