It is performed to fix or correct any fault or breakdown in equipment or facilities during production time, therefore it is not planned.
It is carried out from the moment the fault occurs, where many times the tools and spare parts necessary for quick and efficient maintenance are not available.

• It is profitable and even convenient in equipment that does not intervene instantaneously or directly in production, where the implementation of another system would be less economical.
• If the equipment is ready, the intervention in the breakdown can be fast and the minimum downtime.
• An excessive infrastructure is not needed, a group of competent operators will be sufficient, therefore, the cost of labor will be minimal, the experience and expertise of the operators will be a higher priority, than the analysis or study capacity of the type of problem to occur.
• It directly affects production since it is carried out when there is a fault or failure in the equipment or production facilities.
• Due to the need to start up the equipment or facilities as soon as possible, it is often necessary to carry out low-quality, non-definitive repairs, which generate other breakdowns or require other subsequent maintenance.
• This creates a feeling or even a habit of working defectively, creating dissatisfaction and helplessness in the technicians and professionals who carry it out.
• It requires having staff without any kind of foresight, so you should have a non-priority planning in some other task, if you don't want to have idle staff.
• This is the most expensive maintenance since the necessary parts or spare parts have to be purchased at any cost (as long as the necessary budget is available).
• It works under pressure taking into account that part of the plant or the complete plant may be waiting for start-up.