Abstract: The failure and maintenance data character of passenger aircraft subsystem are discussed, as well as their distribution, according to engineering background, the availability assessment methods are studied with various lifetime and repair-time distribution, the point estimates and classical confidence limits for aircraft subsystem availability are given. The airplane is divided into 19 subsystems according to ATA chapters, and the batch-type operation process of aircraft subsystems are converted to be continuous operation process, on the basis of airplane operation and maintenance planning analysis. Point estimates and classical confidence intervals for availability are obtained through constructing pivotal statistic in term of exponential-exponential distributed subsystem, exponential-Gamma distributed subsystem, Weibull-Gamma distributed subsystem, and Gamma-Gamma distributed subsystem. System availability point estimate is given according to series system availability model. An engineering application is carried out to evaluate aircraft subsystem availability using airlines reliability report and maintenance records. This achievement provides technology support for conducting reliability-centered passenger aircraft healthy operation and management.

Key words: passenger aircraft;availability;Weibull distribution;Gamma distribution;service factor;confidence limits