Modern start systems for large gas turbine engines typically employ a pneumatic starter. The reliability of the pneumatic starter has a direct impact on flight dispatch reliability. This is due to the nature of its task and the fact that it is typically called to perform this task immediately prior to departure. The ever increasing performance demands placed on the starter require that the starter design be continually refined in order to improve overall start system performance and increase flight dispatch reliability.After analyzing starter malfunctions, a number of design improvements were defined. Prior to production incorporation, limited quantities of hardware of improved design were sent to specific airlines for evaluation in “real world” applications. This affords an evaluation of the performance of these design improvements and a measure of the increase in reliability which can be expected.