- Date
- June 28, 2022, 10:30 local (14:30 UTC)
- Place
- Knoxville, TN
- Injuries
- 2 uninjured
- Damage
- Substantial damage
- Phase of flight
- Landing
- Aircraft
- N721SDAmerican Champion 8KCAB
- Defining event
- Landing: Sys/Comp malf/fail (non-power)
- Weather
- Visual (VMC) · Day
- Status
- Completed
- Report
- Approved by Office Director
- Investigation class
- Class 4 - Basic report with no Prelim publish
- NTSB office
- Eastern Region Aviation
- Parties
- FAA-FSDO
- Case key
- 105404
From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.
On this page
Probable cause
The inadequate maintenance of the left main landing gear through bolt, which resulted in a left main landing gear collapse and subsequent runway excursion during landing.
Findings · 2
NTSB’s coded findings. Those marked are part of the probable cause; the rest are factors or other findings. Under each, the cases with the same finding.
Sequence of events
The events NTSB coded, in order, by phase of flight. The defining event is the one that best describes the accident. Under each, the cases with the same event anywhere in their sequence.
Analysis
After performing maneuvers in the local area, the pilot receiving instruction and the flight instructor returned to the departure airport and performed two practice landings. During the third landing, the flight instructor heard a “bang” noise and the airplane veered left away from the runway centerline. The airplane came to rest in the grass next to the runway and the airplane’s fuselage and rudder were substantially damaged. A Federal Aviation Administration inspector examined the airplane after the accident. The airplane’s left main landing gear had collapsed and the inspector found that the left main landing gear through bolt was fractured. The inspector further reported that the airplane’s most recent annual inspection had been completed more than 22 months before the accident. Additionally, the airframe manufacturer’s maintenance manual required that the through bolt be removed and inspected at every 100 hour/annual inspection and replaced as necessary, in addition to a mandatory replacement every 500 hours. The airplane’s maintenance records did not show when the last though bolt change had occurred. Based on this information, it is likely that the landing gear collapsed due to a failure of the left main landing gear through bolt, and that the through bolt had likely not been maintained in accordance with the airframe manufacturer’s requirements.
Aircraft
- Registration
- N721SD
- Reported as
- American Champion 8KCAB
- Category
- Airplane
- Serial number
- 722-93
- Built
- 1993
- Airframe hours
- 2,318
- Engine
- Lycoming IO-360, 180 horsepower, reciprocating
- Damage
- Substantial damage
- Flight
- Instructional · Part 91
- Operator
- Super D Aviation Training Co LLC
- Registered owner
- Super D Aviation Training Co LLC
- Airworthiness certificate
- Standard, Aerobatic; Standard, Normal
- Last inspection
- Annual · August 1, 2020 · 170 hours before
- Airport
- DKX · Knoxville Downtown Island, runway 8, 3,499 × 75 ft, asphalt
- Equipment
- Stall warning system, ADS-B
Flight crew · 2
As NTSB recorded them. NTSB leaves out names.
- Role
- Pilot
- Age
- 20
- Injuries
- None
- Certificate
- Private
- Airplane ratings
- Single-engine land
- Medical
- Class 2, Without waivers/limitations
- Last flight review
- August 19, 2021
- Seat
- Front
- Flight hours
- 63.1 total · 2.7 in this make and model · 16.8 as pilot in command · 5.9 in the last 90 days · 2.7 in the last 30 days
- Role
- Flight instructor
- Age
- 73
- Injuries
- None
- Certificates
- Military, Commercial, Airline transport, Flight instructor, Flight engineer
- Airplane ratings
- Single-engine land, Multi-engine land
- Instrument ratings
- Airplane
- Medical
- Class 3, With waivers/limitations
- Last flight review
- February 2, 2022
- Seat
- Rear
- Restraint
- 3-point
- Flight hours
- 25,000 total · 1,000 in this make and model · 20,000 as pilot in command · 200 in the last 90 days · 80 in the last 30 days · 3 in the last 24 hours
Weather
- Conditions
- Visual (VMC) · Day
- Visibility
- 10 statute miles
- Lowest ceiling
- None
- Temperature
- 75 °F, dew point 59 °F
- Altimeter
- 30.21 inHg
- Observed at
- DKX
- METAR
- METAR KDKX 281415Z AUTO VRB04KT 10SM CLR 24/15 A3021 RMK A01
Docket · 5
The files NTSB released with the investigation on June 23, 2023, on NTSB’s docket system: statements, records, photos and specialists’ reports. 8.6 MB in all.