American Champion Aircraft 8KCAB accident near Knoxville, Tennessee, June 28, 2022
On June 28, 2022 at about 2:30 pm local time, a 1993 American Champion Aircraft 8KCAB, registered N721SD, was substantially damaged in an accident during landing near Knoxville, Tennessee (Knoxville Downtown Island airport). It was an instructional flight under general aviation rules (Part 91). No one was hurt; 2 people were on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
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.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- June 28, 2022 · about 2:30 pm local time
- Place
- Knoxville, Tennessee · Knoxville Downtown Island · map
- Type
- Accident
- Injuries
- No one was hurt; 2 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- American Champion Aircraft 8KCAB, built 1993 · all 8KCABs on the register
- Registration
- N721SD · no longer on the register · serial 722-93
- Damage
- Substantial damage
- Flight
- Instructional flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
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.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
What happened, in order
- Landing gear collapse during landing
- Sys/Comp malf/fail (non-power) during landing defining event
The NTSB's findings
- Aircraft › Aircraft systems › Landing gear system › Main landing gear attach sec › Failure
- Personnel issues › Task performance › Maintenance › Scheduled/routine maintenance › Maintenance personnel
Pilot
- Certificate: private
- Ratings: single-engine land
- Flight time: 63.1 hours in all; 2.7 in this make and model; 5.9 in the last 90 days; 2.7 in the last 30 days; 16.8 as pilot in command
- Last flight review: August 19, 2021
- Medical certificate: Class 2 (without waivers/limitations)
- Seat: frt
- Injury: no injuries
Flight instructor
- Certificate: airline transport pilot, flight instructor, commercial pilot, flight engineer, military
- Ratings: multi-engine land; single-engine land; instructor: airplane multi-engine; instructor: airplane single-engine; instructor: instrument airplane; instrument: airplane
- Flight time: 25,000 hours in all; 1,000 in this make and model; 200 in the last 90 days; 80 in the last 30 days; 20,000 as pilot in command; 10,000 on instruments
- Last flight review: February 2, 2022
- Medical certificate: Class 3 (with waivers/limitations)
- Seat: rear
- Injury: no injuries
The aircraft
- Airframe total time: 2,318 hours
- Last inspection: annual inspection, August 1, 2020; 170 hours since
- Maximum gross weight: 1,800 lb
- Seats: 2
- Landing gear: fixed
- Engine: Lycoming IO-360 (piston); 300 hours total
- Operator: Super D Aviation Training CO LLC
The flight
- Flight plan: none
- Runway 8, 3,499 ft by 75 ft
- A second pilot was aboard
Weather at the time
- Light: daylight
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 75°F (24°C), dew point 59°F (15°C)
- Altimeter: 30.21 inHg
- Observation at 10:15 am from DKX
Weather report (METAR): METAR KDKX 281415Z AUTO VRB04KT 10SM CLR 24/15 A3021 RMK A01
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 2 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
5 documents, released by the NTSB on June 23, 2023. View them here, or download them; the NTSB redacts some personal details before release, and this site shows the NTSB's own titles rather than its file names.
| # | Document | What it is | |
|---|---|---|---|
| 1 | Pilot/operator Aircraft Accident Report, NTSB Form 6120.1 - Student Pilot | PDF, 9 pages | View Download |
| 2 | Pilot/operator Aircraft Accident Report, NTSB Form 6120.1 - Flight Instructor | PDF, 11 pages | View Download |
| 3 | Witness Statement | PDF, 1 page | View Download |
| 4 | Memorandum for Record A�� FAA Inspector's Statement | PDF, 1 page | View Download |
| 5 | Photographs | PDF, 7 pages | View Download |
The same docket at the NTSB · documents without a copy here are fetched from the NTSB when you open them.
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.