# NTSB LAX91LA035: Cessna 210M, N9139M, Fallbrook, CA, November 20, 1990

- Type: NTSB accident investigation
- Classification: Accident · Serious injuries · Limited investigation · Final report
- Date: November 20, 1990, 12:00 local (20:00 UTC)
- Place: Fallbrook, CA
- Coordinates: 33.389221, -117.210517 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=33.3892&lon=-117.2105&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: Serious injuries
- Injuries: 1 serious
- Status: Completed, report December 30, 1992
- Report: Approved by Office Director
- NTSB case key (mKey): 27064
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX91LA035
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/27064/pdf
- Page: https://openairdocs.org/ntsb/LAX91LA035

## Probable cause

THE FAILURE OF THE NUMBER 5 CYLINDER PISTON CONNECTING ROD DUE TO BENDING AND SUBSEQUENT FATIGUE FRACTURE. CONTRIBUTING TO THE ACCIDENT WAS THE IMPROPER STARTING PROCEDURE ACCOMPLISHED BY AN UNIDENTIFIED PERSON WHICH RESULTED IN EXCESSIVE FUEL IN THE CYLINDER RESULTING IN A HYDRAULIC LOCK WITHIN THE NUMBER 5 CYLINDER.

## 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
  - engine assembly,connecting rod - bent (cause)
  - starting procedure - improper, unknown (contributing factor)
  - engine assembly,connecting rod - fractured (cause)
- Forced landing, descent - emergency
- In flight collision with object, descent - emergency
  - object - pole

## Analysis

A CESSNA 210M LOST ENG POWER AND COLLIDED WITH A POLE AFTER A FORCED LANDING ON A CITY STREET. THE ENGINE CRANKCASE WAS FRACTURED AND THE #5 PISTON CONNECTING ROD HAD SEPARATED FROM THE ENG AND WAS FOUND ALONG THE WRECKAGE PATH. EXAM OF THE NUMBER 5 CYLINDER WALL DISCLOSED EVIDENCE OF THE AREA BELOW THE NORMAL PISTON STROKE BEING SCRAPED BY THE PISTON RINGS. ACCORDING TO THE METALLURGIC REPORT, THE PISTON'S CONNECTING ROD FAILED DUE TO A FATIGUE CRACK. THE CONNECTING ROD WAS BENT SOME TIME AFTER INITIAL ENG OPERATION. THE BENDING THAT OCCURRED TO THE NO. 5 CONNECTING ROD IS   CHARACTERISTIC OF AN HYD LOCK CONDITION WHERE THE PISTON IS FORCED AGAINST INCOMPRESSIBLE FLUIDS BETWEEN THE PISTON AND CYLINDER HEAD. NO INDICATION OF METALLURGICAL DEFECT WAS OBSERVED IN THE CONNECTING ROD. HARDNESS READINGS ON THE     CONNECTING ROD, WHICH INDICATES THE STRENGTH, CONFORMED TO MATERIAL SPECIFICATIONS. THE MAINTENANCE RECORDS NOTE THAT A MAJOR OVERHAUL WAS ACCOMPLISHED 207.8 HOURS BEFORE THE ACCIDENT.

## Aircraft

- Registration: [N9139M](https://openairdocs.org/deregistered/N9139M-2009-09-15), registration cancelled 2009-09-15, S/N 21062064, built 1977 (OpenAirDocs)
- Reported make and model: CESSNA 210M
- Registry model: [Cessna 210M](https://openairdocs.org/model/cessna-210m) (registry code 2073450) (OpenAirDocs)
- Registry engine: [Continental IO-520 series](https://openairdocs.org/engine/continental-io-520-series) (registry code 17032, reciprocating) (OpenAirDocs)
- Category: Airplane
- Serial number: 62064
- Airframe hours: 1942
- Engines: CONTINENTAL IO-520L 300 horsepower reciprocating
- Damage: Destroyed
- Flight: Business, Part 91
- Operator: Self Enterprises
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, August 9, 1989, 208 hours before
- Destination: UNKNOWN

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 44; private; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 3, valid medical--no waivers/lim.; seat: left; flight hours: 500 total

## Weather

- Conditions: Visual (VMC), Day
- Lowest ceiling: none
- Temperature: -0 °F, dew point -0 °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 19901120051529A](https://openairdocs.org/incident/19901120051529A), Nov 20, 1990: Cessna 210M, Fallbrook, CA, Destroyed. Lost power hit pole city street. Broke connecting rod. Hydraulic cylinder lock due start procedure. Excessive fuel.

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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