Human Errors in Helicopter Maintenance: overview of recommendations for improving safety
Authors: Bernard Fabien , Paquin Raphael , Dos-Santos Kévin 
Published: June 2023

The maintenance is defined as the second cause of aviation incidents or accidents. Indeed, 12% of all aviation accidents were due to human factors/ergonomics (HFE) issues during maintenance activity (Hobbs, 2000). However, regarding the aviation history, Human performance has been studied from the very beginning in the aviation field, especially regarding fixed wing accidents (Maurino et al., 1993; Wiener & Nagel, 1988). Initially, the reliability of machines was the primary concern, and many attempts were made to improve the technology of the devices (Maurino et al., 1993; Wiener & Nagel, 1988). During the following decades, HFE raised as a discipline to design the flight deck and to investigate the interaction between human (pilot) and machine, particularly, during the training phase of the pilot in a simulator (Wiener & Nagel, 1988; Horeman et al., 2015). Safety and comfort in the cockpit and the passenger cabin were also improved by considering HFE principles during the subsequent decades (Spenser, 2008). The consideration of Human Factors in maintenance is more recent. Integrating HFE in maintainability increases the quality of maintenance activities and reduces the rate of mistakes/errors (Gruber et al., 2015). The design engineers in the maintainability department interact and collaborate with other engineering departments (e.g., aerodynamic, hydraulic and electric integration, and architecture) and support disciplines including aircraft maintenance manual to consider maintenance & HF criteria during design phases. This interaction could raise HFE culture between them could effectively affect the future maintenance activity. However, aviation accidents are not the only problem that demonstrates the need to improve HFE for maintenance activities. The health and safety of maintenance operators is also a key contributor to maintenance errors (Hobbs, 2000). Various studies have already highlighted the fact that maintenance activities can cause health problems (musculoskeletal disorders, stress, and high mental workload) and workplace accidents (AFIM, 2004; European Agency for Safety and Health at Work, 2010). In a survey of 2,500 maintenance operators from various industries (automotive, train, and aeronautics), AFIM showed that 62% of respondents considered their occupation to be dangerous. Another study performed in Europe showed that 15%–20% of accidents at work occurred in the field of maintenance, suggesting that maintenance tasks are the most dangerous activities in an industry (European Agency for Safety and Health at Work, 2010).In order to reduce the risk of error, and also improve the work condition of maintenance operator, one of the solution is to better understand the current feedback of customer’s daily activity. Airbus Helicopters has launched a huge campaign of preventive Human Factors analysis. In this frame, the most sensitive maintenance tasks on existing helicopters have been studied to impact the design, procedure, maintenance tools and training. These maintenance tasks mainly concern sensitive mechanical system (Main Rotors, Main Rotor Drives, Tail Rotor, Tail Rotor Drives and Rotor Flight Control) regrouping lots of critical parts. In this article, we will first present a brief background of Human Factors in aviation maintainability. Then we will describe the methodologies and tools used to assess Human Factors dimensions during the observation of sensitive maintenance tasks. Additionally, we will introduce the main results and outcomes of all this analysis, all tasks and helicopters combined. We will provide some safety recommendations and improvement in the design & maintenance procedure for future development, mainly by highlighting six categories (Work at Height, Foreign Object Damages, Incorrect assembly, Number of Operators requested to perform the maintenance task, Damage prevention, Damage identification).