Maintenance of mechanized felling heads exposes workers to serious and even fatal accidents that result in expenditures that greatly exceed the average. This study follows a preliminary study that indicated to the forestry industry’s joint sector-based prevention committee the need for making these maintenance interventions safe. The researchers will analyze these operations in order to modify the adjustment of felling heads so that they can be made safer, by taking into account production-related constraints. The new actuator adjustment procedure for the heads of these machines will be integrated into forestry worker training. With this knowledge, other mobile equipment requiring maintenance interventions under difficult conditions can be made safe.