Identifying the Essential Reliability, Availability, and Maintainability Tasks for Aerospace Systems
Date of Award
Fall October 2011
Campus Access only Research Projects
Master of Science
School or College
Seaver College of Science and Engineering
This report provides the essential Reliability, Availability, and Maintainability (RAM) tasks that can be applicable to all types of aerospace projects varying in contract cost and complexity. The drive for this study was to identify a set of tailorable tasks to apply towards smaller aerospace programs. Though the report is specifically focused on aerospace projects, these essential RAM tasks and principles can be applied across all types of complex systems that require a high level of reliability. Methods of analysis were primarily focused on comparing Northrop Grumman Aerospace System (NGAS) reliability processes to the commercial industries best practices for reliability. A paper study of reliability plans and interviews of key reliability engineers were used to baseline the reliability process at NGAS. To baseline the commercial industry processes, a paper study was performed on best practices and lessons learned.
Results indicate that NGAS processes for RAM are lean and effective. Over 16 programs plans were reviewed, which dated from the 1970's to current programs, and they all show a consistent process for conducting reliability analysis. On the contrary, the commercial industry RAM practices are inconsistent and are still being matured. Of the commercial industries reviewed, the nuclear power industry best matched the reliability processes with NGAS. Based on interviews and paper studies, the essential RAM activities are summed up by two activities, the Failure Modes and Effects Analysis (FMEA), and Reliability Predictions/ Analysis. These two tasks provide the highest value in achieving the programs reliability goals.
Current NGAS RAM practices match the best practices performed in the commercial industry, but tailoring and scope reduction is necessary when applying these practices for smaller aerospace programs. Based of program budget and complexity, this paper provides the recommendations for tailoring the essential reliability tasks, the FMEA and Reliability Predictions. Specific instructions were provided on how to tailor the essential reliability tasks to obtain the highest value based on the program budget and complexity. These basic instructions can be summarized as:
- All complex programs, regardless of budget should perform a functional FMEA. As complexity and budget increases, additional detailed FMEAs shall be performed for units of risk
- Based on the FMEA, a Critical Items List shall be created and managed to closure. It is vital that there is a plan to work off any reliability risks
- Part count method should be performed if budget and time are limited. Part stress method often uses outdated failure rate databases, causing over conservative predictions. There is higher value to the program to perform a part count method to identify areas of concern in the design
Cho, Daniel, "Identifying the Essential Reliability, Availability, and Maintainability Tasks for Aerospace Systems" (2011). LMU/LLS Theses and Dissertations. 379.