# SDR 96ZZZX3442

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: February 12, 1996
- Submitted: March 26, 2000
- Operation: General aviation
- Aircraft: N4520S
- Make and model: Beech 58
- Registry model: [Beech 58](https://openairdocs.org/model/beech-58) (OpenAirDocs)
- Aircraft serial: TH660
- Engine: Cont IO520C
- System (JASC): [8520 · Reciprocating Engine Power Section](https://openairdocs.org/jasc/8520)
- Part: Crankcase
- Condition: Failed
- Location: Nr 1-2 Cylinders
- Part time: 1,086 hours
- Stage of operation: AP
- Nature of condition: O
- Precautionary procedure: O
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/96ZZZX3442

## Discrepancy

DIPSTICK DEPARTED AIRCRAFT ON FINAL.  MAINTENANCE UNCOWLED ENGINE TO PERFORM COMPRESSION TEST.  ENGINE CRANKCASE HAD ERUPTED BETWEEN NR 1 AND NR 2 CYLINDER.  BOTH MAGNETOS TORN FROM MOUNTING PADS NR 1 AND NR 2 CYLINDER ROD CAPS AND ROD BOLTS SHEARED FROM RODS AND 1 COUNTERWEIGHT DETACHED FROM CRANKSHAFT.  SUSPECT CAUSE:  COUNTERWEIGHT PIN FAILURE.  ENGINE MANUFACTURER NOTIFED AND REP TO EXAMINE ENGINE TEAR DOWN INSPECTION REQUESTED BY OWNER, OPERATOR, AND MAINTENANCE.

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