# NTSB DEN90FA017: Cessna 172RG, N4825V, Laramie, WY, November 1, 1989

- Type: NTSB accident investigation
- Classification: Accident · Fatal · Field investigation · Final report
- Date: October 31, 1989, 17:32 local (Nov 1, 1989, 00:32 UTC)
- Place: Laramie, WY
- Coordinates: 41.309478, -105.579521 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=41.3095&lon=-105.5795&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: Fatal
- Injuries: 1 fatal
- Status: Completed, report June 26, 1992
- Report: Approved by Office Director
- NTSB case key (mKey): 17807
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN90FA017
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/17807/pdf
- Page: https://openairdocs.org/ntsb/DEN90FA017

## Probable cause

THE LOSS OF CONTROL OF THE AIRPLANE IN INSTRUMENT METEOROLOGICAL CONDITIONS AFTER THE PILOT BECAME SPATIALLY DISORIENTED. CONTRIBUTING TO THE ACCIDENT WAS THE FAILURE OF THE VACUUM SYSTEM WHICH RENDERED THE VACUUM/GYRO INSTRUMENTS INOPERATIVE. ALSO CONTRIBUTING TO THIS FAILURE WAS THE IMPROPER INSTALLATION OF THE VACUUM PUMP BY UNKNOWN PERSON(S).

## Sequence of events

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

- In flight encounter with weather, cruise - normal
  - preflight briefing service - disregarded, pilot in command
  - operation with known deficiencies in equipment - performed, pilot in command
  - vfr flight into imc - performed, pilot in command (contributing factor)
  - weather condition - low ceiling
  - weather condition - below approach/landing minimums
- Loss of control - in flight, cruise - normal
  - aircraft control - not maintained, pilot in command (cause)
  - spatial disorientation, pilot in command (cause)
- In flight collision with terrain/water, descent - uncontrolled

## Analysis

THE PLT RECEIVED A WEATHER BRIEFING FOR A VFR FLT. THE BRIEFING INDICATED IFR WEATHER ALONG THE INTENDED ROUTE OF FLIGHT. THE PLT STATED HE WAS CONDUCTING THE FLT VFR BECAUSE HE 'DID NOT TRUST HIS INSTRUMENTS.' APPROXIMATELY ONE HOUR AFTER DEPARTURE FROM LARAMIE, WY, THE PLT REQUESTED THE LARAMIE WEATHER IN AN ATTEMPT TO RETURN. THE PLT RADIOED HE LOST HIS GYROS AND DECLARED AN EMERGENCY. THE FSS RECEIVED A SPECIAL VFR CLEARANCE DUE TO BELOW VFR MINIMUM WEATHER, BUT WAS UNABLE TO ISSUE IT DUE TO LOST RADIO COMMUNICATIONS. POST-ACCIDENT INVESTIGATION REVEALED THE VACUUM PUMP HAD BEEN INSTALLED WITHOUT THE SHEAR SHAFT COUPLING. THE AIRFRAME AND ENGINE LOGBOOKS DID NOT IDENTIFY PREVIOUS WORK PERFORMED OR PERSON(S) WHO MAY HAVE WORKED ON THE PUMP.

## Aircraft

- Registration: [N4825V](https://openairdocs.org/deregistered/N4825V-1992-03-11), registration cancelled 1992-03-11, S/N 172RG0392 (OpenAirDocs)
- Reported make and model: CESSNA 172RG
- Registry model: [Cessna 172RG](https://openairdocs.org/model/cessna-172rg) (registry code 2072438) (OpenAirDocs)
- Category: Airplane
- Serial number: 172RG00392
- Engines: LYCOMING O-360-F1A6 180 horsepower reciprocating
- Damage: Destroyed
- Flight: Personal, Part 91
- Registered owner: Travis Air Patrol Company
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, December 9, 1988
- Departed: LAR
- Destination: RWL, RAWLINS, WY
- Airport: LAR, General Brees Field

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 58; flight instructor, commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 2, valid medical--w/ waivers/lim; seat: left; toxicology performed; flight hours: 14,350 total

## Weather

- Conditions: Instrument (IMC), Dusk
- Wind: 50° at 10 knots
- Lowest ceiling: 200 ft
- Temperature: 23 °F, dew point 21 °F
- Altimeter: 30.00 inHg
- Observed at: LAR, 7 nm away

## 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 19891031044149A](https://openairdocs.org/incident/19891031044149A), Oct 31, 1989: Cessna 172RG, Laramie, WY, Destroyed, 1 fatal. Lost control in near zero weather and spiraled in. Lost gyros due worn splines on vacumm drive.

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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