CHI97LA142 · Mooney M20F
Mooney M20F · Accident: partial loss of engine power (mechanical failure) en route
From Chicago Executive Airport (PWK) to Dane County Regional Truax Field (MSN)
Event
- NTSB case
- CHI97LA142
- 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
- 0
- 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
Mooney M20F
- Aircraft type
- Mooney M20
- Category
- Airplane
- 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
- N6950V
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Chicago Executive Airport (PWK)To Dane County Regional Truax Field (MSN), Madison, WI
- Aircraft age
- Not recorded
- 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
- En route · climb to cruise
- First occurrenceThe 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
- Partial loss of engine power (mechanical failure)
- 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
- Engine assembly, valve, exhaust › Binding(mechanical)
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
On the first flight after maintenance, the pilot reported that on the initial climb, 'the engine stopped producing power and began behaving erratically.' The pilot declared an emergency to the controlling ATC personnel, and turned back to Palwaukee Municipal Airport. The pilot reported that the engine, 'was backfiring and sounded like only one cylinder was hitting.' The pilot selected a field to execute a forced landing, circled it twice, and landed on an easterly heading. The pilot reported that the plane, after touch down, 'skidded and rolled for about 250 yards before coming to rest on the bank of a small creek.' The pilot evacuated the airplane and waited for assistance. Examination of the number four cylinder revealed excessive black carbon build-up on the cylinder head and exhaust valve seat.
Probable cause
binding of the number four exhaust valve, which resulted in a partial power loss. A factor was the ravine.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record CHI97LA142
- Event ID
- 20001208X07881
- Case number
- CHI97LA142
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
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. 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: 987d0a52d9b514a56f1ea8adff5effbcfb30c5af66fbf1ebeded5237db3ec189; retrieved 2026-09-22T19:38:20.471Z.