# SDR CA120620008

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: March 26, 2012
- Submitted: September 14, 2015
- Operation: General aviation
- Make and model: Cessna A185F
- Registry model: [Cessna A185F](https://openairdocs.org/model/cessna-a185f) (OpenAirDocs)
- Engine: Cont IO520*
- Propeller: Mcauly D2A34C58
- System (JASC): [8520 · Reciprocating Engine Power Section](https://openairdocs.org/jasc/8520)
- Part: Crankshaft
- Part number: CN631649F
- Condition: Failed
- Location: Engine
- Stage of operation: CR
- How discovered: O
- Nature of condition: Y
- Precautionary procedure: B, A
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/CA120620008

## Discrepancy

(CAN) ACFT ENG SN 282949-R CRANKCASE FAILURE, 7TH STUD CRANKCASE, CRANKCASE FRETTING ON NR 2 & 3 INTERMEDIATE BEARING SADDLE THRU-BOLT PADS.  WHEN THIS OCCURS, THE PINCH FIT IS LOST ON THE MAIN BEARINGS IN THESE POSITIONS & THEY BECOME LOOSE.  AS A RESULT, THE BEARING TENDS TO SHUFFLE BACK & FORTH WITH THE THRUST OF THE CRANKSHAFT FWD & THEN BACK.  IN THIS CASE, THE BEARING TANGS WERE WORN OFF DUE TO THIS MOVEMENT.  THE MAIN BEARING IN THE NR 2 POSITION STARTED TO COME APART, ALLOWING THE OTHER HALF OF THE BEARING TO MOVE & RIDE UP INTO THE CRANKSHAFT RADIUS CREATING A STRESS RISER.  THE CRANKSHAFT BROKE JUST IN THE FWD RADIUS BELOW NR 2 MAIN JOURNAL, RESULTING IN A CATASTROPHIC FAILURE OF THE ENG.

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