Human factors design for maintainability and in-service support
Over the past several years, airplane maintenance has benefited from an increased focus on how human factors can contribute to safety and operational efficiency. In maintenance, as in flight deck design, Boeing employs a variety of sources to address human factors issues, including
- Chief mechanic participation.
- Computer-based maintainability design tools.
- Fault information team.
- Customer support processes.
Chief mechanic participation.
Modeled on the role of chief pilot, a chief mechanic was appointed to the 777 program and to all subsequent airplane programs (717, 737-600/-700/ -800/-900, 757-300, and 767-400 Extended Range [ER]). As with the chief pilot, the mechanic acts as an advocate for operator or repair station counterparts. The appointment of a chief mechanic grew out of the recognition that the maintenance community contributes significantly to the success of airline operations in both safety and on-time performance. Drawing on the experience of airline and production mechanics, reliability and maintainability engineers, and human factors specialists, the chief mechanic oversees the implementation of all maintenance-related features.
Computer-based maintainability design tools.
Beginning with the 777 program, Boeing stopped building full-scale airplane mockups, which in the past helped determine whether a mechanic could reach an airplane part for removal and re-installation. Now, using a computer-aided three-dimensional interactive application (CATIA), Boeing makes this type of determination using a human model. During design of the 737-600/ -700/-800/-900, Boeing used human modeling analysis to determine that the electrical/electronic bay needed to be redesigned to allow a mechanic to access all wire bundles for the expanded set of avionics associated with the updated flight deck concept (fig. 2). In addition to ensuring access and visibility, human factors specialists conduct ergonomic analyses to assess the human capability to perform maintenance procedures under different circumstances. For example, when a mechanic needs to turn a valve from an awkward position, it is important that the force required to turn the valve must be within the mechanic's capability in that posture. For another example, when a maintenance operation must be accomplished in poor weather at night, secure footing and appropriate handling forces are necessary to protect the mechanic from a fall or from dropping a piece of equipment.
Fault information team (FIT).
Human factors considerations in maintenance also led to the formation of the FIT. During development of the 737-600/-700/-800/-900, Boeing chartered the FIT to promote effective presentation of maintenance-related information, including built-in test equipment (BITE) and maintenance documentation. The FIT charter has since expanded to promote consistency in maintenance processes and design across all systems and models. The goal is to enable mechanics to maintain all Boeing commercial airplanes as efficiently and accurately as possible. This cross-functional team has representatives from maintenance, engineering, human factors, and operators. One of the team’s primary functions is to administer and update standards that promote uniformity among Boeing airplane maintenance displays. For the text of these displays, Boeing has created templates that provide for common fault menus for all systems.
The interface should look the same to the mechanic regardless of the vendor or engineering organization that designs the component. Engineers responsible for airplane system design coordinate their BITE and maintenance design efforts with the FIT. The FIT reviews all information used by the mechanic, including placards, manuals, training, and size, location, and layout of controls and indicators, and works with the engineers to develop effective, consistent displays. The team also provides input and updates to Boeing design standards and requirements.
Customer support processes.
In the early 1990s, Boeing formed a maintenance human factors group. One of the group’s major objectives was to help operators implement the Maintenance Error Decision Aid (MEDA) process. The group also helps maintenance engineers improve their maintenance products, including Aircraft Maintenance Manuals, fault isolation manuals, and service bulletins. As maintenance support becomes more electronical based, human factors considerations have become an integral part of the boeing design process for tools such as the Portable Maintenance Aid. In addition, the group is developing a human factors awareness training program for Boeing maintenance engineers to help them benefit from human factors principles and applications in their customer support work.
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