The authors set out to design a tool that could be used to capture the factors that contribute to error in maintenance. They realized that the cause of error was rarely just one reason, but a process made up of a series of circumstances, and when aligned, had the potential to become an incident or an accident. They wanted to design a process that not only highlighted the error itself, but looked at what other factors led to the incident/accident. Highlighting and analyzing the causes would allow the correct actions to be taken with the possibility to reduce or eliminate future incidents/accidents.
The MEDA process was the outcome of this thought process and the article discusses the evaluation results from field testing the MEDA tool.
Results
In the field test survey participants were asked a series of questions regarding the support they received in their maintenance environment.
| Environmental Elements | Agree % | Not Sure % | Disagree % |
|---|---|---|---|
| Written materials are available as necessary | 77 | 12 | 11 |
| Lessons learned from errors are shared | 48 | 19 | 33 |
| Technical kept informed about problem areas for errors | 46 | 22 | 32 |
| Written material is presented in understandable formats | 43 | 38 | 29 |
| Technical receive effective support from organizations | 34 | 29 | 37 |
| Technical not afraid to admit errors | 29 | 21 | 50 |
| Technical receive feedback from supervisor about performance | 22 | 24 | 54 |
| Technical are satisfied with their working environment | 29 | 21 | 50 |
| Technical are satisfied with their working environment | 29 | 21 | 50 |
| Punishment is often used to discipline technicians | 45 | NR | NR |
| Disciplinary actions are fairly applied and justified | 22 | 35 | 43 |
| Punishment usually results in improved performance | 9 | 28 | 63 |
NR=not reported
Next a 'tool survey' was administered, the intention was to find out if participants found the MEDA process easy to use.
| MEDA Process | Agree % | Not sure / Disagree % |
| Uses familiar words & terms | 85 | 15 |
| Documentation was understandable | 83 | 17 |
| Documentation was complete | 76 | 24 |
| Sufficient instructions on how to use the process | 69 | 31 |
| Use of listing existing barriers to error that failed on Results Form | 67 | 33 |
Next questions were asked regarding using MEDA for investigations.
| MEDA Usage | Agree % | Not Sure % | Disagree % |
|---|---|---|---|
| The results of the analysis were understandable to me | 74 | 25 | 1 |
| The results of the analysis are applicable | 74 | 24 | 2 |
| The Results Form helped me identify contributing factors | 71 | 29 | 0 |
| I found MEDA easy to use | 65 | 28 | 7 |
| MEDA guided me in identifying technician error | 63 | 23 | 4 |
| MEDA guided me in identifying corrective actions | 57 | 40 | 3 |
| I had cooperation from employees while using MEDA | 52 | 44 | 4 |
Participants were then asked questions regarding whether MEDA had been accepted as a reporting tool and were they likely to use it?
| MEDA Acceptance | Agree % | Not Sure % | Disagree % |
|---|---|---|---|
| MEDA will yield standardized results | 75 | 22 | 3 |
| MEDA could replace current error investigation method | 72 | 24 | 4 |
| Job environment will improve because of MEDA | 68 | 27 | 5 |
| Maintenance error will reduce because of MEDA | 58 | 35 | 7 |
| MEDA investigations are supported by management | 57 | 41 | 2 |
| Maintenance error investigations will increase because of MEDA | 57 | 34 | 9 |
| Will be less punitive action because of MEDA | 35 | 54 | 11 |
| MEDA will be accepted in my job environment | 34 | 53 | 13 |
| Because of MEDA, will be new corrective actions | 32 | 61 | 7 |
Post maintenance technician interviews the Subject Survey was distributed to the interviewees with the aim to gather information regarding maintenance technician involvement in the MEDA process.
| MEDA Involvement | Agree % | Not Sure % | Disagree % |
|---|---|---|---|
| I did not feel intimidated by the use of MEDA | 88 | 5 | 7 |
| I thought it was useful to discuss existing barriers | 75 | 25 | 0 |
| The purpose of using MEDA was made clear | 65 | 23 | 12 |
| MEDA documentation was made available to me | 60 | 7 | 33 |
| Using MEDA did not create more work for me | 57 | 33 | 0 |
| MEDA documentation was understandable | 53 | 35 | 8 |
| MEDA helped in identifying contributing factors | 12 | 50 | 38 |
| The results of the analysis were understandable | 28 | 59 | 13 |
| Results of the analysis were made available to me | 36 | 43 | 21 |
Airline managers were asked to participate in the Airline Management Survey which addressed the issue of implementing the MEDA reporting system.
| Management Observations of MEDA | Agree % | Not Sure % | Disagree % |
|---|---|---|---|
| I fully agree with the MEDA philosophy | 92 | 8 | 0 |
| I understand how MEDA investigations are done | 67 | 9 | 24 |
| Airline has done a good job in MEDA implementation | 50 | 34 | 16 |
| Strong acceptance of MEDA by Management | 85 | 15 | 0 |
| Strong acceptance of MEDA by technicians | 42 | 42 | 16 |
| I have seen positive benefits from MEDA | 42 | 58 | 0 |
| I strongly support the continued use of MEDA | 77 | 23 | 0 |
| Other airlines should adopt MEDA | 75 | 25 | 0 |
| It is important for airlines to share MEDA results | 69 | 31 | 0 |
| My airline will keep MEDA after field test | 38 | 62 | 0 |
The final survey administered to MEDA investigators was the Field Test Follow-up Survey and this contained seven of the same questions asked of the Management.
