(Formerly Maintenance Error Decision Aid)

Definition

The Maintenance Event Decision Aid (MEDA) is a structured process used to investigate events caused by maintenance technician and/or inspector performance.

Description

Developed originally by the Boeing Company in the early 1990s with the active involvement of three major international airlines, a maintenance staff trade union, and the U.S. Federal Aviation Administration (FAA), MEDA was the first structured attempt to enhance the value derived from investigation of maintenance error by providing a process in which undesirable human behavior was placed in its full procedural context. It has since been widely adopted - and adapted - as a basis, achieving effective maintenance error investigations worldwide.

The MEDA method was developed as a more effective alternative to simply ‘retraining’ employees found to have made maintenance errors. It was realised that by the time a specific individual had been identified as responsible for an error, information about the factors that contributed to the error had often been lost. It was concluded that if the factors which contributed to an error remained, then similar errors would be likely to recur.

The MEDA philosophy is that these events are caused by mechanic/inspector errors and/or violations (intentionally not following established company policies, processes, and procedures). These errors and violations are caused by contributing factors in the workplace, such as poorly written maintenance procedures, not having the right tool or equipment to do the job, time pressure, task interruption, and poor communication. Two Boeing-copyrighted MEDA tools are freely available to the public. The first is the MEDA User's Guide, which is a "how-to" manual on carrying out a MEDA investigation. The second is the MEDA Results Form, which is used to collect contributing factors information from interviews with the mechanic(s) or inspector who performed the work on the aircraft or saw the work being done.

Boeing describes the MEDA philosophy as being based on three assumptions:

• That people want to do the best job possible and do not make errors intentionally; violations do not occur randomly; they occur due to various contributing factors.

Investigators will get more help from employees who do not feel their competence and integrity are in question. The employees are more likely to be helpful in identifying the factors that might have contributed to an error and in suggesting possible solutions.

• That a series of factors is likely to contribute to an error or a violation.

Findings on the context of a particular error investigation may have much wider significance for the occurrence of errors generally. Often, matters like difficulty in understanding of documentation (job cards, the aircraft maintenance manual, the illustrated parts catalogue or the applicable component maintenance manual), inadequate lighting, poor shift handover or aircraft design issues may be disclosed in an investigation. "Fixing" just some of the identified factors will probably be able to significantly reduce the likelihood of most types of error recurring.

• Once they are revealed through investigation, most of the factors which contribute to an error or a violation can be managed.

Involvement of employees close to an error or a violation in the investigation of it helps to establish how to manage the issues. Processes can be changed, procedures improved or corrected, facilities enhanced and best practices shared.

The MEDA process is described as having five key stages:

• Selection of the technical event to be investigated by the maintenance organisation involved
• Decision on whether the event identified was maintenance-related
• Investigation using the MEDA results form to record relevant information about the event which disclosed the error(s) and/or violation(s) that caused the event, the factors contributing to the errors/violations and a list of possible prevention strategies.
• Prevention Strategies review leads to prioritising, implementation and tracking of process improvements
• Feedback to the workforce advises what changes have been made, explains the value of employee participation and shares the results of the investigation.