Ergonomic evaluation of aircraft maintenance based on VACP model
Authors: Chen Xiao , Zhang Zhen , Song Xin , Xu Xiang , Niu Jianwei 
Published: April 2022

In recent years, aircraft has become one of the most important means of transportation for people to travel, playing a vital role in people's life. With the continuous growth of China's aircraft traffic and the continuous expansion of fleet size, higher requirements are put forward in the field of aircraft maintenance and design in order to ensure the safe operation of aircraft. However, the workload of civil aviation aircraft maintenance personnel is increasing and has not yet been paid enough attention. Due to limited resources such as the operator’s information processing capacity, memory and attention, unreasonable workflows and unbalanced workloads can lead to operator performance degradation and even errors when conducting heavy and time-critical tasks. Therefore, it is of great significance to study the workload of civil aviation maintenance personnel. At present, the main methods of workload assessment, such as questionnaire survey, secondary task evaluation and physiological index evaluation, provide great help for workload assessment. Whereas the questionnaire method is susceptible to the influence of expert experience, the secondary task evaluation method has higher requirements for experimental design and control, and the physiological index evaluation method has more complicated physiological signal acquisition procedures, long cycle and high experimental cost. The VACP model, a powerful cognitive tool, proposes that workload consists of Visual (V), Auditory (A), Cognitive (C), and Psychomotor (P). The VACP model can reflect the nature of workload more comprehensively. This paper designs a workload evaluation system based on VACP model. First, people set up the therblig's analysis function module. For any maintenance, the module can decompose the activity into a combination of maintenance therbligs, together with related attributes such as name, type and duration. The system determines whether there are uneconomical, unbalanced, and unreasonable phenomena in the action through the Gilbreths principle, and the rational adjustment of the operator's action flow, so as to achieve the improvement of the overall efficiency of the operator's maintenance work, and to make the operator's physical and mental pleasure to a certain extent promote. Second, we designed a workload evaluation module based on the VACP model. We evaluated the workload values of the four channels according to the maintenance video. The system will calculate the workload of the maintenance operator based on the VACP function, and output the calculation results as a line graph to the system interface. In addition, in order to verify the effectiveness of this function, this paper took civil aviation aircraft maintenance tasks as the research object and recruited a total of 6 male college students to participate the maintenance experiment. The experiment verifies the accuracy and validity of the system output. Experimental results show that the functional model of the system is accurate and effective. However, the function model of the system based on the VACP model ignores the time factor, because the length of the task will affect the operator workload. Therefore, the function model should consider the maintenance workload with the time variable in future. This system can be anticipated to be applied to aircraft maintenance workload assessment, and greatly improve maintenance efficiency, which has a great significance for the ergonomic status of the maintenance personnel.