CHI99LA162 · Grumman-Schweizer G-164B
Central Valley Aviation Grumman-Schweizer G-164B · Accident: partial loss of engine power (mechanical failure) en route
From Hought Airstrip (NA18) to an unrecorded destination
Event
- NTSB case
- CHI99LA162
- 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
Grumman-Schweizer G-164B
- Aircraft type
- Grumman Schweizer G-164
- 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
- N6524K
- Operator
- Central Valley Aviation
- Onboard fatalities
- Unknown
- Route
- From Hought Airstrip (NA18)To not recorded
- 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 137: Agricultural
- 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, cylinder › Separation
- Pilot in command › Visual lookout, not possible
- Terrain condition › Drop-off/descending embankment
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
The pilot said the engine began to run rough during cruise. Then the engine blew smoke and oil and the windshield became covered with oil. The pilot turned the airplane towards the airport. On the approach to runway 09, the pilot had no visibility through the oil and the airplane had run off a road leading to the runway's centerline and an embankment in the safety area before the approach end of runway 09 during his forced landing. The airplane came to rest inverted next to the embankment. The number one cylinder head was found separated from its cylinder and was inspected. The inspection revealed no indications of preexisting cracks in the cylinder head. The separation occurred in the combustion dome between the cylinder head and the screw on cylinder barrel. The cylinder head revealed marks and dents consistent with piston ring or piston crown contact.
Probable cause
the number one cylinder's separation, the pilot's visual lookout not possible through the oil given off by the number one cylinder, and the embankment. A factor in the accident was the oil.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record CHI99LA162
- Event ID
- 20001212X18730
- Case number
- CHI99LA162
- 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: a278df5cf80f90415681c102dcc5f7e0032d0c452e72547df5987f8fda8ea143; retrieved 2026-09-22T15:04:28.388Z.