ERA21LA388 · Cessna 172 S
Aviation Pacific Flight Training School Cessna 172 S · Accident: loss of engine power (total) en route
From Gainesville Regional Airport (GNV) to Massey Ranch Airpark (X50)
Event
- NTSB case
- ERA21LA388
- 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
- Event fatalities
- Unknown
- 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
Cessna 172 S
- 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
- N116SV
- Onboard fatalities
- Unknown
- Route
- From Gainesville Regional Airport (GNV), Gainesville, FLTo Massey Ranch Airpark (X50), New Smyrna Beach, FL
- Aircraft age
- About 16 years (built 2005)
- 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 · descent
- 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 (total)
- 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
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
After an uneventful 1-hour flight, the flight instructor and student pilot were returning to the airplane’s home base. The flight instructor pointed out to the student that the airplane had descended below the assigned altitude, and the student replied, “we have no power.” The flight instructor took over the flight controls and attempted to restore power. Because that effort was unsuccessful, the flight instructor pitched the airplane to achieve the best glide speed. After realizing that the airplane would not reach the nearest airport, he performed a forced landing in a field, and the airplane nosed over during the landing roll.
Postaccident examination of the engine revealed that the camshaft was not being driven by the left crankshaft idler gear assembly because it was out of position. The nut that secured the idler gear to a stud at the left crankcase was separated, and a bolt that also secured the idler gear to the left crankcase was fractured. Extensive damage was noted to the left crankcase in the area that supported the idler gear and the area into which the securing bolt was threaded, indicating movement of the crankshaft idler gear shaft for an extended period of time. The available evidence for this investigation did not allow a determination regarding the reason for the separation of the nut from the stud and the fracture of the bolt that secured the idler gear to the crankcase. The engine was last overhauled about 11 years and 3,488 hours before the accident. The owner/operator of the airplane at the time of the accident stated that, during the time that he owned the airplane, maintenance personnel had not cut open the oil filter to inspect the filter element during each oil change. Photographic evidence showed the presence of non-ferrous particles in the oil filter element. It is likely that these particles were from the damaged left crankcase. If maintenance personnel had cut open the oil filter and inspected the filter element during each oil change (the most recent of which was during the last inspection of the engine 3 months before the accident), it is possible that they would have detected the presence of non-ferrous particles in the filter element and taken action to identify the source.
Probable cause
The separation of the nut from the stud and the fracture of the bolt that secured the crankshaft idler gear to the engine crankcase, which resulted in a total loss of engine power due to the inability of the left crankshaft idler gear assembly to drive of the camshaft.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record ERA21LA388
- Event ID
- 20210930103998
- Case number
- ERA21LA388
- 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, cause areas. 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: f2904b02185119b4e093295a9c68610c291875c6cca7a939faad06f27f1f0407; retrieved 2026-09-16T14:36:12.573Z.