Downloaded from https://www.everyspec.com ADS-79D-HDBK G.7.1.4 Data Management. Engine and APU data should be carefully managed by onboard and ground systems to ensure integrity throughout its lifecycle from collection to destruction. Detailed guidance specific to proper data handling procedures is provided in Appendix L –Data Integrity. As described in Appendix L, the degree to which data should be managed to ensure integrity is ultimately determined by the criticality of the maintenance decision derived from the data.
As a result, engine and APU maintenance decisions which could result in catastrophic, hazardous/severe, or major safety issues carry a higher burden for managing the associated data against corruption / loss. The Engine and APU CBM design should also specify procedures for recovery in the event of data loss or corruption. Again, criticality should serve as guidance for the measures taken to re-establish engine and APU maintenance in the event that data is compromised. Given the cost and effort to acquire engine and APU data, the design should anticipate long-term archival of captured data.
This broader approach to retaining maintenance data will allow for later data mining to uncover long-term trends in engine and APU reliability, availability, and performance that can be used for future improvements to CBM algorithms. G.7.2 Exceedance Recording. Any significant exceedances should be recorded when each event occurs and flagged to the ground crew. Exceedances may be used to trigger a usage assessment. G.7.2.1 Hot Starts. In conformance with the engine design definition for out of limit conditions on start, the duration and maximum temperature reached during an improper (‗hot‘) start should be recorded to the nearest second. G.7.2.2 Over Torque.
In conformance with the engine design definition, conditions which represent out of limit conditions for torque applied by the engine (‗over-torque‘) should be recorded to the nearest second and should include the maximum value sensed by the torque sensor during the period of exceedance. G.7.2.3 Overspeed. In conformance with the engine design definition, conditions which represent out of limit conditions for the compressor and power turbine speeds (typically known as Ng or Np) should be recorded to the nearest second and should include the maximum value sensed by the sensor during the period of exceedance. G.7.2.4 Over-temperature.
In conformance with the engine design definition, conditions which represent out of limit readings for temperature as measured by the installed temperature sensors should be recorded to the nearest second and should include the temperature reached at each second during the period of exceedance. G.7.2.5 Vibration. In conformance with the engine design definition, conditions which represent out of limit readings for vibration should be recorded to the nearest second and should include the value sensed by the accelerometer during the period of exceedance.
EMS/EHMS should monitor the engine vibration and dynamic response at all engine speeds and powers including steady state and transient operation throughout the environmental conditions and operating envelope of the engine. The monitoring system should indicate / prognosticate trends towards exceedance of engine vibration limits at each sensor location for the compressor, turbine, and gearbox sections. The monitoring system should automatically correlate vibrations with component degradation / damage. The monitoring system should detect unusual vibration changes while distinguishing between airframe, drivetrain, and engine induced vibrations to prevent false indications. 127