Monday, March 14, 2022

Sikorsky S-76D, N761AF: Accidents occurred March 12, 2022 and May 16, 2019

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.

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

Additional Participating Entity:
Federal Aviation Administration / Flight Standards District Office; North Texas

Arkansas Children's Hospital


Location: Texarkana, Arkansas
Accident Number: CEN22LA147
Date and Time: March 12, 2022, 18:45 Local
Registration: N761AF
Aircraft: SIKORSKY AIRCRAFT CORP S-76D 
Injuries: 1 None
Flight Conducted Under: Part 135: Air taxi and commuter - Non-scheduled - Air Medical (Discretionary)

Aircraft and Owner/Operator Information

Aircraft Make: SIKORSKY AIRCRAFT CORP
Registration: N761AF
Model/Series: S-76D Aircraft Category: Helicopter
Amateur Built:
Operator: 
Operating Certificate(s) Held: On-demand air taxi (135)
Operator Designator Code:

Meteorological Information and Flight Plan

Conditions at Accident Site:
Condition of Light:
Observation Facility, Elevation: 
Observation Time:
Distance from Accident Site: 
Temperature/Dew Point:
Lowest Cloud Condition: 
Wind Speed/Gusts, Direction: / ,
Lowest Ceiling: 
Visibility:
Altimeter Setting: 
Type of Flight Plan Filed:
Departure Point: 
Destination:

Wreckage and Impact Information

Crew Injuries: 1 None 
Aircraft Damage: Substantial
Passenger Injuries: N/A
Aircraft Fire: None
Ground Injuries: 
Aircraft Explosion: None
Total Injuries: 1 None
Latitude, Longitude: 33.428844,-94.047933 (est) 







Aviation Accident Final Report - National Transportation Safety Board 

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

Additional Participating Entity:

Federal Aviation Administration / Flight Standards District Office; Little Rock, Arkansas

Investigation Docket - National Transportation Safety Board:

Arkansas Children's Hospital
Location: Morrilton, Arkansas
Accident Number: CEN19LA146
Date and Time: May 15, 2019, 18:33 Local
Registration: N761AF
Aircraft: Sikorsky S76 
Aircraft Damage: Substantial
Defining Event: Powerplant sys/comp malf/fail 
Injuries: 6 None
Flight Conducted Under: Part 135: Air taxi and commuter - Non-scheduled - Air Medical (Unspecified)

Analysis

The pilot of the helicopter air ambulance flight reported that he experienced fumes in the cockpit while enroute, and shortly thereafter, received visual and aural warnings of smoke in the aft baggage compartment. The pilot initiated an emergency descent into an alternate airport, declared an emergency with air traffic control, and landed uneventfully.

Examination of the helicopter revealed that the No. 2 engine exhaust duct was disconnected and unseated, which resulted in engine exhaust entering the compartment containing the tail rotor drive shaft and substantial heat damage to the drive shaft and surrounding areas. Examination of the No. 1 engine exhaust duct revealed that its attach bolts were not tightened to the specified torque value. Additionally, examination of the operator’s other helicopter revealed that the bolts securing both of its two exhaust ducts were not tightened to the specified torque value. The maintenance history of these components was not determined, but given the available information, it is likely that they were improperly secured, which resulted in their loosening and subsequently allowed the exhaust duct to become unseated.

Probable Cause and Findings

The National Transportation Safety Board determines the probable cause(s) of this accident to be:
The improper securing of the exhaust duct bolts, which resulted in the duct becoming unseated and substantial heat damage to the tail rotor drive shaft. 

Findings

Aircraft Fasteners - Incorrect service/maintenance
Aircraft (general) - Incorrect service/maintenance
Personnel issues (general) - Maintenance personnel

Factual Information

On May 15, 2019, about 1833 central daylight time, a Sikorsky S-76D helicopter, N761AF, sustained substantial damage while in cruise flight near Morrilton, Arkansas. The pilot, 2 crewmembers, and 3 passengers were not injured. The helicopter was operated as a Title 14 Code of Federal Regulations Part 135 on-demand air medical flight.

The pilot reported that, 43 minutes into the flight, he experienced fumes in the cockpit. He turned the environmental control system off and immediately descended. Within seconds, he received visual and aural warnings of smoke in the aft baggage compartment. He initiated an emergency descent and declared an emergency with air traffic control and subsequently landed without further incident.

A postaccident examination of the helicopter by a Federal Aviation Administration inspector revealed that the exhaust duct from the No. 2 engine was disconnected and not in its seated position. Exhaust from the No. 2 engine entered the compartment containing the tail rotor drive shaft and resulted in heat damage to drive shaft and surrounding areas. The exhaust ducts are attached using two bolts secured at 110 ft-lbs of pressure. Upon inspection of the No. 1 engine, as well as the operator’s second helicopter, all bolts were found partially disengaged and not tightened to the specified torque value.

