The document discusses methods for extending maintenance check intervals for aircraft to increase availability and reduce costs. It proposes using reliability data from aircraft systems to determine if check intervals can be safely increased through analytical approaches like Weibull analysis. A case study models extending a check C interval from 1600 to 2000 flight hours for a hydraulic system. Statistical tests of reliability parameters from the system's data over several years would need to support the interval extension without adversely affecting safety.