# NTSB SEA91LA006: Mooney M20F, N9732M, Casper, WY, October 13, 1990

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: October 13, 1990, 11:10 local (17:10 UTC)
- Place: Casper, WY
- Coordinates: 43.170211, -107.319839 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=43.1702&lon=-107.3198&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 3 uninjured
- Status: Completed, report December 14, 1992
- Report: Approved by Office Director
- NTSB case key (mKey): 41353
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA91LA006
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/41353/pdf
- Page: https://openairdocs.org/ntsb/SEA91LA006

## Probable cause

THE LOSS OF ENGINE POWER DUE TO FATIGUE FRACTURE OF THE NUMBER 2 CYLINDER CONNECTING ROD. FACTORS RELATED TO THE ACCIDENT WERE: ROUGH AND UNEVEN TERRAIN AT THE ACCIDENT SITE AND THE LACK OF SUITABLE TERRAIN FOR FORCED LANDING.

## Sequence of events

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

- Loss of engine power(total) - mech failure/malf, cruise - normal
  - engine assembly,connecting rod - fractured (cause)
- Forced landing, descent - emergency
- In flight collision with terrain/water, landing - roll
  - terrain condition - rough/uneven (contributing factor)
  - terrain condition - none suitable (contributing factor)

## Analysis

THE PILOT MADE A FORCED LANDING AFTER THE ENGINE FAILED. INVESTIGATION REVEALED THE NUMBER 2 CYLINDER CONNECTING ROD LOWER YOKE WAS FRACTURED. METALLURGICAL EXAMINATION OF THE ROD REVEALED ROTATIONAL POLISHING AND GALLED SPOTS ON THE INSIDE YOKE SURFACES AND A FATIGUE FRACTURE OF THE YOKE THAT ORIGINATED AT THE INSIDE SURFACE.

## Aircraft

- Registration: [N9732M](https://openairdocs.org/deregistered/N9732M-1992-01-15), registration cancelled 1992-01-15, S/N 670292 (OpenAirDocs)
- Reported make and model: MOONEY M20F
- Registry model: [Mooney M20F](https://openairdocs.org/model/mooney-m20f) (registry code 5870214) (OpenAirDocs)
- Category: Airplane
- Serial number: 670292
- Airframe hours: 4388
- Engines: LYCOMING IO-360 200 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Operator: Glenn A Watts
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, October 12, 1989, 213 hours before
- Departed: 4AC, ALBUQUERQUE, NM
- Destination: CPR, CASPER, WY

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 51; commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 2, valid medical--w/ waivers/lim; seat: left; flight hours: 2,900 total, 650 in this make and model, 2,800 as pilot in command, 90 in the last 90 days, 50 in the last 30 days, 4 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 310° at 20 knots, gusting 26
- Visibility: 50 statute miles
- Lowest ceiling: 25,000 ft broken
- Temperature: 54 °F
- Altimeter: 29.00 inHg
- Observed at: CPR, 30 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 19901013045099A](https://openairdocs.org/incident/19901013045099A), Oct 13, 1990: Mooney M20F, Casper, WY, Substantial damage. Loud bang. Oil on windshield. Forced down rough terrain. Connecting rod broke engine case.

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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