Photo: Salas O’Brien assesses NASA’s mission critical assets supporting spaceflight launches. Salas O’Brien is a NASA Silver Group Achievement Award recipient for their work on the new liquid hydrogen sphere supporting the Artemis Program. (Source: NASA)  Contributors: Aaron Thompson, Terry Tullis, Tim Gutman

Managing aging infrastructure within budget constraints is a complex challenge for many organizations. As assets deteriorate, maintenance costs rise, requiring innovative strategies that balance reliability with financial responsibility. Tiered maintenance (TM) offers a structured approach by categorizing facilities based on their mission relevancy, allowing for more strategic planning and resource allocation. Salas O’Brien’s collaboration with NASA demonstrates the effectiveness of TM in optimizing asset management, improving resource allocation, and enhancing the reliability of mission-critical systems.

Case study: NASA’s tiered maintenance journey with Salas O’Brien

NASA’s Office of Strategic Infrastructure (OSI) is working to improve the affordability and mission readiness of its real property portfolio. With a flat, inflation-impacted operations and maintenance (O&M) budget and an estimated annual maintenance gap of nearly $300 million, the agency faces growing challenges. Compounding the issue, 83% of NASA’s facilities have exceeded their expected lifespan.

To address these constraints, NASA partnered with Salas O’Brien to refine and implement its tiered maintenance concept, a strategy designed to prioritize maintenance efforts based on mission relevancy. NASA’s Facilities and Real Estate Division (FRED) tasked our team with developing a tiered maintenance policy—a standardized framework that aligns maintenance strategies across all NASA centers and facilities.

Salas O’Brien’s approach began with analyzing the NASA Agency Master Plan to assess TM’s impact on funding and budget allocation. We then developed a tiered maintenance process and an equipment asset criticality analysis (EACA) procedure, providing a data-driven methodology for evaluating equipment based on failure risk and operational consequences.

As a final step, we revised NASA Interim Directive NID 8831.124, which governs condition-based maintenance and training for facility managers. The updated directive establishes clear guidelines for facility tiering, equipment criticality rankings, and minimum maintenance levels—ensuring resources are directed where they’re needed most.

By implementing a structured approach to asset management, NASA is enhancing maintenance efficiency, optimizing resource allocation, and strengthening the reliability of its mission-critical infrastructure.

Understanding NASA’s tiered maintenance framework

Tiered maintenance is a strategic, engineering-based approach that classifies facilities into hierarchical tiers. Salas O’Brien facilities engineers use TM to assign criticality scores to equipment assets according to their impact on that center’s specific mission and any associated risk. TM-based asset classifications help organizations focus maintenance efforts on the most critical facilities and assets, ensuring operational continuity while managing costs effectively. These requirements fall under the application of reliability-centered maintenance (RCM), including condition-based maintenance (CBM), preventive maintenance (PM), and reactive maintenance.

Three key aspects of tiered maintenance

1. Facility Tiering

NASA FRED visited each site and assigned facility tiers according to a scoring criterion. These tiers are broken down into four levels and can be tailored to an organization’s specific needs. NASA’s facility asset classification, based on mission relevancy (MR), is calculated per the following formula:

MR = User Demand + Mission Need + Interruptability + Redundancy + Future Mission Need

The facility is then assigned a tier based on its MR score.

  • Tier 1 facilities are mission-relevant and include critical infrastructure, utility plants, space simulators, command centers, test stands, high pressure gas facilities, communication towers and antennas, mission launch and control facilities, and irreplaceable national treasures. The maintenance program Salas O’Brien develops for Tier 1 facilities aims to maintain or improve the facility condition index (FCI).
  • Tier 2 facilities are mission-essential, such as support services, component shops, laboratories, fabrication shops, and non-critical infrastructure. The Central Air Equipment Building at Glenn Research Center is a good example, which scored at the upper threshold of a Tier 2 facility with a Mission Relevancy Score of 268. The goal for maintaining these facilities is to sustain the FC.
  • Tier 3 facilities are important but non-mission essential, including office spaces, fitness centers, historical facilities, climate-controlled warehouses, and other noncritical facilities. An example of a Tier 3 facility is the Heavy Equipment Maintenance Building at White Sands Test Facility in New Mexico. The maintenance goal here is to manage asset availability and reliability, with an allowance for a possible FCI decrease of less than 5% over five years.
  • Tier 4 facilities are non-essential, encompassing low mission relevance score facilities, including non-climate-controlled storage and facilities placed in standby, mothballed, and abandoned statuses. The maintenance focus for these facilities is on relevant asset maintenance at minimum service levels, permitting a possible FCI decrease of more than 5% over five years. When new facilities are constructed, each center’s master planners provide the necessary information to generate an MR score, determining the facility’s tier. MR scores are reviewed regularly to adjust facility tiers as needed.
NASA’s facility counts by tier

