NTSB Identification: LAX94FA028.
The docket is stored in the Docket Management System (DMS). Please contact Records Management Division
Accident occurred Wednesday, October 27, 1993 in SAN SIMON, AZ
Probable Cause Approval Date: 09/30/1994
Aircraft: PIPER PA-24-250, registration: XBHOM
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.

AT O634 MST, THE PILOT FILED A VFR FLIGHT PLAN & RECEIVED WEATHER INFO FOR A ROUTE FROM EL PASO TO TUCSON. HE WAS ADVIZED OF 2 PIREPS REGARDING SEVERE TURBULENCE IN THE TUCSON AREA & OF AN AIRMET CONCERNING TURBULENCE BELOW 12000 FT. THE PILOT'S TAKEOFF & DEPARTURE APPEARED NORMAL, THEN THERE WAS NO FURTHER COMMUNICATION WITH THE AIRPLANE. WHILE EN ROUTE, AN IN-FLIGHT BREAKUP OF THE AIRCRAFT OCCURRED, BUT THERE WERE NO KNOWN WITNESSES. THE RIGHT OUTBOARD WING PANEL WAS FOUND ABOUT 2/10 MILE FROM THE MAIN WRECKAGE WITH EVIDENCE THAT IT HAD FAILED IN POSITIVE (UPWARD) LOADING. THE OUTBOARD 2/3 OF THE LEFT HORIZONTAL STABILIZER HAD SEPARATED, BUT WAS NOT FOUND; THERE WAS EVIDENCE THAT IT HAD FAILED DOWNWARD. A PARK RANGER NOTED THE PRESENCE OF A 'BLACK . . . DOME SHAPED' CLOUD OVER MOUNTAINS ABOUT 5 MI FROM THE CRASH SITE. IT WAS CAPPED WITH ANOTHER SMALLER CLOUD AT A HIGHER ELEVATION. THE NATIONAL WEATHER SERVICE HAD NOT ISSUED AN ADVISORY FOR SEVERE TURBULENCE, ALTHOUGH INFO FOR SUCH DETERMINATION EXISTED BEFORE THE FLIGHT.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

THE PILOT'S IMPROPER PLANNING/DECISION, AND HIS ALLOWING THE AIRPLANE TO EXCEED ITS DESIGN STRESS LIMITS, WHICH RESULTED IN OVERLOAD FAILURE OF THE RIGHT OUTBOARD WIND SECTION AND LEFT HORIZONTAL STABILIZER. FACTORS RELATED TO THE ACCIDENT WERE: THE ADVERSE WEATHER CONDITIONS, AND AN INADEQUATE HAZARDOUS WEATHER ADVISORY CONCERNING THE SEVERE TURBULENCE.

Full narrative available

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