# NTSB ANC92FA005: Piper PA-18, N3850Z, Montague Island, AK, October 16, 1991

- Type: NTSB accident investigation
- Classification: Accident · Minor injuries · Field investigation · Final report
- Date: October 15, 1991, 16:55 local (Oct 16, 1991, 00:55 UTC)
- Place: Montague Island, AK
- Coordinates: 60.789379, -145.609329 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=60.7894&lon=-145.6093&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: Minor injuries
- Injuries: 1 minor
- Status: Completed, report May 3, 1993
- Report: Approved by Office Director
- NTSB office: Alaska Regional Office
- NTSB case key (mKey): 5637
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC92FA005
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/5637/pdf
- Page: https://openairdocs.org/ntsb/ANC92FA005

## Probable cause

THE POWER LOSS DUE TO THE CRANKSHAFT FAILURE.  CONTRIBUTING TO THE ACCIDENT WAS IMPROPER MAINTENANCE DURING THE LAST ENGINE OVERHAUL.

## Analysis

DURING CRUISE FLIGHT, THE ENGINE SEIZED WITHOUT WARNING.  WITH NO SUITABLE LANDING AREA ON THE BEACH, THE PILOT DITCHED IN THE OCEAN AND SWAM ASHORE ABOUT 1/2 MILE AWAY.  AN INVESTIGATION REVEALED THAT THE CRANKSHAFT HAD BROKEN AT THE FORWARD CHEEK OF THE #3 MAIN BEARING.  A REDDISH SEALANT RESIDUE WAS FOUND AROUND THE MAIN BEARING THRU STUD HOLES OF THE CRANKCASE.  ACCORDING TO LYCOMING SERVICE INSTRUCTION #1125A, SEALANT SHOULD NOT HAVE BEEN APPLIED IN THIS AREA.

## 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,crankshaft - failure,total (cause)
  - maintenance,overhaul - improper, other maintenance personnel (contributing factor)
- Forced landing, descent - emergency
- Ditching, descent - emergency
  - terrain condition - none suitable
  - terrain condition - water

## Aircraft

- Registration: [N3850Z](https://openairdocs.org/deregistered/N3850Z-2013-04-17), registration cancelled 2013-04-17, S/N 18-7608, built 1961 (OpenAirDocs)
- Reported make and model: PIPER PA-18
- Registry model: [Piper PA-18-150](https://openairdocs.org/model/piper-pa-18-150) (registry code 7101828) (OpenAirDocs)
- Registry engine: [Lycoming 0-320 series](https://openairdocs.org/engine/lycoming-0-320-series) (registry code 41508, reciprocating) (OpenAirDocs)
- Category: Airplane
- Serial number: 18-7608
- Airframe hours: 1653
- Engines: LYCOMING O-320-B2B 160 horsepower reciprocating
- Damage: Substantial damage
- Flight: Business, Part 91
- Operator: Monnett, Charles W.
- Registered owner: Monnett, Charles W.
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, February 18, 1991, 63 hours before
- Departed: CDV, CORDOVA, AK
- Destination: CDV, CORDOVA, AK
- Flight plan: VFR

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 42; commercial; airplane ratings: single-engine land; medical: class 2, valid medical--no waivers/lim.; seat: front; flight hours: 1,000 total, 75 in this make and model, 950 as pilot in command, 100 in the last 90 days, 40 in the last 30 days, 4 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 120° at 2 knots
- Visibility: 50 statute miles
- Lowest ceiling: none
- Temperature: 39 °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 19911015046529A](https://openairdocs.org/incident/19911015046529A), Oct 15, 1991: Piper PA18150, Montague Island, AK, Substantial damage. Engine seized. Ditched in ocean. Crankshaft failure due oil starvation. When a bearing rotated. Improper sealing used

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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