Biannual Piston And Turbine Maintenance Classes Enstrom Helicopter piston and turbine maintenance classes to equip mechanics and pilots with expert training for maintaining Enstrom helicopters have been set for summer and early fall. Classes are held at the Enstrom Factory in Menominee, Mich., for five days per course, Monday through Friday. Each class begins at 8:00 a.m. and ends at 4:00 p.m. Piston classes will be June 8-12 and September 21-25. Turbine classes will be June 15-19 and September 28-October 2. Attendees will learn the nuances of how an Enstrom helicopter operates. Instructors will walk them through inspection procedures, routine maintenance, overhaul, airframe and rotor system troubleshooting, main rotor tracking, and tail rotor balance procedures. Instructors will provide hands-on display models for participants to practice what they learn.