Summary:

Frequent breaking of piston rings in M/E.

Correction Action/ Lessons to be Learnt:
Improper liner calibration, usage of substandard ring (not – original from maker).
Incident:
After starting M/E, within few hours of operation, scavenge temperature of one cylinder found rising rapidly. Scavenge space inspection was carried out, found pieces of piston rings. Affected unit opened up after stopping the main engine, piston removed, and liner was calibrated. Found liner worn out badly beyond limits. After Calibration Company informed, liner replaced, piston rings renewed with original spare and the unit was commissioned.
Vessel went on off hire for one day.