This SAE Aerospace Standard (AS) specifies requirements for the interface between a rotational system indexing sensor and its interface electronics. These sensors generate one or more electrical pulses for each revolution of the shaft being monitored. These pulses can be used to determine the actual shaft rotational speed and/or position for use in a Health and Usage Monitoring System (HUMS). Indexing sensors are used in the following HUMS areas on the aircraft: (a) rotor track and balance, (b) engine vibration monitoring and diagnostics, (c) drive train vibration monitoring and diagnostics. The goal of this standardization effort is to be able to take any compliant indexing sensor and connect it to any compliant interface electronics.

These SAE HUMS Interface Specifications include the minimal interface and performance requirements for interoperability with the Rotorcraft Industry Technology Association (RITA) compliant HUMS. Compliance with these Interface Specifications can be referenced in more comprehensive procurement and device specifications.

Classifications:

Two general classifications of sensors are considered in this specification, those that are self-powered such as passive magnetic sensors and those that require an external source of power to operate such as optical sensors. This specification addresses the self-powered and externally powered sensors separately because of the significant differences in their interface requirements. While these two sensors types have very different outputs and are considered separately in this specification, a common electronic interface could be designed to accommodate both sensor types.

Specification Terminology:

The terms "shall" and "should" within this specification observe the following rules:

a. The word "shall" expresses a mandatory requirement of the Specification.

b. The word "should" expresses a recommendation or advice on implementing the specification or actions expected of users of the system.