# NTSB LAX91LA294: Cessna 140, N3160N, Montague, CA, July 7, 1991

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: July 7, 1991, 12:45 local (19:45 UTC)
- Place: Montague, CA
- Coordinates: 41.760421, -122.390159 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=41.7604&lon=-122.3902&mi=10
- Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 2 uninjured
- Status: Completed, report March 31, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 27275
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX91LA294
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/27275/pdf
- Page: https://openairdocs.org/ntsb/LAX91LA294

## Probable cause

THE FAILURE OF AN EXHAUST VALVE IN THE ENGINE.

## Sequence of events

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

- Loss of engine power, approach
  - engine assembly,valve,exhaust - failure,total (cause)
- Forced landing, descent - emergency
- On ground/water encounter with terrain/water, landing - roll
  - terrain condition - berm
- Nose over, landing - roll

## Analysis

DURING CRUISE FLIGHT THE PILOT HEARD A LOUD BANGING NOISE COMING FROM THE ENGINE COMPARTMENT. THE PILOT REPORTED BEING UNABLE TO MAINTAIN ALTITUDE, AND HE MADE A FORCED LANDING. DURING ROLLOUT THE AIRPLANE COLLIDED WITH A BERM AND NOSED OVER. AN EXAMINATION OF THE ENGINE REVEALED THE NUMBER ONE CYLINDER'S EXHAUST VALVE WAS BROKEN. THE VALVE HAD BEEN IN USE FOR AT LEAST 973 OPERATIONAL HOURS PRIOR TO THE ACCIDENT.

## Aircraft

- Registration: [N3160N](https://openairdocs.org/deregistered/N3160N-2012-09-27), registration cancelled 2012-09-27, S/N 13418, built 1947 (OpenAirDocs)
- Reported make and model: CESSNA 140
- Registry model: [Cessna 140](https://openairdocs.org/model/cessna-140) (registry code 2071602) (OpenAirDocs)
- Registry engine: [Continental C85 series](https://openairdocs.org/engine/continental-c85-series) (registry code 17008, reciprocating) (OpenAirDocs)
- Category: Airplane
- Serial number: 13418
- Airframe hours: 1668
- Engines: CONTINENTAL 85F 85 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Operator: Jack W. Potter
- Registered owner: Jack W. Potter
- Last inspection: Annual, March 11, 1991, 28 hours before
- Departed: 3S2, AURORA, OR
- Destination: AUN, AUBURN, CA

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 55; private; airplane ratings: single-engine land; medical: class 3, valid medical--w/ waivers/lim; flight hours: 275 total, 87 in this make and model, 201 as pilot in command, 59 in the last 90 days, 18 in the last 30 days, 3 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Visibility: 30 statute miles
- Lowest ceiling: none

## 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 19910707026239A](https://openairdocs.org/incident/19910707026239A), Jul 7, 1991: Cessna 140, Montague, CA, Substantial damage. Loud bang. Lost power. Nosed over on forced landing. NR1 cylinder exhaust valve broke.

## Other investigations on N3160N (1)

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.

- [NTSB WPR10CA106](https://openairdocs.org/ntsb/WPR10CA106), Jan 9, 2010: Cessna 140 (N3160N), Chico, CA, substantial damage. Probable cause: The pilot’s inadequate weather evaluation and failure to maintain clearance from trees while maneuvering in low visibility conditions.

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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