This paper is focused on the problem of analyzing field data for truck crane which is designed to be installed to a commercial truck mainly to load/unload and transport various heavy loads. The failure data of the truck crane within the warranty period was collected from A/S center. Maximum likelihood and least squares estimators for the parameters of lifetime distribution are obtained and predict the lifetime of the three truck crane models. † To whom correspondence should be addressed. Corresponding Author: sixsigma@cnu.ac.krⓒ2014 The Korean Institute of Plant Engineering The lifetime of three truck crane models follow the Weibull distribution. Mean lifetimes of small, medium, and large size truck cranes were 6544.2 days, 201.5 days, and 239.8 days, respectively. The lifetime for small size truck crane is larger than medium and large size truck cranes. In order to improve the lifetime of truck crane, we propose that the warranty period for small size truck crane change from six month to one year. Also, the main fault components for medium and large size truck cranes can be improved.