2. Equipment Asset Criticality Assessment (EACA)

Each asset undergoes a detailed EACA to determine its criticality and assign the minimum service level outlined in NID 8831.124. The analysis considers factors such as safety, environmental impact, mission relevance, downtime implications, and repair/replacement costs. An EACA requires Salas O’Brien’s facilities engineers to visit each NASA center to conduct in-person interviews with the center director, facility managers, subject matter experts, technicians, and various other stakeholders. The team uses the CMMS Master Equipment List to conduct visual verification and inspection of the equipment, and to verify the data fidelity of the list. Salas O’Brien then assigns each facility asset a criticality level ranked from 1 (highest) to 4 (lowest).

Equipment assets (EA) assigned high levels are considered more critical and therefore receive a higher allocation of resources. While EAs with lower criticality levels also receive resources and priority, their allocation is adjusted according to their lower ranking. Once a criticality ranking is established, it remains unchanged unless the facility asset’s mission is changed (e.g. a high bay is renovated and now supports hazardous propellant loading operations). When such changes occur, the ranking for each affected facility is flagged for review and update to meet the site’s new needs. These reviews are part of the site’s management of change procedure.

3. Maintenance Planning

This final aspect is where the practicality of the plan is determined. If the maintenance job plans are not updated and adjusted to align with the new criteria, then all the effort invested in the plan will be futile. Maintenance activities must be tailored to each tier and criticality ranking, with higher-tier assets receiving more extensive maintenance.

Examples:

  • For Level 1 critical equipment, actions include condition or continuous-based monitoring, more frequent preventive maintenance, stocking more spare parts, and performing Root Cause Analysis (RCA) upon failure resulting in loss of availability during a required mission.
  • For Level 2 equipment, actions involve less frequent predictive and preventive maintenance, fewer spare parts, and less frequent condition-based monitoring.
  • For Level 3 equipment, actions may include running to failure, staying informed of local sources that maintain healthy inventories, and minimal predictive and preventive maintenance with no condition monitoring.
  • For Level 4 non-critical equipment, actions are limited reactive maintenance and repairing facility assets after discovery of failure.

Regardless of criticality level, Salas O’Brien collaborates with NASA to maintain all required security/anti-terrorism/force protection, life safety, fire protection, environmental, regulatory, and code compliance assets.

Benefits of tiered maintenance

The implementation of tiered maintenance brings several benefits, particularly for organizations with extensive and diverse asset portfolios:

  • Optimized resource allocation. By categorizing facilities and prioritizing critical assets, organizations ensure that their maintenance resources are directed where they are most needed, reducing waste and preventing under-maintenance or over-maintenance of assets.
  • Cost efficiency. Tiered Maintenance allows for significant cost savings by reducing the frequency and intensity of maintenance for non-essential assets, reallocating those savings towards maintaining critical assets through predictive maintenance (PdM) strategies such as condition-based maintenance (CBM) and predictive testing & inspection (PT&I). This has the potential to drive down repair costs by nearly 66%. NASA has already realized a positive impact through an agency-wide cost avoidance determination exceeding $50M for all centers after applying TM.
  • Enhanced reliability. Focusing on preventive and predictive maintenance for critical assets reduces the likelihood of unexpected failures, ensuring that these assets remain operational when needed.
  • Data-driven decisions. The systematic approach to categorizing and rating assets facilitates data-driven maintenance planning, enhancing transparency and improving management buy-in.

Overview of the EACA initiative

Since 2022, NASA has awarded Salas O’Brien multiple contracts to conduct EACA at various NASA locations.

Phase I

  • Scope: Establishment of the NASA Interim Directive NID 8831.124, along with defining and implementing the EACA scoring system and methodology.
  • Locations: Goddard Space Flight Center (GSFC), Wallops Flight Facility (WFF), and White Sands Test Facility (WSTF).
  • Contract Value: $1,826,557

Phase II

  • Scope: EACA scoring for assets at Armstrong Flight Research Center (AFRC), Kennedy Space Center (KSC), Johnson Space Center (JSC), and Marshall Space Flight Center (MSFC).
  • Contract Value: $1,284,931

