NTSB Identification: NYC91LA102.
The docket is stored on NTSB microfiche number 45377.
Accident occurred Saturday, April 06, 1991 in WURTSBORO, NY
Probable Cause Approval Date: 04/08/1993
Aircraft: SCHWEIZER SGS-1-30, registration: N3620D
Injuries: 1 Fatal.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

THE GLIDER WAS OBSERVED IN A STEEP NOSE DOWN PITCH ATTITUDE. JUST ABOVE THE TERRAIN, THE NOSE PITCHED UP AND THE LEFT WING FAILED AT THE WING ROOT. THE GLIDER STRUCK TREES, DESCENDING TO THE GROUND. POST CRASH EXAMINATION SHOWED THE WING HAD FAILED IN OVERLOAD. ACCORDING TO THE MANUFACTURER, THE WING HAD AN ULTIMATE FAILURE LOAD OF 9.72G. EXAMINATION OF THE GLIDER SHOWED TAPE ON THE TRIM DISCONNECT SYSTEM AND CONTROL STICK. THIS IS A TECHNIQUE USED BY COMPETITION PILOTS TO REDUCE THE CONTROL FORCES. THERE IS A FLIGHT MANUAL LIMITATION AGAINST OPERATING WITH SPEEDS IN EXCESS OF 108 MPH WITH THE TRIM DISCONNECTED. FLIGHT TESTING BY THE MANUFACTURER SHOWED THE GLIDER HAD 'NEAR TO NEUTRAL STABILITY' WITH THE TRIM DISCONNECTED.

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

AN INFLIGHT FAILURE OF THE LEFT WING SPAR DUE TO OVERLOAD FROM PILOT INDUCED CONTROL INPUTS, WHILE RECOVERING FROM A DIVE. FACTORS RELATED TO THE ACCIDENT WERE, THE PILOT'S DECISION TO FLY WITH THE TRIM SYSTEM DISCONNECTED AND LACK OF RECENT EXPERIENCE IN MAKE AND MODEL OF GLIDER.

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