Downloaded from https://www.everyspec.com ADS-79D-HDBK Loads estimation. Equipment, techniques, or procedures to estimate the loads (forces or moments) experienced by an aircraft component during operational flight. Non-destructive inspection (NDI). Methods used to check the soundness of a structural element or component without impairing or destroying the serviceability of the structural element or component. Methods include visual, magnetic particle, liquid penetrant, eddy current, ultrasonic, radiographic, etc. Integrated NDI.
Methods that may be integrated into the design of a structural element or component which are used to check the soundness of the structural element or component without impairing or destroying the serviceability of the structural element or component. C.4 GENERAL GUIDANCE C.4.1 Aircraft mission performance impact . SHM and LME systems have the potential to enhance aircraft availability and should be incorporated into CBM Management Plans as soon as practical. However, aircraft availability should never be allowed to depend on operability of the SHM or LME system.
Alternate means of monitoring structural health, such as traditional NDI techniques with appropriate inspection intervals, maintenance schedules, and component retirement intervals, should be available for use in cases where the SHM system experiences a loss of function. Plans for SHM/LME system development and fielding should incorporate appropriate logistics support with provisions for diagnostics, component replacement, and repair. C . 4.2 Airworthiness qualification guidance . SHM and LME systems should be fully qualified in accordance with the aircraft system specification, including operation in specified environmental conditions.
In accordance with guidance contained in ADS-51-HDBK, qualification requirements should be documented in an Airworthiness Qualification Plan (AQP) and an Airworthiness Qualification Specification (AQS). C.5 DETAIL GUIDANCE C.5.1 Monitoring system. The SHM /LME system includes, as a package; sensor elements, processing and communication chips, and a power supply. The SHM/LME system must be designed to be both reliable and durable. In addition, SHM/LME component installations should not expose aircraft components to foreign object debris hazards. The design life of the system should match the design service life of the structure being monitored.
Likewise, the design environment and requirements for the SHM/LME system must be compatible with the structure. Qualification of the system for environmental and electromagnetic compatibility will be performed using the latest versions of MIL-STD-810 and MIL-STD-461 as standards, respectively. The ability of the system to identify the health of the structure and its ability to account for the variability of the ―as manufactured‖ system must be validated. Sensor selection will be based on the structure being monitored, its potential failure modes, and the data required to establish structural health.
Identification of sensor requirements may require detailed evaluation of the structure and review of its service history in order to identify critical failure modes and potential hot spots. A special application exists in cases where the rate of structural deterioration is known to increase under certain aircraft regimes or Ground Air Ground (GAG) conditions. For this application, counter and timers will provide useful data in establishing structural health. A second special application is the use of thermal sensors to monitor the health of structural joints such as the lead lag joint of a main rotor system. 63