Serviceability is the ease or difficulty with which an equipment can be repaired

Intuitively, it would seem that some term should be used to represent the degree of ease or difficulty with which an equipment can be repaired. The term “serviceability” has been selected for this concept. Serviceability has a strong influence on repairability, but the two are essentially different concepts. Serviceability is an equipment design characteristic,
while repairability is a probability involving certain categories of time.

Although the definition of serviceability is stated in a manner that suggests a quantitative concept, it is often necessary to accept a qualitative evaluation of the serviceability of an equipment. The definition as given does accentuate the idea that comparison of equipments can yield a conclusion that “Equipment A is more serviceable than Equipment B.”

Actually, this kind of conclusion may be entirely satisfactory, since the numerical evaluation can be made when repairability is measured. That is to say, the better the serviceability, the shorter the active repair time. Hence, repairability is a reflection of serviceability even though the two concepts are quite distinct.

Serviceability is dependent on many hardware characteristics, such as engineering design, complexity, number and accessibility of test points, and the like. These characteristics are under engineering control, and poor serviceability traceable to such items is the responsibility of design engineers. However, many other characteristics which can cause poor serviceability are not directly under the control of the design engineers.
These include lack of proper tools and testing facilities, shortage of work space in the maintenance shop, poorly trained maintenance personnel, shortage of repair parts, and other factors that can increase the difficulties of maintenance.

References:

1. MIL-HDBK-338, Electronic Reliability Design Handbook, 15 Oct 84
2. MIL-STD-721, Definitions of Terms for Reliability and Maintainability, 23 Oct 91