# NTSB DEN84LA052: Lake LA-4-200, N39451, Great Falls, MT, December 28, 1983

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: December 27, 1983, 22:10 local (Dec 28, 1983, 05:10 UTC)
- Place: Great Falls, MT
- Coordinates: 47.509723, -111.270706 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=47.5097&lon=-111.2707&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed
- Report: Approved by Office Director
- NTSB case key (mKey): 16308
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN84LA052
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/16308/pdf
- Page: https://openairdocs.org/ntsb/DEN84LA052

## 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, climb - to cruise
  - lubricating system,oil seal - leak (cause)
  - fluid,synthetic oil - lack of (cause)
- Forced landing, landing - flare/touchdown

## Analysis

THE ACFT WAS DAMAGED IN A FORCED LANDING ON A HIGHWAY AFTER THE ENGINE SEIZED. THE PLT SAID 'THE ENGINE MADE UNUSUAL SOUNDS OF AN ENGINE RUNNING BAD.' THEN IT LOST COMPRESSION AND SEIZED. HE MADE A FORCED LANDING ON A HIGHWAY AND DAMAGEDTHE HULL. EXAMINATION OF THE ACFT REVEALED A SITUATION WHERE THE MAIN OIL BREATHER FROZE PREVENTING OIL VAPOR PRESSURE FROM VENTING; CAUSING THE ENGINE SEALS TO FAIL AND THEREBY DEPLETNG THE OIL SUPPLY.

## Aircraft

- Registration: [N39451](https://openairdocs.org/deregistered/N39451-1989-08-31), registration cancelled 1989-08-31, S/N 541 (OpenAirDocs)
- Reported make and model: LAKE LA-4-200
- Registry model: [Lake LA-4-200](https://openairdocs.org/model/lake-la-4-200) (registry code 5110310) (OpenAirDocs)
- Category: Airplane
- Serial number: 541
- Airframe hours: 1075
- Engines: LYCOMING IO-360-A1B 180 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Registered owner: Wilfred R. Frost
- Airworthiness certificate: Standard, Normal
- Last inspection: 100 hour, June 15, 1983
- Departed: MSO, MISSOULA, MT
- Destination: MLS, MILES CITY, MT
- Airport: GTF, Great Falls

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 36; flight instructor, commercial; airplane ratings: multi-engine land, single-engine sea, single-engine land; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; seat: left; flight hours: 1,865 total, 8 in this make and model, 1,650 as pilot in command, 9 in the last 90 days, 7 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Night/dark
- Wind: 220° at 13 knots
- Visibility: 15 statute miles
- Temperature: -9 °F, dew point 16 °F
- Altimeter: 30.00 inHg
- Observed at: GTF

## 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 19831227069979A](https://openairdocs.org/incident/19831227069979A), Dec 27, 1983: Conaer LA4200, Great Falls, MT, Substantial damage. Crash occurred during emergency landing after engine quit when oil breather froze over.

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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