Psychological approaches to the troubleshooting of complex military equipments are designed to improve the selection, motivation, and training of technicians. Methods for enhancing the understanding of the physical relations in equipment, the hierarchical analysis and practice of sub-skills, and the general logic of searching behavior are aspects considered. The "aiding" approach provides technicians with an information base in special booklets, diagrams, computer programs, and directed sequences. The "maintainability" approach concentrates on designing equipments for troubleshooting ease. When these approaches are applied to troubleshooting problems, the great majority can be solved. For troubleshooting equipments already in service, proceduralized aiding is probably the best for immediate solutions, especially for many one term military technicians. Aids must be designed from a behavioral standpoint and be specially prepared, tested, and debugged. The most effective aids, however, will not find all troubles, and people with relatively deep skill levels will always be required. To provide such people, research is needed in the visualization and memory of complex physical events, the learning of long branching sequences, individual differences in search behavior, and enhancement of human reasoning by small computerized devices. (Author/RAA)