LAX96LA180 · Cessna 320
Cessna 320 · Accident: partial loss of engine power (mechanical failure) during initial climb
From Mammoth Yosemite Airport (MMH) to Q99 · San Martin, CA
Event
- NTSB case
- LAX96LA180
- 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 320
- Aircraft type
- Cessna 320
- 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
- N5752X
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Mammoth Yosemite Airport (MMH)To Q99 · San Martin, CA
- 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
- Initial climb
- 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
- Exhaust system, turbocharger › Pressure too low
- Exhaust system, wastegate › Binding(mechanical)
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
The pilot performed a static engine run-up, and with no discrepancies noted, he commenced the takeoff. Upon reaching between 25 and 50 feet above the runway during the initial climb, the normal 35 inches of manifold pressure (MP) was observed being produced by the left engine. However, the right engine only produced between 18 and 20 inches of MP. The airplane veered right and settled into the rough/uneven terrain near the airport. The airport's elevation is 7,128 feet mean sea level, and the calculated density altitude was over 8,200 feet. An examination of the right engine's turbocharger assembly revealed the absolute pressure controller was set lower than the manufacturer's specifications required. Also, the wastegate butterfly valve was mechanically binding in its housing and would not fully close.
Probable cause
the partial failure of the right engine turbocharger wastegate butterfly valve to fully close due to mechanical binding and the low setting of its associated absolute pressure controller. A related factor was the high density altitude which reduced the engine's ability to produce adequate manifold pressure.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record LAX96LA180
- Event ID
- 20001208X05623
- Case number
- LAX96LA180
- 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: 6f77166e80377b55985f9424b8d1cc56df6392f498db03fe292161f8397d19a3; retrieved 2026-09-22T22:33:59.885Z.