Human Systems Integration Division @ NASA Ames

Maintenance is the process of ensuring that a system continues to perform its intended function at its designed-in level of safety and reliability (Kinnison, 2004). Without the intervention of maintenance personnel, equipment used in complex technological systems such as aviation, rail transport, and medicine would drift towards a level of unreliability that would rapidly threaten safety and profitability.

Although maintenance makes an essential contribution to system reliability, the benefits of maintenance come at a price and ironically, maintenance is also a major cause of system failure. The rate of power station outages increases shortly after maintenance (Smith, 1992), maintenance quality is a major concern in the chemical industry (Kletz, 2001), and in aviation there is evidence to suggest that maintenance is contributing to an increasing proportion of accidents (Human Factors Programs, 2002). Furthermore, as automated systems become increasingly common, humans are generally assigned a reduced role as direct controllers of machinery, leaving maintenance as a major remaining point of direct interaction between humans and technology, where human capabilities and limitations can have a significant impact on system safety and reliability.

Obtaining information on maintenance human factors can be notoriously difficult. In many organisations, a punitive culture has discouraged open communication about incidents, and common errors (such as an unsecured oil filler cap) may result in several days without pay, or even instant dismissal. Furthermore, months or years may pass before a maintenance error is detected, making it especially difficult to identify the human factors involved in the events. In some cases investigators have been unable to determine the actions or even the individuals involved in a maintenance irregularity. Unlike pilots or controllers, the activities of maintainers are not recorded for later replay. In this paper we describe the development and validation of a questionnaire that was designed to collect information on maintenance human factors that would be otherwise unobtainable.