Cycle
A cycle is one take-off and landing, and for many components it matters more than flight hours. Landing gear, pressurised fuselage structures, engine discs and brakes are life-limited in cycles because the stress of pressurisation, landing loads and engine spool-up occurs once per flight regardless of length. An aircraft flown on many short hops accumulates cycles quickly: 4,000 hours and 4,000 cycles points to a hard-worked short-haul life, while 4,000 hours and 1,500 cycles suggests long sectors and gentler use. Buyers and appraisers look at the hours-to-cycles ratio, and some inspections and engine programme charges are billed per cycle rather than per hour.