This case study explores actions of an account manager of an important maintenance agreement and a field service engineer, both newly assigned to resolve reliability issues with a set of gas turbines and a deteriorated relationship with their client. The case walks the reader through a logical and practical methodology from collection of data to proposing corrective actions in engineering and account management. The case study provides discussions on gas turbine combustion technology, combustion air emissions, commissioning, and performance degradation as background for the exercise. A reading assignment is included for understanding. Answers to exercises are provided to check comprehension. The authors propose using this case study in university study, or in industry as an individual or group assignment.