History of Flight

Enroute-cruise Powerplant sys/comp malf/fail (Defining event)

Pilot Information

Certificate: Airline transport; Commercial 
Age: 50,Male
Airplane Rating(s): Single-engine land; Multi-engine sea
Seat Occupied: Right
Other Aircraft Rating(s): Helicopter 
Restraint Used: 5-point
Instrument Rating(s): Airplane; Helicopter
Second Pilot Present: No
Instructor Rating(s): None 
Toxicology Performed: No
Medical Certification: Class 1 Without waivers/limitations
Last FAA Medical Exam: April 29, 2019
Occupational Pilot: Yes 
Last Flight Review or Equivalent: March 28, 2019
Flight Time: 6518 hours (Total, all aircraft), 431 hours (Total, this make and model), 5165 hours (Pilot In Command, all aircraft), 32 hours (Last 90 days, all aircraft), 13 hours (Last 30 days, all aircraft), 4 hours (Last 24 hours, all aircraft)

Other flight crew Information

Certificate: None 
Age: Male
Airplane Rating(s): None 
Seat Occupied: Rear
Other Aircraft Rating(s): None 
Restraint Used: 4-point
Instrument Rating(s): None 
Second Pilot Present: No
Instructor Rating(s): None 
Toxicology Performed:
Medical Certification: None 
Last FAA Medical Exam:
Occupational Pilot: No 
Last Flight Review or Equivalent:
Flight Time:

Other flight crew Information

Certificate: None 
Age: Male
Airplane Rating(s): None 
Seat Occupied: Rear
Other Aircraft Rating(s): None 
Restraint Used: 4-point
Instrument Rating(s): None
Second Pilot Present: No
Instructor Rating(s): None 
Toxicology Performed:
Medical Certification: None
Last FAA Medical Exam:
Occupational Pilot: No 
Last Flight Review or Equivalent:
Flight Time:

Passenger Information

Certificate: 
Age:
Airplane Rating(s): 
Seat Occupied: Center
Other Aircraft Rating(s): 
Restraint Used: 4-point
Instrument Rating(s): 
Second Pilot Present: No
Instructor Rating(s): 
Toxicology Performed:
Medical Certification: 
Last FAA Medical Exam:
Occupational Pilot: 
Last Flight Review or Equivalent:
Flight Time:

Passenger Information

Certificate: 
Age: Female
Airplane Rating(s): 
Seat Occupied: Right
Other Aircraft Rating(s):
Restraint Used: 4-point
Instrument Rating(s): 
Second Pilot Present: No
Instructor Rating(s):
Toxicology Performed:
Medical Certification: 
Last FAA Medical Exam:
Occupational Pilot: 
Last Flight Review or Equivalent:
Flight Time:

Passenger Information

Certificate: 
Age: Male
Airplane Rating(s): 
Seat Occupied: Right
Other Aircraft Rating(s):
Restraint Used: 4-point
Instrument Rating(s): 
Second Pilot Present: No
Instructor Rating(s): 
Toxicology Performed:
Medical Certification: 
Last FAA Medical Exam:
Occupational Pilot: 
Last Flight Review or Equivalent:
Flight Time:

Aircraft and Owner/Operator Information

Aircraft Make: Sikorsky 
Registration: N761AF
Model/Series: S76
Aircraft Category: Helicopter
Year of Manufacture: 2013
Amateur Built:
Airworthiness Certificate: Transport 
Serial Number: 761039
Landing Gear Type: Tricycle 
Seats: 6
Date/Type of Last Inspection: March 13, 2019 Continuous airworthiness
Certified Max Gross Wt.: 11875 lbs
Time Since Last Inspection: 205 Hrs
Engines: 2 Turbo shaft
Airframe Total Time: 2488 Hrs as of last inspection 
Engine Manufacturer: Pratt and Whitney
ELT: C126 installed, not activated 
Engine Model/Series: PW210S
Registered Owner: 
Rated Power: 1248 Horsepower
Operator: 
Operating Certificate(s) Held: On-demand air taxi (135)

Meteorological Information and Flight Plan

Conditions at Accident Site: Visual (VMC)
Condition of Light: Day
Observation Facility, Elevation: KRUE, 403 ft msl 
Distance from Accident Site: 25 Nautical Miles
Observation Time: 18:53 Local 
Direction from Accident Site: 285°
Lowest Cloud Condition: Clear 
Visibility 10 miles
Lowest Ceiling: None
Visibility (RVR):
Wind Speed/Gusts: 4 knots / 
Turbulence Type Forecast/Actual:  /
Wind Direction: 300°
Turbulence Severity Forecast/Actual:  /
Altimeter Setting: 29.9 inches Hg 
Temperature/Dew Point: 29°C / 18°C
Precipitation and Obscuration: No Obscuration; No Precipitation
Departure Point: Springdale, AR (14AR)
Type of Flight Plan Filed: Company VFR
Destination: Little Rock, AR (AR62) 
Type of Clearance: VFR flight following
Departure Time: 17:50 Local
Type of Airspace: Class E

Airport Information

Airport: MORRILTON MUNI BDQ 
Runway Surface Type: Asphalt
Airport Elevation: 321 ft msl
Runway Surface Condition: Dry
Runway Used: 09/27 
IFR Approach: None
Runway Length/Width: 4000 ft / 75 ft
VFR Approach/Landing: None

Wreckage and Impact Information

Crew Injuries: 3 None
Aircraft Damage: Substantial
Passenger Injuries: 3 None 
Aircraft Fire: None
Ground Injuries: 
Aircraft Explosion: None
Total Injuries: 6 None 
Latitude, Longitude: 35.1018,-92.7652 (est)