# NTSB LAX92LA225: Schempp-Hirth Ventus A/16.6, N8KS, Tucson, AZ, May 31, 1992

- Type: NTSB accident investigation
- Classification: Accident · Serious injuries · Limited investigation · Final report
- Date: May 31, 1992, 16:00 local (23:00 UTC)
- Place: Tucson, AZ
- Coordinates: 31.900272, -111.35997 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=31.9003&lon=-111.3600&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: Serious injuries
- Injuries: 1 serious
- Status: Completed, report September 14, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 27631
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX92LA225
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/27631/pdf
- Page: https://openairdocs.org/ntsb/LAX92LA225

## Probable cause

THE INFLIGHT DISCONNECTION OF THE RIGHT AILERON 'OTELLIER COUPLER FITTING DUE TO LUBRICANTS ON THE COUPLER SLIDE LOCK PLATE, AND THE FAILURE OF THE GLIDER MANUFACTURER TO INCLUDE APPROPRIATE PRECAUTIONARY INFORMATION IN THE MAINTENANCE AND/OR FLIGHT MANUAL. FACTORS IN THE ACCIDENT WERE: THE FAILURE OF THE GLIDER AND FITTING MANUFACTURERS TO MANDATE FAIL/SAFE DEVICES FOR THE COUPLER FITTING, AND THE DESIGN OF THE GLIDER REGARDING THE FACILITATION OF THE COUPLER CONNECTIONS DURING THE GLIDER ASSEMBLY PROCESS.

## Sequence of events

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

- Airframe/component/system failure/malfunction, cruise
  - flt control syst,aileron control cable/rod - disconnected (cause)
  - maintenance,lubrication - inadvertent, pilot in command
  - acft/equip,inadequate aircraft manuals, manufacturer (cause)
  - information unavailable, pilot in command (cause)
  - acft/equip,inadequate design, manufacturer (contributing factor)
  - acft/equip inadequate,visual restriction, manufacturer (contributing factor)
- Loss of control - in flight, cruise
  - aircraft control - not possible, pilot in command
- Miscellaneous/other, descent - uncontrolled

## Analysis

AFTER 4.2 HOURS OF FLIGHT WHILE CRUISING AT 8,000 FT, THE RIGHT AILERON CONTROL SYSTEM 'OTELLIER FITTING DISCONNECTED. THE PILOT SAID THAT THE AILERON TRAIL POSITION IN THE AIRSTREAM CAUSED THE GLIDER TO ENTER A SPIRAL DIVE TO THE RIGHT WHICH COULD NOT BE STOPPED BY LEFT AILERON OR RUDDER. THE PILOT BAILED OUT ABOUT 1,000 FT AGL. THE GLIDER WAS ASSEMBLED ON 5/30/92 IN ACCORDANCE WITH THE FLT & MAINT MANUAL. THE GLIDER WAS THEN FLOWN FOR 4.6 HRS & PARKED OVERNIGHT. THE PILOT SAID HE LUBED THE MALE BALL FITTING PRIOR TO ASSEMBLY AS INSTRUCTED IN THE MANUAL & CLEANED & LUBED THE SLIDE LOCK PLATE WITH WD-40. THE FITTING MANUFACTURERS SAFETY MAINT INFO (NOT AVAILABLE TO PILOTS) REQUIRES THE BALL & SOCKET FITTINGS TO BE LUBED AT EACH ASSEMLBY, BUT CAUTION AGAINST ALLOWING LUBRICANTS ON THE SLIDE LOCK PLATE BECAUSE THE SLIDE 'MAY LOOSE ITS NONREVERSIBILITY' & CAUSE THE FITTING TO DISCONNECT. THE GLIDER MAINT AND FLT MANUAL DOES NOT CAUTION AGAINST LUBRICANTS ON THE SLIDE LOCK PLATE.

## Aircraft

- Registration: [N8KS](https://openairdocs.org/deregistered/N8KS-1992-06-19), registration cancelled 1992-06-19, S/N 325 (OpenAirDocs)
- Reported make and model: SCHEMPP-HIRTH VENTUS A/16.6 (VENTUS A/1)
- Registry model: [Schempp-Hirth VENTUS A/16.6](https://openairdocs.org/model/schempp-hirth-ventus-a-16-6) (registry code 3802052) (OpenAirDocs)
- Category: Glider
- Serial number: 325
- Airframe hours: 895
- Engines: unknown
- Damage: Destroyed
- Flight: Personal, Part 91
- Operator: Roy S. Cundiff
- Registered owner: Roy S. Cundiff
- Airworthiness certificate: Special, Experimental (Special)
- Last inspection: Annual, June 14, 1991, 95 hours before
- Departed: NONE
- Destination: NONE

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 50; private; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; seat: center; flight hours: 3,063 total, 2,125 in this make and model, 3,017 as pilot in command, 53 in the last 90 days, 46 in the last 30 days, 9 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 320° at 5 knots
- Visibility: 50 statute miles
- Lowest ceiling: none
- Temperature: 84 °F

## 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 19920531017409A](https://openairdocs.org/incident/19920531017409A), May 31, 1992: Sphrth VENTUSA, Tucson, AZ, Destroyed. Right aileron became disconnected in flight. Uncontrolled spiral. Bailed out. Slide lock fitting lubed in error.

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.

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