olemus
ootamatust vajadusest tulenev hooldus

näiteid
ISO 23815:
hooldus töövõimelise olekuni
pärast tõrget või defekti avastamist
=
maintenance carried out after occurrence of a failure, or detection of a fault, in order to restore a functional crane to a state in which it can perform a required function

https://www.lawinsider.com/dictionary/unplanned-maintenance

ülevaateid
https://www.fiixsoftware.com/maintenance-strategies/unplanned-maintenance/

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