Fire in diesel generator following tests

  • Safety Flash
  • Published on 24 July 2023
  • Generated on 12 February 2026
  • IMCA SF 18/23
  • 2 minute read

There was a small fire in the engine room on a vessel in port. 

What happened?

The incident occurred when a diesel generator was being maintained by a third-party maintenance team.

On completion of a change of alternator bearings, the generator was tested at idling speed, and no problem was found. But when the generator was tested at operational speed, after a few minutes fire came out of the non-drive end exciters.

The alarm was raised; the diesel generator was brought to an emergency stop and the fire was put out with an extinguisher.

The incident occurred when a diesel generator was being maintained by a third-party maintenance team. On completion of a change of alternator bearings, the generator was tested at idling speed, and no problem was found. But when the generator was tested at operational speed, after a few minutes fire came out of the non drive end exciters. The alarm was raised; the generator was brought to an emergency stop and the fire was put out with an extinguisher.

What went wrong?

  • There was a misalignment of the internal cover of the non-drive end bearing.

  • This misalignment caused friction against the shaft and subsequent sparking.

  • The root cause was considered to be insufficient supervision of the third-party personnel conducting the maintenance.

Lessons learnt

  • Whilst there was only a burnt alternator in this case, the potential was for the fire to have spread throughout the engine room.

  • Ensure full and thorough supervision of the personnel of third-party contractors.

  • Check carefully the status and readiness of any equipment after maintenance and test – in this case, it was as well that they tested it at operational speed rather than only when idling.

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