FTW93LA216 · Cessna 172N
Cessna 172N · Accident: partial loss of engine power (mechanical failure) en route
From University of Oklahoma Westheimer Airport (OUN) to Gainesville Municipal Airport (GLE)
Event
- NTSB case
- FTW93LA216
- 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
Cessna 172N
- Aircraft type
- Cessna 172
- 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
- N4884G
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From University of Oklahoma Westheimer Airport (OUN), Norman, OKTo Gainesville Municipal Airport (GLE), Gainesville, TX
- 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 · 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, rocker arm/tappet › Fatigue
- Engine assembly, rocker arm/tappet › Separation
- Terrain condition › None suitable
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
THE AIRPLANE COLLIDED WITH ROUGH TERRAIN DURING A NIGHT FORCED LANDING FOLLOWING A PARTIAL POWER LOSS. THE ACCIDENT OCCURRED DURING A NIGHT DUAL INSTRUCTIONAL FLIGHT AND THE INSTRUCTOR MADE THE FORCED LANDING. INVESTIGATION REVEALED THAT THE #3 EXHAUST VALVE ROCKER ARM ATTACHMENT STUD HAD FAILED IN FATIGUE. THE SEPARATED STUD SUBSEQUENTLY LODGED UNDER THE #3 INTAKE VALVE MECHANISM AND THE CORRESPONDING PUSH ROD WAS BENT. THE ENGINE AND SUBJECT PARTS HAD ACCUMULATED A TOTAL OF 2,903.5 HOURS.
Probable cause
THE LACK OF SUITABLE TERRAIN ONTO WHICH TO EXECUTE THE FORCED LANDING WHICH WAS NECCESITATED BY THE PARTIAL POWER LOSS. THE POWER LOSS WAS A RESULT OF THE FATIGUE FAILURE OF THE EXHAUST VALVE ROCKER ARM ATTACHMENT STUD. A FACTOR WAS THE NIGHT CONDITIONS.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record FTW93LA216
- Event ID
- 20001211X12922
- Case number
- FTW93LA216
- 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: local date, investigation status. Values present in the bulk record are kept.
- The date is the local date; the NTSB stores the UTC date 1993-07-25.
- API snapshot SHA-256: 5950459c9a5e1ac7b98bfa5ead6a4d2debac746285ab3cd6c6d767fda5c86887; retrieved 2026-09-23T01:50:27.567Z.