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Location:
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Spearman, Texas
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Accident Number:
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CEN25LA093
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Date & Time:
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February 7, 2025, 16:40 Local
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Registration:
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N7191B
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Aircraft:
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ROBINSON HELICOPTER R22
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Aircraft Damage:
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Substantial
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BETA
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Defining Event:
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Powerplant sys/comp malf/fail
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Injuries:
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1 Minor, 1 None
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Flight Conducted Under:
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Part 91: General aviation - Personal
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Analysis
The pilot reported that, while performing an aerial inspection of a fence, he heard a loud bang come from the engine and the helicopter began to shake and lose altitude. The shaking stopped momentarily but then started again and the engine lost total power. The pilot performed a forced landing, during which the helicopter impacted cedar trees and then rolled several times down a hill. The helicopter sustained substantial damage to the fuselage, tail boom, and main rotor gearbox.
A postaccident inspection of the engine revealed that the No. 3 cylinder intake valve head was burned and chipped specifically on the combustion face, margin, and seat face. Additionally, the bolts that secured the intake manifold system to the engine block were loose.
A review of maintenance records revealed that all four engine cylinders were removed for overhaul and reinstalled about 8 months before the accident due to low compression. According to the pilot, who was also the owner of the helicopter, about one month before the accident (about 360 hours after the cylinders were overhauled), the No. 1 cylinder was replaced due to the intake valve head being burned. According the engine manufacturer, when engine cylinders are removed and/or reinstalled, the bolts that secure the intake manifold system to the engine block need to be removed to manipulate the cylinders. It is likely that when the cylinders were removed 8 months before the accident for overhaul and reinstallation, the bolts that secured the intake manifold system to the engine block were not properly torqued when the cylinders were reinstalled.
The loose intake manifold system likely allowed unmetered air into the engine, resulting in an overly lean fuel/air mixture, which resulted in damage to both the No. 1 and No. 3 cylinder intake valves. The damage to the valves would likely result in poor combustion and a decrease in engine performance.
Probable Cause and Findings
The National Transportation Safety Board determines the probable cause(s) of this accident to be:
Improperly torqued intake manifold bolts that allowed unmetered air to enter the engine, resulting in an overly lean fuel-air mixture, eventual failure of the No. 3 cylinder intake valve, and a total loss of engine power.
Findings
Aircraft Recip eng cyl section - Failure
Aircraft Recip eng cyl section - Incorrect service/maintenance
Personnel issues Repair - Maintenance personnel
Environmental issues Tree(s) - Contributed to outcome
Environmental issues Sloped/uneven terrain - Contributed to outcome
Factual Information
History of Flight
Maneuvering-low-alt flying Powerplant sys/comp malf/fail (Defining event)
On February 7, 2025, about 1640 central standard time, a Robinson R22 helicopter, N7191B, was substantially damaged when it was involved in an accident near Spearman, Texas. The pilot was not injured, and the passenger sustained minor injuries. The helicopter was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.
The pilot reported that they departed near Pampa, Texas, about 1020 for an all-day wildlife management hunting expedition and to inspect fences. While inspecting a fence, the pilot heard a loud bang coming from the engine and the helicopter began to shake. The shaking stopped and then started again, and the engine lost total power. The pilot was unable to find a suitable forced landing site due to uneven terrain, and the helicopter impacted cedar trees and then rolled several times down a hill. The helicopter sustained substantial damage to the fuselage, tail boom, and main rotor gearbox.
A postaccident inspection of the engine revealed that the No. 3 cylinder intake valve head was burned and chipped specifically on the combustion face, margin, and seat face. Additionally, the bolts that secured the intake manifold system to the engine block were loose.
A review of maintenance records revealed that all four engine cylinders were removed for overhaul and reinstalled in June 2024 due to low compression. According to the pilot, who was the owner of the helicopter, in January 2025, about 360 hours after the engine cylinders were overhauled, the No. 1 cylinder was replaced due to the intake valve head being burned. According to the engine manufacturer, when engine cylinders are removed and/or reinstalled, the bolts that secure the intake manifold system to the engine block need to be removed to manipulate the cylinders.
