CEN17LA156 · Loomis Xenon 4
Loomis Xenon 4 · Accident: loss of engine power (partial) during initial climb
From Knoxville Municipal Airport (OXV) to Knoxville Municipal Airport (OXV)
Event
- NTSB case
- CEN17LA156
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Accident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- API-reported fatalities
- 0 · all aircraft and ground
- Ground fatalities
- Unknown
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- General aviation
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Visual Meteorological Cond
Loomis Xenon 4
- Aircraft type
- Loomis XENON 4
- Category
- Gyroplane
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N912XV
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Knoxville Municipal Airport (OXV), Knoxville, IATo Knoxville Municipal Airport (OXV), Knoxville, IA
- Aircraft age
- About 1 year (built 2016)
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 91: General Aviation
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- Initial climb
- Defining eventThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- Loss of engine power (partial)
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Substantial
Cause areas
- Aircraft › Aircraft power plant
- Personnel issues › Experience/knowledge
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
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.
Probable cause
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.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record CEN17LA156
- Event ID
- 20170418X92855
- Case number
- CEN17LA156
- Dataset
- full-current
- Source SHA-256
- 5cf380f0061817c0331a6b2d8cc7e0ee3a79bea469a1001dc5c10e56f35f5ab3
Source notes (4)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: investigation status, coordinates. Values present in the bulk record are kept.
- The date is the local date, which is the same as the UTC date the NTSB stores.
- API snapshot SHA-256: c052b2463df3dcb39e9702ff0beedb779a8ae979acf227addb8c66b7a4ca5b97; retrieved 2026-09-16T05:10:46.438Z.