The National Transportation Safety Board did not travel to the scene of this accident.
Additional Participating Entities:
Federal Aviation Administration / Flight Standards District Office; Irving, Texas
Additional Participating Entities:
Federal Aviation Administration / Flight Standards District Office; Irving, Texas
Textron Aviation; Wichita, Kansas
Investigation Docket - National Transportation Safety Board:
Location: Greenville, Texas
Accident Number: CEN19LA166
Date & Time: June 12, 2019, 17:25 Local
Registration: N176TW
Aircraft: Beech E90
Aircraft Damage: Substantial
Defining Event: Part(s) separation from AC
Injuries: 3 None
Flight Conducted Under: Part 91: General aviation - Instructional
Analysis
The pilots were performing an instructional flight with multiple takeoffs and landings when, during one takeoff, the pilots heard a loud noise, and the right main landing gear (MLG) wheel assembly departed the airplane. The pilots elected to perform an emergency landing at another airport due to its larger runways and emergency personnel and equipment. The airplane landed and came to rest upright on the runway surface. Examination of the airplane after landing revealed that the right main wheel/tire and lower shock absorber assembly departed the upper shock absorber assembly. The separated assembly, which was located near the departure airport, impacted the right horizontal stabilizer after separation, which sustained substantial damage.
Metallurgical examination of the assembly revealed that the MLG fractured at the connection between the upper and lower torque knees. Fatigue was identified on a fractured piece of the upper torque knee, and other fractures on the torque knee were consistent with overload. Corrosion assisted in crack initiation, and the crack propagated through fatigue until a critical crack length was reached. It is likely that the fatigue area fractured first and the other connections experienced an increase in loading, which caused them to separate from the MLG assembly.
Probable Cause and Findings
The National Transportation Safety Board determines the probable cause(s) of this accident to be:
The fatigue failure of the right main landing gear upper torque knee.
Findings
Aircraft Main gear strut/axle/truck - Fatigue/wear/corrosion
Aircraft Main gear strut/axle/truck - Failure
Factual Information
On June 12, 2019, about 1725 central daylight time, a Beech E90 airplane, N176TW, experienced a right main landing gear (MLG) failure during takeoff from Majors Airport (GVT), Greenville, Texas, and an emergency landing was performed at Fort Worth Alliance Airport (AFW), Fort Worth, Texas. The two airline transport pilots and a company check pilot were not injured, and the airplane sustained
substantial damage to the right horizontal stabilizer. The airplane was registered to Sierra American Corporation, Wilmington, Delaware, and operated by Ameristar Jet Charter, Inc., Addison, Texas, as a Title 14 Code of Federal Regulations Part 91 instructional flight. Day visual meteorological conditions prevailed at the time of the accident, and a visual flight rules flight plan was filed. The flight was originating from GVT.
According to the operator, the pilots were performing an instructional flight with multiple takeoffs and landings at GVT. During the accident takeoff, the pilots heard a loud noise, and with the assistance of ground witnesses, determined the right MLG wheel assembly departed the airplane. The separated wheel assembly and fractured components were located near the runway at GVT. The pilots elected to perform an emergency landing at AFW due to large runways and emergency personnel and equipment. The airplane landed and came to rest upright on the runway surface.
Examination of the airplane revealed the right main wheel/tire and lower shock absorber assembly departed the upper shock absorber assembly. The separated assembly then impacted the right horizontal stabilizer, and the stabilizer sustained substantial damage. The lower shock absorber assembly was recovered at GVT and retained for further materials examination.
On June 27, 2019, at Textron Aviation, Wichita, Kansas, the right MLG assembly was examined by Textron Aviation engineers under the supervision of a Federal Aviation Administration (FAA) engineer. According to the Textron engineering report, the MLG was found to have fractured at the connection between the upper and lower torque knees (part numbers 50-810032-4, 50-810295-17), and at two other connection points in the upper torque knee. The examination resulted in the following findings:
1. The upper torque knee was found to have fractured at all three connection points.
2. Fatigue was identified on a fractured piece of the upper torque knee, and all other fractures were consistent with overload.
3. Corrosion was found to have assisted in crack initiation. The crack propagated through fatigue until a critical crack length was reached.
4. Material chemistry, tensile properties, conductivity, and microstructure of the upper torque link was consistent with aluminum alloy 2014 in the T6 condition.
The Textron engineering report was reviewed and approved by the National Transportation Safety Board materials laboratory chief engineer.
According to Textron, due to historical evidence of this occurrence, a mandatory service bulletin (SB32-3134) was released in July 1999 requiring non-destructive inspection of the torque knees at reduced intervals. Per the SB, the mandatory inspection was to be accomplished within the next 100 cycles (1 cycle = 1 landing) or next scheduled inspection for MLG torque knees with accumulated time in service of 1,000 hours. Recurring inspections were required every 1,000 cycles or 2 years, which ever occurred first. An additional service bulletin (SB 32-3116) was released in October 1999 recommending a steel torque knee replacement for the upper and lower torque knees and removed the 1,000 cycle/2-year inspection requirement for SB 32-3134. On February 22, 2002, the FAA issued airworthiness directive 2002-01-10 which required the repetitive inspection and/or replacement of the torque knees per the SBs.
