# NTSB LAX89LA273: Cessna 172N, N5961J, Seligman, AZ, August 13, 1989

- Type: NTSB accident investigation
- Classification: Accident · Minor injuries · Limited investigation · Final report
- Date: August 13, 1989, 11:11 local (18:11 UTC)
- Place: Seligman, AZ
- Coordinates: 35.129318, -112.990379 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=35.1293&lon=-112.9904&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: Minor injuries
- Injuries: 2 minor, 2 uninjured
- Status: Completed, report September 30, 1991
- Report: Approved by Office Director
- NTSB case key (mKey): 26476
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX89LA273
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/26476/pdf
- Page: https://openairdocs.org/ntsb/LAX89LA273

## Probable cause

A LOSS OF ENGINE POWER DUE TO A FAILURE OF THE NUMBER 3 CYLINDER EXHAUST VALVE ROCKER ARM PIVOT STUD, WHICH WAS IN TURN CAUSED BY A STUCK EXHAUST VALVE.

## Sequence of events

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

- Loss of engine power(partial) - mech failure/malf, cruise
  - engine assembly,valve,exhaust - jammed (cause)
  - engine assembly,valve,exhaust - failure,total (cause)
- Forced landing, landing - flare/touchdown
- On ground/water encounter with terrain/water, landing - roll
  - terrain condition - berm (cause)

## Analysis

THE PILOT REPORTED THAT WHILE IN CRUISE FLIGHT, A SEVERE VIBRATION BEGAN IN THE ENGINE WITH A CORRESPONDING REDUCTION IN ENGINE RPM TO ABOUT 1500. THE PILOT NOTED THAT ALL ATTEMPTS AT REMEDIAL ACTION MET WITH NO SUCCESS AND THE ENGINE WAS PRODUCING INSUFFICIENT POWER TO MAINTAIN FLIGHT. THE PILOT ATTEMPTED TO LAND ON AN INTERSTATE HIGHWAY BUT THERE WAS TOO MUCH VEHICLE TRAFFIC TO MAKE A SAFE LANDING. THE PILOT THEN LANDED IN A DIRT FIELD ADJACENT TO THE HIGHWAY, CONTACTED A LARGE BERM DURING THE LANDING ROLL OUT AND THE AIRCRAFT NOSED OVER ON ITS BACK. EXAMINATION OF THE ENGINE REVEALED HEAVY DEPOSITS ON THE INTAKE AND EXHAUST VALVES. THE EXHAUST VALVE FOR THE NUMBER 3 CYLINDER WAS IN THE CLOSED POSITION AND COULD NOT BE MOVED. DETAILED EXAMINATION OF THE NUMBER 3 CYLINDER REVEALED THAT THE ROCKER ARM PIVOT STUD FOR THE EXHAUST VALVE WAS BROKEN WITH SHEAR SIGNATURES EVIDENT.

## Aircraft

- Registration: [N5961J](https://openairdocs.org/deregistered/N5961J-2017-04-04), registration cancelled 2017-04-04, S/N 17273847 (OpenAirDocs)
- Reported make and model: CESSNA 172N
- Registry model: [Cessna 172N](https://openairdocs.org/model/cessna-172n) (registry code 2072434) (OpenAirDocs)
- Category: Airplane
- Serial number: 17273847
- Airframe hours: 6130
- Engines: LYCOMING O-320-H2AD 160 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Operator: North Air, Inc.
- Registered owner: Gerald J. Fitzgerald
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, June 26, 1989, 37 hours before
- Departed: PRC, PRESCOTT, AZ

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 24; flight instructor, commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; seat: left; flight hours: 768 total, 91 in this make and model, 551 as pilot in command, 3 in the last 90 days, 3 in the last 30 days, 1 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: calm
- Visibility: 40 statute miles
- Lowest ceiling: none
- Temperature: 70 °F

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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