# NTSB LAX90LA015: Grumman AA-1A, N9330L, Borrego Springs, CA, October 29, 1989

- Type: NTSB accident investigation
- Classification: Accident · Minor injuries · Limited investigation · Final report
- Date: October 28, 1989, 17:30 local (Oct 29, 1989, 00:30 UTC)
- Place: Borrego Springs, CA
- Coordinates: 33.170883, -116.269485 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=33.1709&lon=-116.2695&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: Minor injuries
- Injuries: 1 minor
- Status: Completed, report July 22, 1992
- Report: Approved by Office Director
- NTSB case key (mKey): 26673
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX90LA015
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/26673/pdf
- Page: https://openairdocs.org/ntsb/LAX90LA015

## Probable cause

THE FAILURE OF THE ENGINE EXHAUST VALVE.

## Sequence of events

In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf).

- Loss of engine power(total) - mech failure/malf, cruise - normal
  - engine assembly,valve,exhaust - failure,total (cause)
- Forced landing, descent - emergency
- On ground/water encounter with terrain/water, landing - roll
  - terrain condition - berm
- Nose over, landing - roll

## Analysis

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.

## Aircraft

- Registration: [N9330L](https://openairdocs.org/deregistered/N9330L-2013-03-18), registration cancelled 2013-03-18, S/N AA1A-0030, built 1971 (OpenAirDocs)
- Reported make and model: GRUMMAN AA-1A
- Registry model: [American AA-1A](https://openairdocs.org/model/american-aa-1a) (registry code 0630710) (OpenAirDocs)
- Registry engine: [Lycoming 0-235 series](https://openairdocs.org/engine/lycoming-0-235-series) (registry code 41505, 4 cycle) (OpenAirDocs)
- Category: Airplane
- Serial number: AA1A-0030
- Airframe hours: 2093
- Engines: LYCOMING O-235-L2C 108 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Operator: John L. Lee, doing business as Best West Flyers, Inc.
- Last inspection: Annual, July 3, 1989, 43 hours before
- Departed: L08, BORREGO SPRINGS, CA
- Destination: MYF, SAN DIEGO, CA

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 23; private; airplane ratings: single-engine land; medical: class 2, valid medical--w/ waivers/lim; flight hours: 89 total, 29 in this make and model, 58 as pilot in command, 77 in the last 90 days, 33 in the last 30 days, 6 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Dusk
- Visibility: 20 statute miles
- Lowest ceiling: none
- Temperature: -0 °F, dew point -0 °F

## FAA reports on this event (1)

The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs).

- [Accident 19891029043699A](https://openairdocs.org/incident/19891029043699A), Oct 29, 1989: Gulstm AA1A, Borrego Springs, CA, Substantial damage. Lost power and flipped over on forced landing. Valve broke off migrated through engine.

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

---
OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.