# NTSB LAX91LA255: Cessna 172N, N6230D, Thermal, CA, June 8, 1991

- Type: NTSB accident investigation
- Classification: Accident · Minor injuries · Limited investigation · Final report
- Date: June 8, 1991, 16:55 local (23:55 UTC)
- Place: Thermal, CA
- Coordinates: 33.479255, -116.100685 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=33.4793&lon=-116.1007&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 March 31, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 27241
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX91LA255
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/27241/pdf
- Page: https://openairdocs.org/ntsb/LAX91LA255

## Probable cause

THE PARTIAL FAILURE OF THE ENGINE/POWERPLANT FROM A WORN INTAKE VALVE AND THE FAILURE OF COMPANY/OPERATOR MANAGEMENT TO PERFORM AN OVERHAUL ON THE ENGINE WITHIN THE TIME FRAME RECOMMENDED BY THE ENGINE MANUFACTURER.

## 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
  - maintenance,overhaul - not performed, company/operator management (contributing factor)
  - engine assembly,valve,intake - worn (cause)
  - powerplant - failure,partial
- Forced landing, descent - emergency
- On ground/water encounter with terrain/water, landing - roll
  - terrain condition - dirt bank/rising embankment

## Analysis

A CESSNA 172N NOSED OVER IN SOFT SOIL DURING LANDING ROLL AFTER A FORCED LANDING.  THE PILOT INDICATED THAT THE ENGINE WAS RUNNING ROUGH AND LOSING POWER.  THE PILOT LANDED THE AIRPLANE ON AN AIRPORT, BUT WAS UNABLE TO MANEUVER THE AIRPLANE TO A RUNWAY.  THE AIRPLANE DECELERATED TO ABOUT 20 MPH DURING THE GROUND ROLL ON DIRT.  THE AIRPLANE NOSED OVER AFTER THE NOSE GEAR STRUCK A 15 TO 18 INCH HIGH DIRT BANK.  THE ENGINE WAS EXAMINED BY AN A&P MECHANIC.  THE A&P FOUND THE NUMBER THREE CYLINDER INTAKE VALVE WAS 'TULIPED.'  ACCORDING TO THE AIRPLANE'S MAINTENANCE RECORDS, THE ENGINE HAD ACCRUED 2,850 HOURS OF OPERATION WITHOUT OVERHAUL.  FORTY FOUR HOURS OF OPERATION BEFORE THE ACCIDENT, THE ENGINE'S CYLINDER COMPRESSION CHECKED 'OK' DURING A LEAK TEST.  THE ENGINE MANUFACTURER RECOMMENDED TIME BETWEEN OVERHAULS IS 1,500 HOURS.  DURING OVERHAUL THE VALVES ARE REMOVED AND VISUALLY CHECKED FOR WEAR.

## Aircraft

- Registration: [N6230D](https://openairdocs.org/aircraft/N6230D), registered now, S/N 17272648, built 1979 (OpenAirDocs)
- Reported make and model: CESSNA 172N
- Registry model: [Cessna 172N](https://openairdocs.org/model/cessna-172n) (registry code 2072434) (OpenAirDocs)
- Registry engine: [Lycoming 0-320 series](https://openairdocs.org/engine/lycoming-0-320-series) (registry code 41508, reciprocating) (OpenAirDocs)
- Category: Airplane
- Serial number: 17272648
- Airframe hours: 4949
- Engines: LYCOMING O-320 H2AD 160 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Operator: Consair Flying Club
- Registered owner: Sanders, William
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, April 9, 1991, 125 hours before
- Departed: L77, CHIRACO SUMMIT, CA
- Airport: TRM, Thermal, runway 3, 4,993 × 100 ft, dirt

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 30; private; airplane ratings: single-engine land; medical: class 1, valid medical--no waivers/lim.; seat: left; flight hours: 90 total, 8 in this make and model, 9 as pilot in command, 9 in the last 90 days, 2 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 190° at 9 knots
- Visibility: 25 statute miles
- Lowest ceiling: none
- Temperature: 100 °F, dew point 27 °F
- Altimeter: 29.00 inHg
- Observed at: TRM, 1 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 19910608020539A](https://openairdocs.org/incident/19910608020539A), Jun 8, 1991: Cessna 172N, Thermal, CA, Substantial damage. Rough engine and losing power undershot runway by changing runways close in. Worn valves. Engine 85HRS over tbo.

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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