This packet contains learning modules for a self-paced course in aircraft environmental systems mechanics that was developed for the Air Force. Each learning module consists of some or all of the following: objectives, instructions, equipment, procedures, information sheets, handouts, self-tests with answers, review section, tests, and response sheets. Topics covered in the learning modules are the following: maintenance tools, glossary, mathematics, aircraft familiarization, safety, physics, electron theory, magnetism, circuits, wiring diagrams, control and protective devices, test equipment, Kirchhoff's current law, series circuit troubleshooting, parallel circuit troubleshooting, Kirchhoff's voltage law, use of general purpose connectors, bonding, shielding, grounding, wiring maintenance, electrical hardware, aircraft air conditioning system moisture separator, maintenance of bleed air distribution ducting, cleaning agents and lubricants, controlling corrosion, air turbine motors, turbine refrigeration devices, windshield clearing system, air control valves, bench check air control units, controls of MB-3 leakage tester, airflow control and shutoff valve, bench check airflow regulator, anti-gravity system, anti-gravity suit valve, canopy seal system, pressurization principles, pressurization systems, oxygen systems, and refrigeration systems. A plan of instruction is included in the packet. (KC)