An Analysis of the Use of Elapsed Time Indicators in F/FB-111 Avionics Subsystems.

The use of Elapsed Time Indicators ETIs on Air Force aircraft subsystems is an outgrowth of the Air Forces growing concern for equipment reliability, which was spawned shortly after World War II. It was not until after the AGREE Report was published in 1957, however, that the use of ETIs gained momentum in the Air Force. Now ETIs are used on subsystems in every model of aircraft in the Air inventory. Electronic subsystems are particularly adaptable to the use of ETIs. Avionics subsystems make up the bulk of electronic subsystems on most aircraft, and it is here that most of the ETIs can usually be found on Air Force aircraft. By measuring the operating time on an electronic subsystem, elapsed time indicators provide time data, which combined with failure data, can be used in reliability and maintainability studies, in warranty enforcement, in actuarial analyses, and in maintenance planning, as well as some other applications. But while ETIs have a number of uses in theory, there is some question about how much use they actually receive in operational applications. The objective of this investigation, therefore, addresses the issue of whether the use of ETIs is beneficial to the Air Force.