Kolb KOLB TWINSTAR TSP 1 accident near Hector, Minnesota, June 13, 2019
On June 13, 2019 at about 2:50 pm local time, a 1986 Kolb KOLB TWINSTAR TSP 1, an amateur-built aircraft,, registered N217JM, was substantially damaged in an accident during landing near Hector, Minnesota (Hector Muni airport). It was a flight test under general aviation rules (Part 91). No one was hurt; 1 person was on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The pilot’s operation of the airplane outside of the center of gravity limits, which resulted in an adverse aerodynamic condition and subsequent hard landing. Contributing to the accident was the pilot’s incorrect calculations of the airplane’s CG limits.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- June 13, 2019 · about 2:50 pm local time
- Place
- Hector, Minnesota · Hector Muni · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Kolb KOLB TWINSTAR TSP 1 III, built 1986, amateur-built
- Registration
- N217JM · no longer on the register · serial A-2
- Damage
- Substantial damage
- Flight
- Flight test · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The pilot was conducting a maintenance test flight and had been in the air about 15 minutes when airplane began to oscillate up and down. He had difficulty maintaining control, so he made a rapid descent toward the airport. During the rapid descent the oscillation and shaking reduced, but as he decreased the descent rate, the airplane oscillated violently. The airplane landed hard on the grass runway. The airplane sustained substantial damage to the wings, fuselage, and empennage. After the accident, the pilot stated that he thought the tail boom had fractured inflight. A postaccident examination of the airframe revealed that the tubular empennage structure had fractured and was separated. An examination of the fractured section determined that the fractures were due to overstress as a result of the hard landing. A review of the pilot’s calculated weight and balance information revealed that the pilot had incorrectly calculated the weight and balance and that the airplane’s center of gravity (CG) was aft of manufacturer limitations. After the accident, the pilot reported that he was adjusting his CG while airborne, and he placed a bag of bird seed in the passenger seat to assist during the inflight test. The bag was aft of the datum per the manufacturers specifications and would have moved the CG further aft. This likely resulted in an adverse aerodynamic condition and an uncontrollable pitch oscillation.
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
- Hard landing during landing defining event
The NTSB's findings
- cause Personnel issues › Task performance › Use of equip/info › Aircraft control › Pilot
- Aircraft › Aircraft oper/perf/capability › Aircraft capability › CG/weight distribution › Capability exceeded
Pilot
- Certificate: commercial pilot
- Ratings: multi-engine land; single-engine land; single-engine sea; instructor: instrument airplane; rotorcraft: helicopter
- Medical certificate: Class 3 (with waivers/limitations)
- Seat: left
- Injury: no injuries
The aircraft
- Airframe total time: 113 hours
- Last inspection: condition inspection, June 2, 2019; 0 hours since
- Seats: 2
- Landing gear: fixed
- Engine: Rotax 503 DCDI (piston); 0 hours total
The flight
- Departed from: 1D6 Hector MN at 2:30 pm
- Flight plan: none
- Runway 05, 2,580 ft by 165 ft
Weather at the time
- Light: daylight
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 0°F (-18°C), dew point 0°F (-18°C)
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
10 documents, released by the NTSB on October 29, 2021. 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 | PDF, 9 pages | View Download |
| 2 | FAA Inspector's Statement - Center of Gravity | PDF, 1 page | View Download |
| 3 | FAA Center of Gravity Envelope Calculation | PDF, 1 page | View Download |
| 4 | Kolb Weight and Balance Information | PDF, 2 pages | View Download |
| 5 | Correspondence - Email to NTSB | PDF, 2 pages | View Download |
| 6 | Correspondence - Email to FAA | PDF, 3 pages | View Download |
| 7 | Video File - Hard Landing | video | View Download |
| 8 | Materials Laboratory Factual Report 19-041 | PDF, 5 pages | View Download |
| 9 | Drawings (Engineering Sketches) | PDF, 2 pages | View Download |
| 10 | Photos | PDF, 4 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.