| Investigator Observations of MEDA | Agree % | Not Sure % | Disagree % |
|---|---|---|---|
| Airline has done a good job in MEDA implementation | 18 | 53 | 29 |
| Strong acceptance of MEDA by technicians | 17 | 46 | 37 |
| Strong acceptance of MEDA by Management | 33 | 39 | 28 |
| I have seen positive benefits from MEDA | 20 | 40 | 40 |
| I strongly support the continued use of MEDA | 56 | 25 | 19 |
| Other airlines should adopt MEDA | 45 | 40 | 15 |
| My airline will keep MEDA after field test | 22 | 65 | 13 |
The researchers then compared answers between management and the MEDA investigators in order to gauge opinions.
| MEDA Comparison | Management Agree % | Investigator Agree % |
|---|---|---|
| Airline has done a good job in MEDA implementation | 50 | 18 |
| Strong acceptance of MEDA by technicians | 43 | 17 |
| Strong acceptance of MEDA by Management | 85 | 33 |
| I have seen positive benefits from MEDA | 42 | 20 |
| I strongly support the continued use of MEDA | 77 | 56 |
| Other airlines should adopt MEDA | 75 | 45 |
| My airline will keep MEDA after field test | 38 | 22 |
Methods
Research Approach
Exploratory research using quantitative and qualitative data collection methods.
The authors set out to exam whether the Maintenance Error Decision Aid was effective in highlighting the factors which cause maintenance error and whether after understanding what caused the error change could be made to prevent reoccurrence. The authors conducted a field test of the decision aid using several different methods to collect data, which included:
- five different surveys
- two interviews
- completed MEDA results form
Sample
The MEDA process was field tested by employees across eight airlines and one repair station. Sample size varied depending on the survey being administered.
- Field test survey - 248 airline employees pre MEDA process usage
- Tool Survey - 237 airline employees post MEDA process usage (participants being the ones to use the process)
- Subject Survey - post maintenance technician interview they were asked to complete the survey, 17 were returned (it was not mentioned how many were administered)
- Airline Management Survey - 13 surveys returned from the nine airlines (does not indicate how many were administered or how the nine returned were distributed)
- Field Follow-up Survey - 49 returned by MEDA investigators (during the last month of the field test). (Does not indicate how many were administered)
Design
Non-experimental with an aspect of longitudinal design (surveying and resurveying the same participants) using quantitative and qualitative methods of data collection.
Variables
The results Form is the dependent variable and the error being reported is the independent variable.
In this study there is no control over the dependent variable, therefore confounding variables cannot be managed. However, the MEDA process relies on the facts of the error being reported, and the opinions of the investigator, and cannot eliminate external factors.
Procedure
A working party, made up of people from aircraft manufacturer, airlines and the national regulatory authority, designed and developed the MEDA process which was to be used to investigate maintenance error. From this working group came a Results Form and a User's Guide.
The Results Form is what is used to report the incident/accident and is designed to gather information not only from the incident itself, but what could be classed as contributing factors.
Field evaluation was the main goal of the authors. They were looking to assess how the MEDA process was received by the industry and this was achieved by evaluating the data collected, from several different collection methods, across different airlines.
1. Surveys
- Field Test Survey
a pre survey administered to technicians before they became 'investigators' and before using the MEDA investigative process. Collected opinions on maintenance error and airline maintenance programs.
- Tool Survey
post survey administered to 'investigators' after the used the MEDA investigative process. Collected opinions about using the MEDA Results Form.
- Subject Survey
administered to the technician who made the error, who was interviewed as part of the investigation process. Collected their opinions regarding the MEDA process.
- Management Survey
Filled out by Maintenance Managers. Collected opinions on their acceptance of the MEDA process and how highly they rated the importance of contributing factors.
- Follow-up Survey
Filled out by the investigators who used the MEDA process and re-asked several of the questions form the Field Test Survey, but of course this time after experiencing the MEDA process.
2. Analysis of completed Result Forms
Looked at for completeness, content of information supplied, amount of information supplied and relevance of informations supplied.
3. Meetings
During and post meetings were held to evaluate the MEDA process. The intention was to receive feedback from the selected airlines on the MEDA process from the persons involved in the MEDA process trial.
Data analysis
Following a variety of data analysis, research results were reported in the form of pictorial tabulated results.
- Qualitative analysis was conducted through Result Form review and participant interviews (although the interviews were more to do with the MEDA process and then assessed with surveys post interview).
- Quantitative analysis through the use of surveys and tabulating the response percentage.
- Follow-up Survey checked for statistical significance in its comparison between Manager and technician opinions.
Generalization potential
The developers of the MEDA process carried out field analysis across several different airlines in different countries. Generally the authors showed that the MEDA process could be used by any airline and the results obtained could be trusted.
There was a significant difference in opinions between managers and technicians in the follow-up survey, showing that technicians were reasonably negative in comparison to managers. However the sample size was relatively small and the authors did not provide information on who returned the surveys for analysis.
Want to know more?
- Boeing - Maintenance Error Decision Aid (MEDA) Users Guide (http://www.hf.faa.gov/opsmanual/assets/pdfs/MEDA_guide.pdf)
- Explains what error is, what MEDA is, why it should be used, how to use it effectively and how to carry out an investigation.
- MEDA - Investigation Process (http://www.boeing.com/commercial/aeromagazine/articles/qtr_2_07/article_03_1.html)
- A guide to what MEDA is, the philosophy behind it and how to utilize the tool to get the most out of it.
Contributors to this page
K. Twyman
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