Halliday & Matthiessen (1999: 268-9):
This perturbation of the dominant pattern has the effect of making a participant more abstract. In the engine failed, the engine is set up as a thing. In engine failure, it is as it were deconstructed into a mere characteristic of some other 'thing', a way of classifying failure into its various contrasting kinds, such as crop failure, power failure and heart failure. The engine has lost its identity — it has no Deictic (note that it cannot be individuated any longer — only the failure can: this engine failure, the earlier engine failure, any future engine failures, etc.); and it has exchanged 'thingness' with an ephemeral process, that of failing. But it is still within the compass of a participant in the figure; grammatically, it is within the nominal group.