Downloaded from https://www.everyspec.com ADS-79D-HDBK G.7.3 Life Usage Monitoring. A complete usage monitoring system contains the following functions: 39 a. Data recording – acquisition of the necessary data for calculation of the component usage values (see Section G.7.1) b. Damage calculation – calculating the life used by each component or critical area c. Life management – organizing the life usage information to support decisions on aircraft deployment, component retirement, engine removals, and engine and spares management The physical implementation of an engine monitoring system is usually accomplished with several basic elements: a.
The airborne system hardware and software (hardware includes any additional sensors that are not part of the engine control system) b. Equipment for data transfer to the ground station c. Ground station hardware and software Usage monitoring systems rely heavily on counting the cycles and the magnitudes of the stress variations incurred through changes in the engine‘s operating conditions. Therefore, the EMS/EHMS should automatically capture and record, on an engine-by-engine basis, steady state and transient operating data and events indicative of structural life usage. Guidance for monitoring the primary parameters of a usage monitoring system is as follows: G.7.3.1 Operating Hours.
Engine operating hours should be recorded in a manner consistent with the OEM design specification and definition used to acquire and test the engine. Typically, operating hours begin with the engine at stabilized conditions immediately after engine start and end when the engine RPM reaches a defined value at shutdown. Operating time should be recorded to the nearest whole minute except where otherwise defined. G.7.3.2 Start/shut Down Cycles. Start and shutdown should be recorded consistent with the specification and design definition for the engine and recorded to the nearest whole minute unless otherwise defined. G.7.3.3 Operating Speed/Duration.
Engine operating speed should be monitored and recorded at a frequency of at least 1Hz during the period of operation (between start and shut down) as defined by the engine design specification. G.7.3.4 ITT / PTIT / EGT. ITT, PTIT, and EGT are typical parameters collected to monitor the temperature which is experienced by the turbine blades. These parameters are normally associated with turbine blade life calculations. These temperatures should be measured at an update rate of at least 1Hz during operation. 39 RTO TR 28, ―Recommended Practices for Monitoring Gas Turbine Engine Life Consumption‖, North Atlantic Treaty Organization, Research and Technology Organization, April 2000, pg. 7-3.
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