**2. Methodology**

The work followed the traditional problem-solving methodology, developed in seven main steps (as shown in **Figure 3**) based on the PDCA (plan-do-control-act) cycle. This method has been highlighted in the organizational environment as a management method for process improvement and problem-solving, being the basis of continuous improvement, and can be used in any type of organization, whether it is a private company, a nonprofit organization, or in a public sector. The PDCA is a method that manages the decision-making in order to improve an organization's activities, much explored in the pursuit of improved performance. This makes the PDCA very important and contributes significantly to the achievement of better results [7].

The PDCA in organizations obtains opposite results, with extensive and voluminous plans based on the procedures followed in step "P" of the cycle PDCA that determines where you want to go by imposing effective planning, achieving a way to the desired situation, in its implementation the practice of "D" bringing the uncertainty of carrying out an important activity, because through audits it is found a large number of activities outside your procedure, following step "C" identifying something that is not going as planned. Finally, step "A" is responsible for closing the PDCA cycle, so little practiced, but through convincing actions based on failures in the previous steps ensuring problems arising giving meaning to an improvement cycle continuous process of a given process [8].

The concept of the PDCA methodology does not consist only of implementation of strategic changes, but also organizes the successive improvements in circles, consisting of four phases as described in **Table 1** [9].

Problem-solving methodology seeks to objectively define and surround the problem analyzed, identify and mitigate the root causes of each type of failure mode and implement controls, so that there are no recurrences of the problems and that earnings are routinely maintained.

#### **Figure 3.**

*Problem-solving road map (seven steps).*


#### **Table 1.**

*PDCA cycle steps. Adapted from Costa [9].*

As a first step, the methodology provides for the definition of the focus areas of the work, since the biomass lines (four in total) contain nine screws and, through the work, the most critical position was highlighted.

Having chosen the focus area, possible problems related to the base condition of the equipment, maintenance, and lubrication routines, in addition to operating standards that, in some way, could be contributing to the problem observed were verified.

With the definition of the problem, the focus area and the guarantee of systemic maintenance and operating standards, the root causes of each failure mode that caused the stoppage of the biomass screw were investigated. Using the "5 Whys" quality tool, the reasons were broken down to the last level of knowledge, making it possible to define countermeasures to mitigate each failure mode. After the measures were implemented, the recurrence of problems was monitored and, if that happened, the analysis cycle was remade, with new countermeasures defined. Finally, the maintenance of the gains obtained was guaranteed through the systematization of controls.
