NTSB Identification: LAX90LA015.
The docket is stored on NTSB microfiche number 42168.
Accident occurred Saturday, October 28, 1989 in BORREGO SPRINGS, CA
Probable Cause Approval Date: 07/22/1992
Aircraft: GRUMMAN AA-1A, registration: N9330L
Injuries: 1 Minor.
NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
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.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: THE FAILURE OF THE ENGINE EXHAUST VALVE.
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