# SDR 98ZZZX1335

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: March 4, 1998
- Submitted: March 26, 2000
- Operation: General aviation
- Aircraft: N60RR
- Make and model: Cessna 421C
- Registry model: [Cessna 421C](https://openairdocs.org/model/cessna-421c) (OpenAirDocs)
- Aircraft serial: 421C0885
- Engine: Cont GTSIO520L
- System (JASC): [8520 · Reciprocating Engine Power Section](https://openairdocs.org/jasc/8520)
- Part: Thru Bolt
- Part number: 6419311075
- Condition: Failed
- Location: Nr 6 Cyl Flange
- Part time: 679 hours
- Stage of operation: IN
- Nature of condition: O
- Precautionary procedure: K
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/98ZZZX1335

## Discrepancy

DURING 100-HOUR INSPECTION, FOUND THE NR 6 CYLINDER TOP FORWARD STUD/THRU-BOLT BROKEN AT THE CYLINDER BASE.  TCM TECH REP SAYS THAT THERE HAS BEEN A PROBLEM WITH THRU-BOLTS BREAKING EVEN BEFORE THEY LEAVE THE FACTORY.  HYDROGEN EMBRITTLEMENT IS THE CAUSE.  SUBMITTER DOESN'T KNOW WHY THIS ONE BROKE.

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