Amateur-built Xenon 4 accident near Knoxville, Iowa, April 17, 2017
On April 17, 2017 at about 6:41 pm local time, a 2016 amateur-built Xenon 4 (gyroplane), registered N912XV, was substantially damaged in an accident during initial climb near Knoxville, Iowa (Knoxville Municipal airport). It was a personal 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
A partial loss of engine power for reasons that could not be determined based on the available information. Contributing to the accident was the failure of the owners to obtain proper materials regarding the operation and maintenance of the engine.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- April 17, 2017 · about 6:41 pm local time
- Place
- Knoxville, Iowa · Knoxville Municipal · map
- Type
- Accident
- Injuries
- No one was hurt; 2 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Amateur-built Xenon 4, built 2016
- Registration
- N912XV · no longer on the register · serial CAM14M2E02AA023
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The sport pilot reported that the takeoff in the experimental, amateur-built gyroplane was normal; however, while continuing to climb through 500 ft above ground level, the aircraft stopped climbing and started to descend. The pilot-rated passenger reported hearing a decrease in engine power, but the engine continued to operate. The pilot started to turn back to the airport, then chose to land in a field. He saw a powerline and he turned sharply; the gyroplane hit the powerline then fell and impacted the side of a ditch. The gyroplane kit manufacturer installed a turbocharged, 135-hp Rotax 912 ULST that was modified from the 100-hp Rotax 912 ULS engine. During a postaccident examination, the engine started without hesitation and was run at idle power, but only for a brief time, since the propeller was broken. The brother of the accident pilot, who was a co-owner of the aircraft, reported that the engine had a history of not developing full power. He stated that the engine would develop about 3,500 rpm instead of developing full power at 5,200 to 5,300 rpm. On numerous occasions, he adjusted the manifold pressure probe by trial and error to get the engine to develop full power. The engine would operate properly, then the problem would reoccur, and he would repeat the process. The gyroplane had operated successfully for 7.9 hours since the last time the engine had not produced full power until the time of the accident. The owners reported that they did not understand the operation of the turbocharged engine or its associated components, and that the kit manufacturer did not provide operating manuals that explained the operation of the gyroplane or its turbocharged engine.
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
- Loss of engine power (partial) during initial climb defining event
- Collision with terrain or object (not controlled flight into terrain) during initial climb
- Collision with terrain or object (not controlled flight into terrain) during uncontrolled descent
The NTSB's findings
- cause Aircraft › Aircraft power plant › Turbocharging (recip only) › Turbocharger › Malfunction
- cause Aircraft › Aircraft power plant › Turbocharging (recip only) › Turbocharger › Incorrect service/maintenance
- cause Aircraft › Aircraft power plant › Turbocharging (recip only) › Turbocharger › Related maintenance info
- cause Personnel issues › Experience/knowledge › Knowledge › Knowledge of procedures › Pilot
- cause Personnel issues › Experience/knowledge › Knowledge › Knowledge of procedures › Owner/builder
- cause Personnel issues › Experience/knowledge › Knowledge › (general) › Not specified
- factor Organizational issues › Development › Manufacture/production › Document/info production › Manufacturer
- factor Organizational issues › Development › Selection/certification/testing › Equip certification/testing › Manufacturer
- Organizational issues › Support/oversight/monitoring › Oversight › Oversight of reg compliance › FAA/Regulator
Pilot
- Certificate: sport pilot
- Ratings: rotorcraft: gyroplane
- Flight time: 121 hours in all; 121 in this make and model; 8 in the last 90 days; 3 in the last 30 days; 121 as pilot in command
- Medical certificate: Sport Pilot
- Seat: left
- Injury: no injuries
Pilot-Rated Passenger
- Certificate: flight instructor, commercial pilot
- Ratings: single-engine land; instructor: airplane single-engine; instrument: airplane
- Flight time: 1,100 hours in all; 0 in this make and model
- Medical certificate: Class 2 (without waivers/limitations)
- Seat: rgt
- Injury: no injuries
The aircraft
- Airframe total time: 300 hours
- Last inspection: 100-hour inspection, November 11, 2016
- Maximum gross weight: 1,320 lb
- Seats: 2
- Landing gear: fixed
- Engine: Rotax 912 ULS-T (piston); 300 hours total
The flight
- Departed from: OXV Knoxville IA at 6:36 pm
- Destination: OXV Knoxville IA
- Flight plan: none
- Runway 15, 4,000 ft by 75 ft
- A second pilot was aboard
Weather at the time
- Light: daylight
- Wind: from 290° at 4 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 70°F (21°C), dew point 37°F (3°C)
- Altimeter: 30.13 inHg
- Observation at 6:35 pm from PEA, 10 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 | |||
| Passengers | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
11 documents, released by the NTSB on April 16, 2018. 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, 10 pages | View Download |
| 2 | Passenger Statement | PDF, 1 page | View Download |
| 3 | NTSB Record of Conversations | PDF, 8 pages | View Download |
| 4 | FAA and Witness Emails | PDF, 2 pages | View Download |
| 5 | Aerial View of Accident Site | PDF, 1 page | View Download |
| 6 | Maintenance and Pilot Logbook Excerpts | PDF, 16 pages | View Download |
| 7 | Aircraft Information | PDF, 8 pages | View Download |
| 8 | Celier Rotax 912 Ulst Information | PDF, 1 page | View Download |
| 9 | FAA Certification for Amateur-built Aircraft | PDF, 2 pages | View Download |
| 10 | FAA Amateur-built Gyrocopter Checklist | PDF, 9 pages | View Download |
| 11 | Investigations Photos | PDF, 20 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.