Making maintenance safer02 November 2023

 European Union Aviation Safety Agency Airbus

According to the European Union Aviation Safety Agency, 6% of helicopter accidents between 2007 and 2015 were caused by error in maintenance operations (excluding military helicopters). As a result, Airbus Helicopters has carried out an extensive human factors preventive analysis campaign

The human factors preventive analysis campaign was an extensive job involving hundreds of maintenance tasks. It began in 2018 starting with the H225, and was subsequently extended to the H175 and then H160 and H145 models.

It is based on human factors, the study of how people work around machinery. According to the International Civil Aviation Organisation (ICAO), ‘human factors encompass knowledge from a range of scientific disciplines that supports human performance through the design and evaluation of equipment, environments and work to improve system performance’.

Here, Raphaël Paquin, Airbus maintainability engineer and Fabien Bernard, Airbus human factors expert and researcher at the University of Bourgogne Franche-Comté, answer questions about the research programme and their findings.

Q: Please would you give an overview of recommended maintenance of helicopters. How frequently are they serviced, and what does servicing involve?

Raphaël Paquin and Fabien Bernard (RP&FB): “Helicopter maintenance occurs at three different levels. At the lowest operational level, daily checks and cleaning tasks require limited skill and tools. Beyond that are inspections, periodic checks, adjustments and replacement of small parts. Such work does require some special tools and dedicated training. At the highest level is work on major components, such as the transmission/gearbox, which requires special skills and is carried out by the OEM.

“At Airbus Helicopters, helicopter maintenance is divided into two main categories: scheduled and unscheduled maintenance. Each helicopter type has a different maintenance policy, which corresponds to market use and leads to various intervals for scheduled maintenance. For example, on the H145 (a twin-engine helicopter for emergency response/safety and rescue), intermediate inspection is 400FH (flight hours) and periodic inspection occurs at 1,000FH, or three years.”

The first phase consists of identifying the important or critical parts that could have serious consequences if they were defective.

Q: What were these parts?

RP&FB: “‘Important parts’ and ‘critical parts’ are those for which failure could have a direct impact on helicopter flight safety. These two categories are used for design and manufacture in accordance with the criticality of their function. They do not reflect the risk of maintenance error.

“We have developed a method that allows us to identify the most critical tasks to human factors based on those categories and, thanks to a zonal analysis, we can complete the list with the surrounding parts that could endanger safety if an error occurs. Thanks to the detailed analysis, we improve the maintenance of these parts to help maintenance operators to perform the job efficiently, reducing human errors considerably. We also try to preserve the health and safety of the operator.

“Depending on the helicopter type, we have identified around 200 of the most sensitive tasks that should be studied in detail through human hazard analysis to identify and mitigate human error risks.”

Airbus says that, for each associated maintenance task, maintenance operators, both at Airbus and at our customers’ sites, are asked to assess human error risk on the basis of six criteria: frequency, accessibility, resources, documentation, tools and susceptibility. If the task is identified as sensitive, it must be studied in detail.

Q: What was the scope of each of the criteria?

RP&FB: “Here is more information about the criteria:

  • Frequency of the task. This covers the risk of complacency for daily tasks and, at the other extreme, the risk of forgetting or lack of experience for rare tasks.
  • Access constraints. This covers lack of visual or physical access, bad posture, risk of injury / fall, heavy parts, high physical demand and long tasks.
  • Resources required/length of time needed for a task. This includes the number of engineers needed to perform maintenance tasks or the amount of time it takes, the risk of shift-change for long tasks and the risks posed by the need for communication for tasks requiring two or more operators.
  • Documentation. This covers content, clarity, illustration and media type, access to the procedure and navigation, links to other referenced procedure and pass/fail criteria
  • Need for specific tools. This covers dealing with complex tools, the risk of damaging either the tool or the helicopter during installation or use, the various type of existing tools, and so on
  • Susceptibility to damage. This covers any damage which the critical component could sustain due to any maintenance activities on this component, this system or an adjacent system or component, on- or off-aircraft. This is a free text field to allow an explanation of the issues identified.

  • “These criteria were defined through an international standard on human hazard analysis, published in 2019, with HeliOffshore, an association of oil and gas helicopter operators, and other helicopter OEMs. In a workshop setting, end-user maintenance technicians shared field experience. That information was used to pre-assess the sensitivity of various processes to human factors.

    “The HHA operator workshop allows us to prioritise the tasks that should be studied in detail. All tasks having a criteria rating greater than two (out of maximum score of five) are in this priority list. This helps Airbus to plan and organise the next step, the HHA detailed analysis, which requires specific resources (a human factors specialist and maintenance technicians) and means, such as tooling and documentation. In phase one, no recommendations are proposed, but this work lays the groundwork for detailed analysis.”

