Aviation Accident Summaries

Aviation Accident Summary NYC82FNA20

MARTHA'S VINEYARD, MA, USA

Aircraft #1

N71MA

SMITH AEROSTAR 601

Analysis

DURING AN ILS WITH THE AUTOPILOT COUPLER ON, A HIGH SINK RATE DEVELOPED TOWARD THE END OF THE APPROACH. THE PILOT UNCOUPLED THE AUTOPILOT AND BEGAN A MISSED APPROACH, BUT THE AIRCRAFT HIT THE TOP OF A TREE. HE DIVERTED AND LANDED AT PROVIDENCE, RI WITHOUT FURTHER INCIDENT. AFTER LANDING, SUBSTANTIAL DAMAGE OF THE RIGHT FLAP AND RIGHT PROPELLER WAS FOUND. A BENCH CHECK OF THE BENDIX FCS-810 AUTOPILOT REVEALED THAT THE TRANSISTORS IN THE GLIDE SLOPE WASH-OUT CIRCUIT WERE FAULTY. THEY WERE INTERMITTENTLY APPLYING A POSITIVE VOLTAGE THAT RESULTED IN A FALSE PITCH GYRO SIGNAL AND A DOWNWARD HARDOVER.

 

Source: NTSB Aviation Accident Database

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