Downloaded from https://www.everyspec.com ADS-79D-HDBK A.5.5 Maximizing FLM benefits. Regime recognition provides the tools necessary to continuously improve aircraft design, maintenance, and safety based on actual usage. Also, the potential exists for enhanced pilot training, improved understanding of regime damage variability, and tailored risk management. The FLM Management Plan should include feedback of results to the user. Analysis of FLM data from a fatigue life management point of view will include the identification of significantly damaging usage and load environments.
For systems capable of monitoring the damage severity of a regime (example loads or severity monitoring) the parameters correlating with the degree of damage will be identified. This will allow the preparation of guidance on how to perform maneuvers and missions that are less structurally damaging. Feedback to unit commanders will maximize mission reliability and allow them to better manage their logistic requirements associated with performing each type of mission. The potential exists to extend component lives and to minimize inspection requirements by reducing the severity of the usage environment of Army aircraft systems.
A.6 RELIABILITY GUIDANCE The incorporation of a FLM management plan in Army aircraft systems should not create a system hazard as defined by the Program Executive Officer (PEO), Aviation System Safety Risk Management Process IAW MIL-STD-882. Acceptable methods of substantiating this guidance for manned aircraft systems are as follows: a. Substantiate that the frequency of the system hazard is less than the threshold of the risk matrix (i.e., probability of occurrence is less than 0.01 per 100,000 flight hours). This is a cumulative frequency of all components managed by the FLM system. Incremental incorporation should require allocation of risk. b.
Substantiate that the incorporation of FLM has not increased the aircraft system level risk. c. Substantiate that a threshold component reliability of 0.999999 (six nines) is achieved. This means that the probability of failure for components managed by the FLM system is less than 1 out of 1,000,000 components. A.6.1 Reliability analysis. The FLM objective is to retire structural components based on actual usage in order to reduce operation and support costs, and hence, to improve readiness. FLM will provide necessary usage and loads data for continued airworthiness support.
The FLM structural monitoring system provides potential service life benefit and meets the reliability requirement identified in this appendix. The following sections present examples on how reliability can be evaluated when implementing FLM for potential service benefits. The reliability analysis is a method for determining the probability of non-failure based on statistical evaluation of all critical parameters which include fatigue strength, flight loads, and usage spectrum. Fatigue reliability analysis can be predicted using analytical probabilistic models or Monte Carlo simulations.
A.6.2 Evaluation of reliability when usages are monitored and fatigue strength and flight loads are statistically evaluated (individual component fatigue damage assessment based on regime recognition) FLM usage monitoring tracks aircraft maneuvers and accumulates component fatigue damage. Component is removed when the tracked component reaches the minimum threshold of required reliability defined in this appendix. The reliability analysis is based on statistical evaluation of fatigue strength and flight load distributions when the usages of aircraft are monitored. The fatigue strength and flight load may be modeled as normal, log normal, Weibull, or other appropriate distributions.
Experimental data from fatigue characterization and component qualification bench test 39