# NTSB NYC91LA102: Schweizer SGS-1-30, N3620D, Wurtsboro, NY, April 6, 1991

- Type: NTSB accident investigation
- Classification: Accident · Fatal · Limited investigation · Final report
- Date: April 6, 1991, 12:20 local (17:20 UTC)
- Place: Wurtsboro, NY
- Coordinates: 41.570232, -74.48069 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=41.5702&lon=-74.4807&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: Fatal
- Injuries: 1 fatal
- Status: Completed, report April 8, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 36900
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=NYC91LA102
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/36900/pdf
- Page: https://openairdocs.org/ntsb/NYC91LA102

## Probable cause

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.

## Sequence of events

In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf).

- Airframe/component/system failure/malfunction, descent
  - in-flight planning/decision - improper, pilot in command (contributing factor)
  - procedures/directives - not followed, pilot in command (contributing factor)
  - elevator trim - improper use of, pilot in command (cause)
  - elevator - improper use of, pilot in command (cause)
  - design stress limits of aircraft - exceeded, pilot in command (cause)
- In flight collision with terrain/water, descent - uncontrolled
  - object - tree(s)

## Analysis

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.

## Aircraft

- Registration: [N3620D](https://openairdocs.org/deregistered/N3620D-1992-12-28), registration cancelled 1992-12-28, S/N 20 (OpenAirDocs)
- Reported make and model: SCHWEIZER SGS-1-30
- Registry model: [Schweizer SGS 1-36](https://openairdocs.org/model/schweizer-sgs-1-36) (registry code 8050153) (OpenAirDocs)
- Category: Glider
- Serial number: 20
- Airframe hours: 1240
- Engines: unknown
- Damage: Destroyed
- Flight: Personal, Part 91
- Operator: Wurtsboro Flight Service, Inc.
- Registered owner: Wurtsboro Flight Service, Inc.
- Last inspection: 100 hour, February 20, 1991, 26 hours before

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 41; private; seat: center; toxicology performed; flight hours: 52 total, 5 in this make and model, 21 as pilot in command, 1 in the last 90 days, 1 in the last 30 days, 1 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 270° at 10 knots
- Visibility: 25 statute miles
- Lowest ceiling: none

## FAA reports on this event (1)

The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs).

- [Accident 19910406009239A](https://openairdocs.org/incident/19910406009239A), Apr 6, 1991: Scwzer SGS136, Wurtsboro, NY, Destroyed, 1 fatal. Pulled up abruptly from very high speed descent,both wings broke off from overload. No evidence mechanical failure.

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

---
OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.