Excessive wear could cause the turbine to move backwards into a non-moving part of the engine, the earlier directive said, provoking an oil fire and an uncontained engine failure.

It usually fails because of it being in too shady a spot, having poor drainage beneath or simply being so small it receives excessive wear, which causes compaction.

The terms of a lease normally put a restriction on the number of miles driven, require regular maintenance and penalize for excessive wear.

These boilers were not common, owing to drawbacks with excessive wear in service.

In addition, a roller cam engine was added in 1987 to prevent excessive wear to the cam.