Phase III

  • Scope: EACA scoring for equipment at Ames Research Center (ARC), Glenn Research Center (GRC), Langley Research Center (LaRC), Michoud Assembly Facility (MAF), and Stennis Space Center (SSC).
  • Contract Value: $1,565,707
Salas O’Brien performed all three EACA execution phases exceptionally well. The project management efforts demonstrated by Tim Gutman and Terry Tullis was stellar. Their efforts resulted in all three phases being completed either on time or ahead of schedule and within budget. Besides the overall objective of assigning standardized criticality levels to each Center’s equipment assets, the Salas O’Brien team went the extra step in teaching the Center’s assigned system asset owners the ins and outs of the agency-tiered maintenance program, to include the TM/EACA policy and processes. Job well done.
Michael StitesAgency RCM Program Manager

Reliability-centered maintenance

In addition to EACA, Salas O’Brien performs RCM studies focusing on updating over 800 maintenance job plans in line with NASA’s Tiered Maintenance framework. Our study includes labor cost analysis, return on investment (ROI) projections, and alignment with NASA’s current maintenance objectives by facility criticality.

RCM Study Contract Value: $1,126,176.
Total EACA/RCM Contract Value: $5,803,371.
Key Salas O’Brien Achievements:
• NID 8831.134 policy development governing maintenance practices.
• EACA scoring for over 320,000 equipment assets across all NASA locations.
• Creation of new and gap analysis of existing preventive maintenance job plans for over 800 equipment items at MSFC.

Salas O’Brien engineers conducting an asset verification and criticality assessment at NASA Michoud Assembly Facility.

 

Future directions and implications 

As organizations continue to adopt tiered maintenance, the role of data-driven decision-making becomes increasingly important. The integration of advanced technologies, such as internet of things (IoT) sensors and artificial intelligence (AI)-driven analytics, further enhances our ability to monitor asset conditions in real-time, enabling more precise and proactive maintenance interventions.

For Salas O’Brien, the success of the TM, EACA, and RCM initiatives at NASA highlights the potential of tiered maintenance to transform facility and asset management practices across industries. By focusing on critical assets and leveraging robust data frameworks, organizations can achieve greater efficiency, reduce costs, and enhance operational reliability.

Conclusion 

NASA forecasts a 45% reduction in their maintenance funding gap over the next five years. After 10 years, NASA expects a 75% maintenance gap reduction as well as reducing deferred maintenance obligations by $810M.

Tiered maintenance offers a comprehensive approach to facility and asset management that prioritizes mission relevancy and criticality. Salas O’Brien’s work with NASA exemplifies the tangible benefits of this strategy, demonstrating our ability to enhance reliability, optimize resource allocation, and drive cost savings.

As the demand for efficient asset management continues to grow, tiered maintenance plays a pivotal role in helping organizations navigate the complexities of maintaining aging infrastructure within budget constraints. Through strategic prioritization and data-driven insights, tiered maintenance provides a pathway to sustainable, efficient, and reliable asset management.

How Salas O’Brien can help

Salas O’Brien specializes in delivering tailored maintenance strategies that address the unique challenges and needs of a facilities O&M organization. By leveraging our expertise in tiered maintenance, we help clients optimize their asset management processes, ensuring that resources are allocated efficiently and effectively.

Reach out to our contributors below to talk about your project.

Contributors
Aaron Thompson, CMRP, CRL

Aaron Thompson, CMRP, CRL

Aaron Thompson has over 17 years of experience in reliability, maintainability, and technical engineering, and is a senior professional in the aerospace and defense industry. He uses his expertise in reliability analysis, root cause analysis, failure modes and effects criticality analysis, and reliability centered maintenance to deliver optimal solutions for complex and critical systems and projects. His mission is to ensure the highest standards of reliability, safety, and performance for the people, systems, and assets that he works with, while also reducing costs, risks, and downtime. Aaron serves as a Reliability Engineer at Salas O’Brien. Contact him at [email protected] .

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Tim Gutman, CSP, PMP, CPE, CFPS

Tim Gutman, CSP, PMP, CPE, CFPS

Tim Gutman brings 23 years of experience with Salas O’Brien delivering system safety, failure analytics, equipment reliability, and O&M optimization for aerospace, commercial, and federal clients. His current focus is on delivering criticality and tiered maintenance strategies across all NASA centers and facilities. Tim serves as a Vice President and Program Manager at Salas O’Brien. Contact him at [email protected] .

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Terry Tullis, PE, LEED AP

Terry Tullis, PE, LEED AP

Terry Tullis leads the Sustaining Engineering Services business line at Salas O’Brien’s Merritt Island office. With over 19 years of experience with Salas O’Brien, he provides facilities engineering services to commercial and federal clients. Terry brings in-depth knowledge of RCM, O&M optimization, criticality analyses, and sustainability services. Terry’s strategic focus on O&M optimization and energy efficiency drives operational effectiveness for his clients. Terry serves as Director of Sustaining Engineering Services and Vice President at Salas O’Brien. Contact him at [email protected].

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