    According to Airbus, phase two takes place on board the helicopter. An operator carries out a maintenance task employing the procedure and the resources set out in the documentation in place. In each stage of the operation, the team responsible for analysing maintenance operations assesses the operator’s physical and workload constraints, as well as mental workload using international human factors criteria and standards.

    The assessment of each maintenance task requires approximately 30 worker hours, including four hours on the helicopter. Based on objective criteria the detailed analysis enables the company to set up new safety barriers. That can involve modifications in terms of procedures, documentation, tools and sometimes even the design.

    Q: What were the outcomes of this work?

    RP&FB: “In terms of impact, human factors assessment allows us to understand precisely the risk and provide a clear recommendation impacting the helicopter architecture, maintenance tools, documentation and/or to make our internal training more robust.

    “Feeding back the results of this into maintenance procedures involves adding more detailed information, such as pictures from operator point of view, proposing breaks when the task is judged as too long and recommending independent inspections. We have also clarified the standard practices manual.

    “In addition to our work, Airbus has also set up industrial and research partnerships. And to better integrate human factors in the entire process, dedicated methodology and tools are deployed in the design office to help the non-human factors specialists to take into account human factors requirements.”

    Q: How has Airbus set up teams to analyse maintenance operations?

    RP&FB: “In addition to ourselves, all maintainability specialists in the department – some 10 engineers with a mechanical engineering background completed with internal training on human factors principles and methodology – conduct regular observations under expert control. There four assessors: two experts in human factors, one subcontractor and one PhD candidate.”

    In parallel, the maintainability department of Airbus Helicopters’ design office is engaged in a wide research programme to improve the process. This includes the use of simulation tools like virtual reality and augmented reality to make human factors analyses more reliable during the design development.

    Q: What other research is under way?

    RP&FB: “There are now three main areas of research: to develop the human factors skills through all design stakeholders; to better use simulation tools (VR, XR…) to anticipate and assess human factors in early design stage; and to better understand the real constraints faced by maintenance operators, whether physiological, cognitive or organisational, and how to translate the real life to the design requirements.

    “Other PhD research is also conducted within Airbus Helicopters’ techData department to improve the usability of maintenance documentation for the final customer’s maintenance technicians, as well as research into authoring skills to ensure that documentation will not generate doubt or error.

    “As regards virtual tools, a key priority is the representativeness of the digital simulation. Clearly, we cannot simulate all maintenance tasks, and some tasks are only simulated on a physical mock-up. However, digital simulation technologies are growing very quickly and we can now add some tangible interface to reduce the gap between the real and virtual world.”

    Q: What can organisations responsible for maintenance and operations of other types of equipment learn from this project?

    RP&FB: “The human hazards analysis methodology is based on international standards, criteria and assessment tools, so its principles could be applied to any other heavy industry. But the detailed method and process should be tailored depending on its specifics, taxonomy, worker situation and design principles, as any ergonomic approach would be.”


    The PioneerLab is Airbus Helicopters’ new twin-engine technology demonstrator based on the twin-engine H145. The company says that it complements Airbus’ range of FlightLabs and focuses on testing technologies that reduce helicopter emissions, increase autonomy and integrate bio-based materials.

    The PioneerLab aims to demonstrate a fuel reduction of up to 30% compared to a conventional H145, thanks to a hybrid electric propulsion system and aerodynamic improvements. Aboard the demonstrator, Airbus Helicopters will also flight-test structural components made from bio-based and recycled materials, which aim to reduce the environmental footprint across the entire aircraft life cycle.

    PioneerLab is partially co-funded by the German government, through the national research program LuFo.

    The PioneerLab’s flight campaign has already begun at Airbus’s largest German site in Donauwörth, with a rotor strike alerting system being the first element tested on board the demonstrator. The next phase will be to test an automated take-off and landing system.


    Another important application of human factors is in operations. At Airbus Commercial Aircraft, the emphasis is on flight crew resilience training to reduce risks associated with human performance, according to the aerospace OEM.

    One of the main elements of its strategy is to promote safety and develop training to support the various players in the sector, in particular operators.

    It explains that during operations, pilots can be exposed to unexpected disturbances that may result in temporary performance lapse. This is where resilience training for pilots comes into play. The aim is to enable pilots to maintain a sufficient safety margin at all times through the actions they take in such situations.

    This mainly depends on how they communicate, how they manage their workload and take decisions, illustrating resilience in the face of unexpected disturbances and how they deal with threats and errors.

    While flight crews cannot be trained to react to every specific situation, they are prepared for a wide number of scenarios by developing specific skills. This should enable pilots to operate successfully in a complex and changing operational environment. They should also be able to handle unforeseen tasks and situations for which they have not been specifically trained. This builds resilience, Airbus says.

    Operations Engineer

    Related Companies

    This material is protected by MA Business copyright
    See Terms and Conditions.
    One-off usage is permitted but bulk copying is not.
    For multiple copies contact the sales team.