NTSB Identification: NYC82FNA20
14 CFR Part 91: General Aviation
Accident occurred Friday, June 18, 1982 in MARTHA'S VINEYARD, MA
Probable Cause Approval Date: 06/18/1983
Aircraft: SMITH AEROSTAR 601, registration: N71MA
Injuries: 1 Uninjured.

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.

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.

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

PROPER ALTITUDE..NOT MAINTAINED..PILOT IN COMMAND


Contributing Factors

LIGHT CONDITION..DARK NIGHT


Contributing Factors

WEATHER CONDITION..LOW CEILING


Contributing Factors

WEATHER CONDITION..FOG


Contributing Factors

AUTOPILOT/FLIGHT DIRECTOR..ERRATIC



Contributing Factors

OBJECT..TREE(S)

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