LAX99FA270 · Beech J35
Beech J35 · Accident: total loss of engine power (mechanical failure) en route
From San Rafael, CA to U35 · Caldwell, ID
Event
- NTSB case
- LAX99FA270
- 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
Beech J35
- Aircraft type
- Beechcraft 35
- 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
- N4932B
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From San Rafael, CATo U35 · Caldwell, ID
- 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)
- Also codedOther events the NTSB coded in the sequence, such as a wire strike after a loss of power. Flight Findings uses them for its kinds of event. Glossary
- Tree(s)
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Destroyed
Cause areas
- Other maintenance personnel › Maintenance, top overhaul, improper
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
The pilot radioed that the aircraft's engine was failing and he was altering his course to land at the nearest airport. While on left base leg for landing, the cowling flew open, oil filled the windshield, and the engine ceased delivering power. The aircraft impacted a tree and came to rest in a city park. At the scene, the No. 6 engine cylinder was separated from the crankcase and engine components associated with that cylinder were found over a 40-foot radius around the aircraft. The engine crankcase where the No. 6 cylinder attached was broken away at the 12 o'clock position; the upper forward, upper rear, and lower rear mounting studs were broken; and the lower forward stud and the two lower center studs were present. The skirt of the No. 6 cylinder exhibited a pattern of longitudinal striations where it mated into the crankcase opening. At the lower left of the cylinder mount location was a small ledge of material, which approximated the shape of the circumference of the cylinder base flange. Opposite this location, on the upper right of the cylinder mounting location, was a brightly polished wear area. The engine received a top overhaul 7 months, 41.8 hours prior to the accident. Breakaway torque was measured on the remaining cylinder base nuts and found to range between 25 and 40 foot-pounds; the specification torque values are between 40.8 and 42.5.
Probable cause
A loss of engine power due to improperly torque cylinder base nuts by maintenance personnel during a top overhaul.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record LAX99FA270
- Event ID
- 20001212X19548
- Case number
- LAX99FA270
- 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: 3715bbbe4fd34addefb3121d0f6dd597fbb5a5de5a0247c9b8c08d4c99a17de8; retrieved 2026-09-21T10:54:03.281Z.