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  2. Maintainability Attribute Key System Attribute (KSA)/Additional Performance Attribute (APA)

Maintainability Attribute Key System Attribute (KSA)/Additional Performance Attribute (APA)

ALCL 074

DAU GLOSSARY DEFINITION

The ability of an item to be retained in, or restored to, a specified condition when maintenance is performed by personnel having specified skill levels, using prescribed procedures and resources, at each prescribed level of maintenance and repair.

General Information

Joint Capabilities Integration and Development System (JCIDS) Requirement

The August 2018 revision to the Manual for the Operation of JCIDS expanded the scope of the Sustainment Key Performance Parameter (KPP) to include Maintainability as either a KSA or APA (depending on the system or equipment requirements) along with the existing Reliability and Operating & Support (O&S) Cost attributes - which can also be either KSAs or APAs. The 2021 version of the JCIDS Manual also includes the Maintainability KSA/APA.

Starting with the Sustainment KPP...

The Sustainment KPP is expressed in terms of its perspectives of Materiel Availability (Am) and Operational Availability (Ao)

Am is the measure of the percentage of the total inventory of a system operationally capable, based on materiel condition, of performing an assigned mission, where AM = number of operationally available end items / total population of end items

Ao is the measure of the percentage of time that a system or group of systems within a unit are operationally capable of performing an assigned mission, where AO = Uptime / (Uptime + Downtime)

The supporting Reliability, Maintainability, and O&S Cost attributes ensure that the Sustainment KPP is achievable and affordable in its operational and support environment. Together, the Sustainment KPP and its supporting KSAs/APPs ensure early sustainment planning, enabling the requirements and acquisition communities to provide a capability solution with optimal system performance and supportability to the warfighter at an affordable life cycle cost.

Reliability, Maintainability and Cost Trade Space

As shown in Figure 1, the Reliability and Maintainability attributes bound the trade space for their respective functional and performance profiles while mindfully balancing the O&S Cost KSA/APP. 

Figure 1. Reliability, Maintainability and Cost Trade Space

The interaction of the KSA/APAs result in a balanced trade space for 'designing in' performance, supportability and affordability over the life cycle. The 'directionality' of the Reliability and Maintainability parameters as shown is important, as the shared goal of those parameters is to maximize Reliability, i.e., to minimize the number of failures, while minimizing the sustainment cycle time to achieve the shortest downtimes possible, as measured by metrics such as Mean Down Time (MDT) and Mean Time To Repair (MTTR). Accordingly, Reliability design considerations focus on parts reliability, stress derating and concepts such as redundancy. Maintainability design considerations focus on both corrective and preventive maintenance, as enabled by its three attributes of modularity, accessibility and testability.

Maintainability Attribute Definitions

Table 1 presents the Maintainability Attribute definitions as defined in the JCIDS Manual.  

Table 1. Maintainability Attribute Definitions

Maintabilability Engineering Best Practices

While not identified as part of the Maintainability attribute, the following Maintainability design attributes form the basis of Maintainability Engineering best practices as presented in Table 2.

Table 2. Maintainability Design Attributes and Objectives

I

Paragraph 3.3.4 of the JCIDS Manual provides additional details regarding the implementation and effectiveness of the Maintainability attribute as an enabler of the maintenance concept and the maintenance plan, to include supply chain attributes.

Summary

In closing, the addition of Maintainability as a KSA /APA is a significant enhancement to the Sustainment KPP as it establishes Built-In-Test (BIT) and its related functionality as design criteria to achieve the rapid restoral of service, thereby enhancing availability. This update to the JCIDS Manual broadens the scope and impact of the Sustainment KPP and promotes greater technical interaction the Engineering, Test & Evaluation (T&E) and Life Cycle Logistics communities, as the Maintainability attribute establishes design criteria common to all three communities.