LAX99LA287 · Mooney M20J
Mooney M20J · Accident: total loss of engine power (mechanical failure) en route
From KWGF · Palmdale, CA to Truckee Tahoe Airport (KTRK)
Event
- NTSB case
- LAX99LA287
- 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 M20J
- 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
- N4201S
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From KWGF · Palmdale, CATo Truckee Tahoe Airport (KTRK), Truckee, 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
- 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
- Total 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 › Fatigue
- Engine assembly, cylinder › Separation
- Other maintenance personnel › Inadequate quality control
- Other maintenance personnel › Maintenance, overhaul, major, improper
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
The pilot was at cruise altitude of 9,500 feet when he heard a loud metallic bang. The airframe began to shake violently and the engine started running rough immediately following the noise. The pilot turned toward a nearby airport and the engine suddenly quit. The pilot was able to glide to the airport and touched down on the 3,300-foot-long runway; however, he had carried extra speed on the approach to allow a maneuvering margin to miss a large ravine off the runway's approach end. The airplane ran off the end of the runway and subsequently struck scrub bush. Postaccident examination of the engine revealed that the number three cylinder had separated in half between the Nos. 9 and 10 cooling fins. Metallurgical examination disclosed that the fracture was due to a fatigue crack, which had emanated from a notch and groove on the outer radius of one cooling fin. The notch and groove were painted the same color as the engine. The engine was overhauled 16 hours prior to the accident with 3 new cylinders installed, including the failed one.
Probable cause
The fatigue failure and separation of the number three cylinder due to the cylinder overhaul facility's improper inspection and quality control processes.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record LAX99LA287
- Event ID
- 20001212X19570
- Case number
- LAX99LA287
- 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: e081d2878fe389a65b6763df6fef4efdc120c14c28daf2b8ed1f0fd42022f842; retrieved 2026-09-21T20:24:37.783Z.