A review of the aircraft records revealed the upper torque knee underwent florescent penetrant inspection on March 25, 2016; airframe total time: 11,230.4/Landings 10,505, and on February 10, 2017; time and landings unknown. At the time of the accident, the airframe total time was 11,423.5 hours and 10,715 landings.
History of Flight
Takeoff Part(s) separation from AC (Defining event)
Landing Abnormal runway contact
Pilot Information
Certificate: Airline transport; Flight instructor
Age: 64,Male
Airplane Rating(s): Single-engine land; Multi-engine land
Seat Occupied: Left
Other Aircraft Rating(s): None
Restraint Used: 4-point
Instrument Rating(s): Airplane
Second Pilot Present: Yes
Instructor Rating(s): Airplane single-engine; Instrument airplane
Toxicology Performed: No
Medical Certification: Class 1 Without waivers/limitations
Last FAA Medical Exam: December 27, 2018
Occupational Pilot: Yes
Last Flight Review or Equivalent: February 27, 2019
Flight Time: 7226 hours (Total, all aircraft), 200 hours (Total, this make and model), 4438 hours (Pilot In Command, all aircraft), 11 hours (Last 90 days, all aircraft), 9 hours (Last 30 days, all aircraft)
Flight instructor Information
Certificate: Airline transport
Age: 38,Male
Airplane Rating(s): Single-engine land; Multi-engine land
Seat Occupied: Right
Other Aircraft Rating(s): None
Restraint Used: 4-point
Instrument Rating(s): Airplane
Second Pilot Present: Yes
Instructor Rating(s): None
Toxicology Performed: No
Medical Certification: Class 1 With waivers/limitations
Last FAA Medical Exam: October 8, 2018
Occupational Pilot: Yes
Last Flight Review or Equivalent: March 13, 2019
Flight Time: 8094 hours (Total, all aircraft), 112 hours (Total, this make and model), 5668 hours (Pilot In Command, all aircraft), 32 hours (Last 90 days, all aircraft), 7 hours (Last 30 days, all aircraft)
Aircraft and Owner/Operator Information
Aircraft Make: Beech
Registration: N176TW
Model/Series: E90
Aircraft Category: Airplane
Year of Manufacture: 1974
Amateur Built: No
Airworthiness Certificate: Normal
Serial Number: LW-76
Landing Gear Type: Retractable - Tricycle
Seats: 8
Date/Type of Last Inspection: January 14, 2018 AAIP
Certified Max Gross Wt.: 10160 lbs
Time Since Last Inspection:
Engines: 2 Turbo prop
Airframe Total Time: 11400.4 Hrs as of last inspection
Engine Manufacturer: Pratt & Whitney
ELT: C126 installed, not activated
Engine Model/Series: PT6A-28
Registered Owner:
Rated Power: 550 Horsepower
Operator:
Operating Certificate(s) Held: On-demand air taxi (135)
Operator Does Business As:
Operator Designator Code: HAEA
Meteorological Information and Flight Plan
Conditions at Accident Site: Visual (VMC)
Condition of Light: Day
Observation Facility, Elevation: AFW,723 ft msl
Distance from Accident Site: 0 Nautical Miles
Observation Time: 16:53 Local
Direction from Accident Site: 0°
Lowest Cloud Condition: Scattered / 6000 ft AGL
Visibility: 10 miles
Lowest Ceiling: None
Visibility (RVR):
Wind Speed/Gusts: 13 knots / 21 knots
Turbulence Type Forecast/Actual: None / None
Wind Direction: 360°
Turbulence Severity Forecast/Actual: N/A / N/A
Altimeter Setting: 29.97 inches Hg
Temperature/Dew Point: 31°C / 16°C
Precipitation and Obscuration: No Obscuration; No Precipitation
Departure Point: Greenville, TX (GVT)
Type of Flight Plan Filed: VFR
Destination: Fort Worth, TX (AFW)
Type of Clearance: Traffic advisory; VFR flight following
Departure Time:
Type of Airspace: Class D
Airport Information
Airport: Fort Worth Alliance Airport AFW
Runway Surface Type: Concrete
Airport Elevation: 723 ft msl
Runway Surface Condition: Dry
Runway Used: 34L IFR Approach: None
Runway Length/Width: 11010 ft / 150 ft
VFR Approach/Landing: Full stop
Wreckage and Impact Information
Crew Injuries: 3 None
Aircraft Damage: Substantial
Passenger Injuries:
Aircraft Fire: None
Ground Injuries: N/A
Aircraft Explosion: None
Total Injuries: 3 None
Latitude, Longitude: 33.069999,-96.065277(est)
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