# SDR 96ZZZX1523

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: November 20, 1995
- Submitted: March 26, 2000
- Operation: General aviation
- Aircraft: [N400BJ](https://openairdocs.org/aircraft/N400BJ), registered now
- Make and model: Cessna 421B
- Registry model: [Cessna 421B](https://openairdocs.org/model/cessna-421b) (OpenAirDocs)
- Aircraft serial: 421B0819
- Engine: Cont GTSIO520H
- System (JASC): [8520 · Reciprocating Engine Power Section](https://openairdocs.org/jasc/8520)
- Part: Crankcase Nut
- Part number: 634505
- Condition: Cracked
- Location: Engine
- Stage of operation: CR
- Nature of condition: K
- Precautionary procedure: O
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/96ZZZX1523

## Discrepancy

PILOT REPORTED OIL PRESSURE FLUCTUATION DURING FLIGHT, BUT NEVER OUT OF GREEN ARC.  UPON LANDING, NOTED ENGINE HAD HAD A MAJOR OIL LEAK.  UPON INVESTIGATION, FOUND ONE OF THE THROUGH-BOLT NUTS HAD CRACKED, THIS WAS LOCATED ON THE FWD LOWER PART OF THE CASE.  THE ENGINE HAD LOST ALMOST 6 QUARTS OF 0.1 ON A ONE-HOUR FLIGHT.  LOOKING AT NUT WITH A 10-POWER MAGNIFYING GLASS, NOTED A LOT OF MACHINING MARKS LEFT ON IT.

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