NTSB Identification: LAX94FA278.
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Accident occurred Monday, November 29, 1993 in JUNE LAKE, CA
Probable Cause Approval Date: 02/14/1996
Aircraft: MOONEY M20K, registration: N5788U
Injuries: 2 Fatal.
NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.
THE PILOT DEPARTED ON A 329 NAUTICAL MILE CROSS-COUNTRY FLIGHT OVER MOUNTAINS AND DID NOT FILE A FLIGHT PLAN. ABOUT 88 MILES FROM THE DEPARTURE POINT, THE AIRPLANE CRASHED, BUT WAS MISSING FOR ABOUT EIGHT MONTHS. IT WAS FOUND AT ABOUT THE 12,200 FOOT LEVEL OF A MOUNTAIN, ABOUT 2 MILES WEST OF THE DIRECT COURSE LINE FROM THE DEPARTURE POINT TO THE DESTINATION. AN INVESTIGATION REVEALED EVIDENCE OF AN IN-FLIGHT BREAKUP. WRECKAGE DEBRIS WAS FOUND OVER A 1,500 FOOT AREA. THE EMPENNAGE HAD SEPARATED FROM THE FUSELAGE, BUT WAS NOT FOUND, EXCEPT THE RUDDER AND ELEVATOR COUNTERWEIGHTS WERE FOUND IN DEBRIS NORTH OF THE FUSELAGE. THE AIRPLANE WAS EQUIPPED WITH AN AREA NAVIGATION SYSTEM, LORAN-C, AND A PORTABLE GPS. THE AUTOPILOT WAS FOUND ENGAGED. EXAMINATION OF THE WRECKAGE REVEAL THAT A PITCH TRIM SPRING IN THE AUTOPILOT PITCH SERVO HAD FAILED DUE TO FATIGUE. FURTHER EXAMINATION REVEALED THE AVIONICS IN THE AIRPLANE BELONGED TO AN AIRPLANE THAT HAD BEEN REPORTED STOLEN. THERE WERE NO RECORDS FOUND OF ANY INSPECTIONS OR MAINTENANCE BEING PERFORMED ON THE ACCIDENT AIRPLANE.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: THE PILOT ALLOWED THE AIRPLANE TO EXCEED ITS DESIGN LIMITS (AIRSPEED AND/OR STRESS LIMITS) AFTER INADVERTENTLY ENTERING A DESCENT. FACTORS RELATING TO THE ACCIDENT WERE: DARKNESS (NIGHT OR LATE DUSK), THE PILOT'S FAILURE TO ASSURE ADEQUATE MAINTENANCE/INSPECTION OF THE AIRPLANE, AND FATIGUE FAILURE OF A PITCH TRIM SPRING IN THE AUTOPILOT PITCH SERVO. Full narrative available
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