Pilot Information
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Certificate:
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Commercial
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Age:
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62,Male
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Airplane Rating(s):
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Single-engine land
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Seat Occupied:
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Right
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Other Aircraft Rating(s):
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Helicopter
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Restraint Used:
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3-point
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Instrument Rating(s):
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None
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Second Pilot Present:
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No
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Instructor Rating(s):
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None
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Toxicology Performed:
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Medical Certification:
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Class 2 With waivers/limitations
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Last FAA Medical Exam:
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June 18, 2024
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Occupational Pilot:
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Yes
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Last Flight Review or Equivalent:
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January 24, 2024
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Flight Time:
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17136 hours (Total, all aircraft), 15008 hours (Total, this make and model), 17036 hours (Pilot In
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Command, all aircraft), 182 hours (Last 90 days, all aircraft), 43 hours (Last 30 days, all aircraft),
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6 hours (Last 24 hours, all aircraft)
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Aircraft and Owner/Operator Information
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Aircraft Make:
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ROBINSON HELICOPTER
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Registration:
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N7191B
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Model/Series:
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R22 BETA
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Aircraft Category:
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Helicopter
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Year of Manufacture:
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2000
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Amateur Built:
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Airworthiness Certificate:
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Normal
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Serial Number:
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3074
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Landing Gear Type:
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Skid
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Seats:
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2
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Date/Type of Last
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January 23, 2025 100 hour
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Certified Max Gross Wt.:
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1375 lbs
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Inspection:
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Time Since Last Inspection:
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Engines:
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1 Reciprocating
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Airframe Total Time:
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3900 Hrs at time of accident
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Engine Manufacturer:
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Lycoming
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ELT:
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Not installed
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Engine Model/Series:
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O-360
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Registered Owner:
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On file
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Rated Power:
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124 Horsepower
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Operator:
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On file
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Operating Certificate(s)
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None
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Held:
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Meteorological Information and Flight Plan
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Conditions at Accident Site:
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Visual (VMC)
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Condition of Light:
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Day
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Observation Facility, Elevation:
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E42,3055 ft msl
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Distance from Accident Site:
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10 Nautical Miles
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Observation Time:
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16:51 Local
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Direction from Accident Site:
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120°
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Lowest Cloud Condition:
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Clear
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Visibility
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10 miles
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Lowest Ceiling:
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None
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Visibility (RVR):
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Wind Speed/Gusts:
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12 knots / None
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Turbulence Type
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None / None
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Forecast/Actual:
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Wind Direction:
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130°
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Turbulence Severity
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N/A / N/A
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Forecast/Actual:
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Altimeter Setting:
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29.79 inches Hg
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Temperature/Dew Point:
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17°C / 0°C
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Precipitation and Obscuration:
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No Obscuration; No Precipitation
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Departure Point:
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Pampa, TX
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Type of Flight Plan Filed:
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None
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Destination:
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Pampa, TX
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Type of Clearance:
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None
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Departure Time:
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10:20 Local
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Type of Airspace:
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Class G
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Wreckage and Impact Information
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Crew Injuries:
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1 None
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Aircraft Damage:
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Substantial
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Passenger
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1 Minor
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Aircraft Fire:
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None
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Injuries:
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Ground Injuries:
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N/A
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Aircraft Explosion:
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None
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Total Injuries:
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1 Minor, 1 None
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Latitude,
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35.99768,-101.1017(est)
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Longitude:
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Administrative Information
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Investigator In Charge (IIC):
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Abraham, Laura
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Additional Participating
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Robert "Andy" Smith; FAA FSDO
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Persons:
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Original Publish Date:
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January 14, 2026
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Last Revision Date:
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Investigation Class:
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Class 3
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Note:
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The NTSB did not travel to the scene of this accident.
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Investigation Docket:
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https://data.ntsb.gov/Docket?ProjectID=199672
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The National Transportation Safety Board (NTSB) is an independent federal agency charged by Congress with investigating every civil aviation accident in the United States and significant events in other modes of transportation— railroad, transit, highway, marine, pipeline, and commercial space. We determine the probable causes of the accidents and events we investigate, and issue safety recommendations aimed at preventing future occurrences. In addition, we conduct transportation safety research studies and offer information and other assistance to family members and survivors for each accident or event we investigate. We also serve as the appellate authority for enforcement actions involving aviation and mariner certificates issued by the Federal Aviation Administration (FAA) and US Coast Guard, and we adjudicate appeals of civil penalty actions taken by the FAA.
The NTSB does not assign fault or blame for an accident or incident; rather, as specified by NTSB regulation, “accident/incident investigations are fact-finding proceedings with no formal issues and no adverse parties … and are not conducted for the purpose of determining the rights or liabilities of any person” (Title 49 Code of Federal Regulations section 831.4). Assignment of fault or legal liability is not relevant to the NTSB’s statutory mission to improve transportation safety by investigating accidents and incidents and issuing safety recommendations. In addition, statutory language prohibits the admission into evidence or use of any part of an NTSB report related to an accident in a civil action for damages resulting from a matter mentioned in the report (Title 49 United States Code section 1154(b)). A factual report that may be admissible under 49 United States Code section 1154(b) is available here.
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