HAMILTON, NC, USA
N2871H
PIPER PA-28-201T
THE PILOT REPORTED A VACUUM SYSTEM FAILURE AND A PITOT STATIC SYSTEM MALFUNCTION DURING AN INSTRUMENT FLIGHT UNDER INSTRUMENT WEATHER CONDITIONS, BUT HE ELECTED TO CONTINUE THE FLIGHT. THE FLIGHT TRACK AND ALTITUDE WERE ERRATIC. AFTER 28 MINUTES OF FLIGHT, THE PILOT REPORTED THAT HE WAS IN A DIVE. SUBSEQUENTLY, THE RIGHT OUTBOARD WING PANEL, RUDDER AND HORIZONTAL STABILATOR(S) SEPARATED IN FLIGHT. EXAMINATION OF THE AIRPLANE REVEALED THAT THE VACUUM PUMP DRIVE COUPLING SHEARED BECAUSE OF IMPROPER THREAD TREATMENT (SEALANT TAPE) USED DURING INSTALLATION. THE AIRPLANE WAS EQUIPPED WITH A STANDBY VACUUM SYSTEM, WHICH AT HIGHER ALTITUDES, REQUIRED THAT THE PILOT SPOOL THE SYSTEM (REDUCE POWER THEN ADVANCE THE THROTTLE) TO MAINTAIN VACUUM PRESSURE.
THE PILOT'S IMPROPER USE OF EQUIPMENT WHICH AFFECTED THE OPERATION OF THE STANDBY VACUUM PUMP, THE PILOT'S LOSS OF AIRCRAFT CONTROL AFTER EXPERIENCING SPATIAL DISORIENTATION, AND HIS EXCEEDING THE DESIGN STRESS LIMITS OF THE AIRCRAFT. FACTORS RELATED TO THE ACCIDENT WERE: THE MECHANIC'S IMPROPER USE OF THREAD COATING MATERIAL, THE PILOT'S OPERATION OF THE AIRCRAFT WITH A KNOWN MALFUNCTION OF THE PRIMARY VACUUM PUMP, AND THE ADVERSE WEATHER CONDITIONS.
Source: NTSB Aviation Accident Database
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