LAX90LA015 · Grumman AA-1A
Grumman AA-1A · Accident: total loss of engine power (mechanical failure) en route
From Borrego Valley Airport (L08) to Montgomery-Gibbs Executive Airport (MYF)
Event
- NTSB case
- LAX90LA015
- 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 AA-1A
- Aircraft type
- Grumman AA-1
- 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
- N9330L
- Operator
- John L. Lee · private individual
- Onboard fatalities
- Unknown
- Route
- From Borrego Valley Airport (L08), Borrego Springs, CATo Montgomery-Gibbs Executive Airport (MYF), San Diego, 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, valve, exhaust › Failure, total
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
THE 23-YEAR-OLD RECENTLY CERTIFIED PRIVATE PILOT PURCHASED AN 18-YEAR-OLD FLYING CLUB AIRPLANE. THE AIRCRAFT AND ENGINE HAD BEEN OPERATED FOR A TOTAL OF 2093 HOURS. NO RECORD WAS FOUND OF THE ENGINE HAVING BEEN OVERHAULED. DURING THE AIRCRAFT'S LIFE, IT HAD BEEN INACTIVE FOR TWO PERIODS TOTALING 8 YEARS. DURING CRUISE FLIGHT, THE ENGINE LOST ALL POWER. THE PILOT MADE AN EMERGENCY LANDING IN THE DESERT, AND THE AIRCRAFT COLLIDED WITH A BERM AND NOSED OVER. EXAMINATION OF THE ENGINE, WHICH HAD A TBO OF 2400 HOURS IF KEPT IN CONTINOUS SERVICE, REVEALED THAT THE NO. 1 EXHAUST VALVE HEAD HAD SEPARATED FROM THE STEM WHICH WAS NECKED DOWN AT THE POINT OF FAILURE. THE ENGINE'S THREE OTHER EXHAUST VALVE STEMS WERE ALSO FOUND NECKED DOWN IN THE SAME GENERAL AREA.
Probable cause
THE FAILURE OF THE ENGINE EXHAUST VALVE.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record LAX90LA015
- Event ID
- 20001213X29640
- Case number
- LAX90LA015
- 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: local date, investigation status. Values present in the bulk record are kept.
- The date is the local date; the NTSB stores the UTC date 1989-10-29.
- API snapshot SHA-256: 3d691226f82adf32c20e8fe6a2264066ce4b7e22d920f02fe20c48dba729ba1f; retrieved 2026-09-21T23:59:56.153Z.